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A  TEXT  BOOK  OF  PHYSIOLOGY. 


in,iiinnrU!\TfO(.ocv 


A    TEXT    BOOK 


OF 


PHYSIOLOGY 


BY 


JOHN  GEAY  M'KENDEICK,  M.D.,  LL.D.,  F.E.S. 

PROFESSOR   OF   THE   INSTITUTES   OF  MEDICINE   IN  THE   UNIVERSITY  OF   GLASGOW, 
FELLOW   OF   THE   ROYAL   COLLEGE   OF   PHYSICIANS  OF   EDINBURGH. 


INCLUDING 

HISTOLOGY  BY  PHILIPP  STOHE,  M.D., 

OF   THE   UNIVERSITY   OF  WiJRTZBURG. 


IN  TWO  VOLUMES. 

VOL.    I.— OENEEAL    PHYSIOLOGY. 


NEW     YOEK: 
MACMILLAN     AND     CO. 

1888. 


I/.  I 


^ 


B'C      D  Eh       F  G        ' 


MoLc  Muivn,  deL  acL  Nax, 


Ifanfwrb  UJJv. 


GENERAL  PHYSIOLOGY: 


INCLUDING 


THE  CHEMISTRY  AND  HISTOLOGY  OF  THE  TISSUES 
AND  THE  PHYSIOLOGY  OF  MUSCLE. 


BY 


JOHN  GEAY  M'KENDPtICK,  M.D.,  LL.D.,  F.R.S., 

PROFESSOR   OF   THE   INSTITUTES   OF  MEDICINE   IN   TUE   UNIVERSITY  OF   GLASGOW, 
FELLOW   OF   THE   ROYAL  COLLEGE   OF   PHYSICIANS   OF    EDINBURGH. 


NEW     YORK: 
MACMILLAN     AND     CO. 

1888. 


V.  t 


PRINTED   AT  THE   U^fIVERS^TY   PRESS,  QLASOOW, 
BV   ROBERT   MACLEHOSE. 


VIRO  •    ADMIRABILI 

ACERRIMO  .   IN  .    NATVRA  •    INVESTIGANDA 

IN  .   INTERPRETANDA  •    SAGACISSIMO 

lOANNI •  BVRDON  ■  SANDERSON 

QVI  .    LARGIS  •    INGENII  ■    LVMINIBVS 

QVODCVNQVE  •    ATTIGIT  ■    ILLVSTRAVIT 

SANO  .    IDEM  .    IVDICIO  •    ATQVE  ■    AEQVO 

SOLIDA  •    SEMPER  •   VANIS  •    PRAETVLIT  ■    VTILIBVS  •    HONESTA 

ATQVE  .    OMNIA  .    POSTHABVIT  •    VERITATI 

HOC  •    MVNVS  •    QVALECVNQVE 

D.  D. 
lOANNES  •   G  •    M'KENDRICK 


PREFACE, 


Although  this  work  has  been  modelled  to  some  extent  on  my  "  Out- 
lines of  Physiology,"  now  out  of  print,  it  is  essentially  a  new  book,  and 
as  it  aims  at  giving  a  more  detailed  account  of  the  subject,  the  title  of 
"Outlines  of  Physiology"  has  been  abandoned  for  that  of  a  "Text 
Book  of  Physiology."  I  have  not  endeavoured  to  give  anything  like  an 
encyclopaedic  account  of  the  modern  researches  that  have  built  up  the 
physiological  science  of  the  present  time,  but  rather  to  weave  into  a  con- 
secutive narrative  the  main  facts  and  principles  of  physiology,  as  these 
present  themselves  to  my  mind,  after  nearly  eighteen  years  of  experi- 
ence as  a  teacher  of  the  science.  Probably  no  science  is  advancing  with 
greater  rapidity,  if  one  may  form  an  opinion  from  the  large  number  of 
original  papers  that  are  announced,  month  by  month,  and  from  the  large 
number  of  investigators  in  the  physiological  laboratories  of  the  Con- 
tinent, of  America,  and  of  our  own  country.  Thus  it  is  year  by  year 
becoming  more  difficult  for  a  teacher  to  keep  abreast  of  the  wave  of 
progress,  and  still  more  difficult  to  assimilate  the  new  facts  and  to 
incorporate  them  with  his  previous  knowledge.  Each  teacher  will  also 
view  the  subject  more  especially  according  to  his  predilections  for  the 
morphological,  the  chemical,  or  the  physical  side  of  the  science,  and 
it  is  not  easy  in  the  preparation  of  such  a  work  as  this  to  be  im- 
partial and  to  present  the  science  in  all  its  completeness  to  the 
reader. 

An  explanation  may  be  expected  as  to  my  object  in  introducing 
another  large  work  on  physiology  when  in  recent  years  several  excellent 
and  voluminous  treatises  have  issued  from  the  press  and  have  met  with 


X  PREFACE. 

great  acceptance.  My  chief  reason  is  to  have  it  in  my  power  to  place 
in  the  hands  of  my  students  a  text  book  appropriate  to  the  course  of 
instruction  in  physiology,  which  it  is  my  duty  to  give  annually  in  the 
University  of  Glasgow.  The  present  work  contains  most  of  the 
theoretical  teaching  given  to  the  student,  and  I  hope  that  with  it  in  his 
hands,  it  will  be  possible  for  me  to  do  more  and  more  in  the  way  of 
demonstration  and  of  practical  instruction.  At  the  same  time,  I  am  not 
without  the  hope  that  the  nature  of  the  liook  may  be  such  as  to  com- 
mend it  to  a  wider  circle  of  readers,  more  especially  to  members  of  the 
medical  profession  who  desire  to  become  acquainted  not  only  with  the 
facts  but  also  with  the  methods  of  physiology. 

The  general  plan  of  the  book  is  to  give  an  account  both  of  methods 
and  of  results,  and  to  introduce  illustrations  as  far  as  possible  |from  the 
best  sources.  No  expense  has  been  spared  to  obtain  good  illustrations, 
not  merely  diagrams,  but  illustrations  that  will  give  the  reader  a  fair 
idea  of  the  appearance  of  the  thing  represented.  The  reader  is  recom- 
mended carefully  to  peruse  the  descriptions  of  the  various  figures, 
as,  in  these,  information  is  often  given  which  is  not  contained  in  the 
text. 

The  work  is  primarily  divided  into  two  parts.  First,  that  relating  to 
the  general  physiology  of  the  tissues,  which  forms  the  subject  of  the 
first  volume ;  and,  second,  that  relating  to  the  special  physiology  of 
organs,  to  be  discussed  in  the  second  volume.  This  arrangement  is 
simple  and  comprehensive.  After  an  introductory  section  dealing  with 
general  notions  as  to  living  matter,  more  especially  with  reference  to 
the  great  doctrines  regarding  energy,  which  form  the  basis  of  modern 
science,  I  proceed  to  discuss  the  nature  and  properties  of  the  chemical 
.substances  found  in  the  body  and  the  nature  of  the  chemical  reactions 
with  which  the  phenomena  of  life  are  associated.  In  this  section  I  have 
introduced  a  chapter  explaining  to  the  physiological  student  the  views 
he  should  hold  as  to  the  true  value  of  chemical  formulae.  This  chapter, 
in  the  preparation  of  Avliich  I  received  valuable  assistance  from  Professor 
W.  Dittmar,  F.E..S.,  I  introduced  after  much  consideration,  and  because 
I  know  that  in  the  minds  of  most  students  there  is  not  a  little  confusion 
regarding  this  matter.  No  doubt  such  a  chapter  would  be  more 
appropriate  in  a  strictly  chemical  work,  but  my  experience  as  a  teacher 


PREFACE.  xi 

assures  me  that  it  will  not  be  without  its  value  even  in  a  physiological 
text  book,  did  it  serve  no  other  purpose  than  to  shoAV  how  little  we  yet 
know  of  the  molecular  structure  of  organic  chemical  substances.  In 
the  preparation  of  this  section  I  derived  much  assistance  from  Dr. 
Arthur  G-amgee's  Physiological  Chemistry  and  from  Beaunis'  Physiologie 
Bumaine. 

I  venture  to  direct  the  attention  of  the  reader  to  the  chapter  on  pig- 
ments in  which  these  interesting  substances  are  more  fully  discussed 
than  has  yet  been  attempted  in  any  text  book  of  physiology.  The 
writings  of  Dr.  C.  A.  MacMunn  of  Wolverhampton  have  largely  assisted 
me  in  writing  this  chapter.  Dr.  MacMunn,  as  is  well  known,  has  made 
this  subject  his  own  special  field  of  research,  and  from  his  stores  of 
knowledge  he  gave  me  the  valuable  measurements  of  wave-lengths. 
He  also  kindly  prepared  the  chart  of  spectra  which  forms  the  frontis- 
piece of  this  volume,  and  he  added  further  to  my  indebtedness  by  read- 
ing the  proof  sheets  of  the  chapter  on  pigments  and  by  furnishing  me 
with,  many  valuable  suggestions.  I  consider  myself  fortunate  in  having 
secured  Dr.  MacMunn's  co-operation,  and  I  offer  him  my  most  cordial 
thanks. 

The  next  section  deals  with  the  physiology  of  the  tissues.  Here  I 
was  met  by  a  great  difiiculty.  In  my  previous  work  scarcely  any 
description  of  the  microscopical  structure  of  the  tissues  or  organs,  or 
Avhat  is  termed  histology,  was  introduced,  and  the  omission  was 
regarded  by  critics  as  diminishing  the  value  of  the  book.  My  own 
feeling  was  in  favour  of  omitting  the  discussion  of  histology  from  a 
physiological  text  book,  but  after  consulting  several  physiologists,  in 
whose  judgment  I  place  great  confidence,  and  after  taking  into  account 
the  wishes  of  my  students,  I  found  that  the  balance  of  opinion  was  in 
favour  of  introducing  histology.  At  the  same  time,  I  am  bound  to  admit 
that  several  physiologists  gave  good  reasons  for  omitting  histology. 
Having  resolved  to  introduce  this  aspect  of  physiological  science,  the 
next  difiiculty  was  whether  I  was  prepared  to  face  the  trouble  and  cost 
of  preparing  a  new  set  of  histological  woodcuts.  After  some  consider- 
ation, I  solved  the  problem  by  purchasing  from  Mr.  Gustav  Fischer,  the 
well-known  publisher  in  Jena,  a  set  of  electrotypes  of  the  woodcuts  in 
Professor  Philipp  Stohr's  Lehrbuch  der  Histologie,  published  last  year,  and 
also  the  right  of  translating  the  work,  and  of  ineori:)orating  it  with  my 


3fii  PREFACE. 

book.  This  arrangement  was  effected  Avith  the  cordial  consent  of  the 
author,  Dr.  Stohr,  whose  name  I  therefore  place  on  the  title  page.  Dr. 
Stohr's  work  commended  itself  to  me  on  account  of  the  excellence  of  its 
descriptions,  the  fidelity  of  its  illustrations, — which  are  not  diagrams  but 
drawings  of  real  preparations,  — and  the  value  of  its  practical  directions 
I  have  therefore  made  free  iise  of  it,  introducing  special  descriptions  and 
illustrations,  where  these  seemed  to  be  needful,  and  I  have  done  this  the 
more  readily  as  the  directions  given  l)y  Dr.  Stcihr  are  substantially  those 
followed  from  year  to  year  in  the  practical  classes  held  during  the 
summer  session  in  the  University  of  Glasgow.  Having  Dr.  Stohr's 
work  at  my  command  has  also  led  me  to  introduce  more  in  the  way  of 
practical  directions  as  to  histological  methods  than  I  might  otherwise 
have  done,  so  that  the  present  volume  will  be  a  guide  to  the  student 
during  the  practical  work  of  summer,  and  at  the  same  time  serve  as  a 
systematic  text  book.  One  unique  feature  of  Dr.  Stohr's  work  is  that 
he  gives  an  account  of  the  method  by  Avhich  each  preparation  figured 
was  prepared.  These  descriptions  of  methods  I  have  relegated  to  an 
appendix  and  numbered  consecutively  so  as  to  admit  of  ready 
reference. 

Before  taking  up  the  physiology  of  the  tissues,  I  have  discussed  their 
origin  in  the  light  of  recent  investigations  regarding  the  phenomena  of 
fecundation  and  the  minute  structure  of  cells  and  of  nuclei.  This  is  a 
novel  arrangement,  so  far  as  recent  systematic  works  are  concerned,  but 
it  has  commended  itself  to  me  as  one  leading  to  a  philosophical  view  of 
the  whole  subject.  The  cpestions  as  to  the  origin  of  the  tissues  and  the 
mysterious  Avay  by  which  they  are  impressed  with  hereditary  characters 
are  of  profound  importance  and  have  a  bearing  not  only  on  physiological 
but  on  pathological  theories.  The  portion  dealing  A^ath  the  theories  of 
heredity  has  been  read  by  Professor  E.  Eay  Lankester,  F.R.S.,  who,  Avhile 
not  agreeing  with  me  in  m}'  general  conclusion,  has  giA^en  me  A^aluable 
suggestions  and  criticisms.  The  Avhole  of  this  section  has  also  been  read 
by  Mr.  J.  H.  Fiillarton,  M.A.,  B.Sc. 

Section  III.  deals  Avith  the  contractile  tissues,  the  studj'  of  Avhich 
requires  physical  appliances.  I  still  hold  that  AAdthout  burdening  a 
student  by  requiring  of  him  a  knoAA'ledge  of  complicated  apparatus,  it 
is  possible  to  giA^e  him,  shortly,  such  information  regarding  methods  as 
AAdll  enable  him  to  take  an  intelligent  view  of  results.    Instead,  hoAvever, 


PREFACE.  xiii 

of  introducing  a  description  of  apparatus  in  the  parts  describing  results, 
I  have  discussed  apparatus  and  methods  as  far  as  possible  in  separate 
chapters,  so  that  the  reader  may  pass  over  these  if  he  chooses.     The 
importance  of  the  uses  of  electricity  in  practical  medicine  and  surgery 
appears  to  me  to  justify  the  account  given  of  electrical  apparatus,  for 
assistance  in  the  preparation  of  which  I  am  indebted  to  Mr.  Thomas 
Gray,  of  the  Physical  Laboratory  of  this  University,  and  an  accomplished 
electrician ;  and  the  immense  value  of  the  graphic  method  in  all  sciences 
dealing  with  movements  also  warranted  me  in  giving  a  brief  account  of 
its  chief  instruments.     As  to  the  introduction  of  physical  questions  into 
a  text  book  of  physiology,  a  good  deal  can  be  said  on  both  sides.     No 
doubt  if  students  of  medicine  and  practitioners  read  good  text  books  on 
general  physics,  or  the  excellent  works  on  physiological  physics  that 
have  ajDpeared  in  recent  years,  there  would  be  little  or  no  necessity  for 
introducing  these  matters  into  a  text  book  of  phj^siology,  except  in  so  far 
as  all  physiological  questions  ultimately  resolve  themselves  into  physical 
problems.     But  the  fact  is  that  the  teacher  has  usually  to  deal  with 
students  who  know  little  or  nothing  of  physics.     The  examination  in 
mechanics  required  for  the  registration  of  a  medical  student  is  of  no  use, 
but  is  just  sufficient  to  worry  him  and  exhaust  his  energies  without  con- 
ferring any  real  benefit  in  the  shape  of  a  knowledge  of  the  principles  of 
physical  science.    Had  he  a  course  of  instruction  in  general  physics  before 
beginning  the  study  of  medicine,  matters  would  be  on  a  different  footing, 
but  that  is  not  at  present  available.    Consequently  the  teacher  need  not 
lecture  on  the  appearance  of  a  muscle  as  seen  with  polarized  light  without, 
in  the  first  instance,  stating  the  more  elementary  facts  regarding  polarized 
light,  and  without  explaining  the  construction  of  a  polarizing  apparatus. 
Again,  before  beginning  the  discussion  of  muscle  in  which  the  physio- 
logical teacher  must  make  use  of  electricity,  he  is  obliged  to  give  some 
explanation  of  the  nature  of  voltaic  cells,  of  induction  coils,  and  of  the 
general  facts  regarding  resistance,  and  of  the  detection  and  measurement 
of  currents.     For  these  reasons  I  have  introduced  certain  details  as  to 
physics  just  as  I  am  obliged  to  introduce  them  in  my  lectures.     At  the 
same  time,  I  admit  that  this  is  so  far  a  provisional  arrangement,  and  if 
the  time  arrives  when  the  student,  beginning  the  study  of  physiology, 
has  already  been  well  grounded  in  even  elementary  physics,  it  may  be 
abandoned.     I  have  in  the  meantime  chosen  the  mode  of  teaching 


xiv  PREFACE. 

which  experience  has  shown  mc  to  lie  the  most  useful  under  the 
circumstances. 

The  chapter  on  the  electrical  fishes  is  longer  than  might  be  exi)ectcd 
in  a  general  treatise  on  jihysiology,  but  I  have  thought  it  right  to  enter 
into  details  regarding  these  remarkable  animals,  as  their  physiology  has 
an  important  bearing  on  questions  as  to  the  functions  of  nerve  and 
muscle.  I  am  much  indebted  to  Professor  Burdon-Sanderson  for  aiding 
me  with  a  description  and  with  drawings  of  the  electric  organ  of  the 
skate,  in  the  investigation  of  which  he  and  Mr.  Francis  Gotch,  M.A., 
have  been  recently  engaged  and  the  results  of  Avhich  have  not  been 
published.  I  have  also  to  thank  Mr.  Gotch  for  looking  over  the  proof 
sheets  of  this  chapter  and  for  valuable  suggestions. 

In  the  preparation  of  the  entire  volume,  I  have  gratefully  to  acknow- 
ledge the  valuable  services  of  my  assistants.  Dr.  J.  M'Gregor-Robertson, 
M. A.,  and  of  Dr.  William  Snodgrass,  M.A.  Dr.  Snodgrass  has  read  all 
the  proof  sheets  twice  over,  and  Dr.  M'Gregot'-Robertson  has  read  the 
final  revise.  Both  have  given  me  great  help  and  excellent  suggestions. 
Mr.  J.  T.  Bottomley,  M.A.,  F.E.S.,  and  Mr.  Magnus  Maclean,  M.A.,  have 
also  aided  me  in  the  discussion  of  various  physical  questions. 

I  have  also  to  thank  Professor  Rutherford,  F.R.S.,  Professor  Marey, 
the  Cambridge  Scientific  Instrument  Company,  Messrs.  Churchill, 
Blackie  &  Son,  A.  &  C.  Black,  Cassell  &  Co.,  Collins  <fc  Sons, 
Yieweg  &  Son  of  Brunswick,  Fischer  of  Jena,  Hahn  of  Hanover,  Carl 
Ricker  of  St.  Petersburg,  Vogel  of  Leipsig,  and  Masson  of  Paris,  who 
have  favoured  me  -with  electrotypes  of  illustrations  for  this  work.  The 
soiu:'ces  of  all  the  illustrations  are  given  in  the  list  of  woodcuts. 

I  am  indebted  for  the  index  to  my  pupil,  Mr.  Alexander  Far- 
quharson. 

The  second  volume  is  ready  for  the  press  and  will  be  published  with- 
out delay. 

With  these  introductory  remarks,  I  submit  the  work  to  the  reader, 
in  the  hope  that  he  may  find  it  a  guide  to  the  study  of  physiology  and 
possibly  a  stimulus  to  further  research. 

JOHN  G.  M'KENDRICK. 

University  of  Glasgow, 
May,  188S. 


CONTENTS. 


SECTION  I.— GENERAL  INTRODUCTION. 

PAGE 

Chap.  I. — Nature  and  Objects  of  Physiology,  .  .  .  .  1 

Chap.  II.  — Matter  and  Energy,  ......  4 

Matter ;  Measurements;  Eneryy. 
Chap.  III. — General  Principles  of  Biology,     .  .  .  .  .1.3 

Physical  Structure  ;  Chemical  Composition  ;  Organic  Form  and  Mode  of  . 
Growth;     Dynamical    Characters;    Evolutional   History  of   Living 
Beings;  Theories  of  Life. 

SECTION  II.— THE  CHEMISTRY  OF  THE  BODY. 

Chap.  I. — The  Inorganic  Constituents,  .....         34 

Water  ;  Mineral  Matters, 
Chap.  II. — The  Chemical  Constitution  of  the  Organic  Constituents,  .         43 

Classification  of  Organic  Compounds. 
Chap.  III.— The  Proteids  or  Albuminoids,     .  .  .  .  .57 

Chemical    Characters ;    Physical    Characters ;    Polarized    Light    and 
Polariscopes  ;  Physiological  Characters. 
Chap.  IV. — The  Characters  of  the  Special  Proteids, .  .  ,  .         72 

Tr^ie  Alhumiiis  ;  Albuminous  Derivatives. 
Chap.  V. — The  Nitrogenous  Proximate  Principles  other  than  the  Proteids,         81 

Fatty  Nitroge7ious  Principles  ;  the  Amides, 
Chap.  VI.  — The  Nitrogenous  Proximate  Principles,  .  .  .89 

The  Amides,  or  Amido-Acidn. 
Chap.  VII. — The  Nitrogenous  Acids,  .....         97 

Bile  Acids. 
CH.iP.  VIII. — The  Nitrogenous  Bodies  containing  no  Oxygen,  .  .       109 

Chap.  IX.— The  Pigments,      .  .  .  .  .  .  .111 

Principles  of  Spectroscopy  ;  Pigment  of  the  Blood  and  its  Derivatives; 
Pigments  of  the  Bile  ;  Pigments  of  the  Urine  ;  Pigments  of  the  Faeces  ; 
Pigments  of  the  Tissues ;  Luteins  or  Lipochromes ;  Chromophanes ; 
Black  Pigment;  other  Animal  Pigments;  Conclusions  regarding  the 
Pigments, 


xvi  CONTENTS. 


PAGK 


Chap.  X. — The  Non-Nitrogenous  Matters,      .....       146 
The  Alcohols;    the   Fats;    the   Carbohydrates;    the    Non-Nitrogenous 
Orrfanic  Acids. 

Chap.  XL— The  Gases,  .......       168 

Chap.  XII. — The  Chemical  Keactious  in  the  Living  Organism,         .  .170 

Oxidations  ;  Reduction  ;  Decom'position ;  Synthesis ;  Fermentation. 

Chap.  XIII. — Fermentation,    .  .  .  .  .  .  .175 

The  Soluble  Ferments  ;  the  Orrjanized  Ferments  ;  Chemical  Classification 
of  Ferments  ;  Nature  of.  the  Organized  Ferments  ;  Modes  ofCultivatini/ 
Schizomycetes. 


SECTION  III.— THE  PHYSIOLOGY  OF  THE  TISSUES. 

Chap.  I. — Historical  Introduction,      .  .  .  .  .  .  .       201 

Chap.  II.— The  Origin  of  the  Tissues,  .   .  .  .  .  .214 

Spermatozoa;  Ova;  Influence  of  Spermatozoid  on  Ovum ;  Polar  Bodies  ; 
Fecundation. 

Chap.  III. — Theories  as  to  the  Physiological  Basis  of  Heredity,       .  .       234 

Chap.  IV. — Formation  of  the  Blastodermic  Layers,  ....       244 

Chap.  V. — Tlie  Microscope  and  the  Methods  of  Microscopical  Research,     .       252 

The  Microscojye ;  Accessory  Appliances;  Reagents;  Preparation  of 
Tissues  and  Organs. 

Chap.  VI. — Microtomes  and  Serial  Section  Cutting,  .  .  .  .•     278 

Chap.  VIL— Protoplasm  and  Cells,    .  .  .  .  .  .288 

Modes  of  Studying  Protoplasm;  Cells;  Size,  Nutrition,  Movements, 
Formation.,  Secretion,  Growth,  and  Evolution  of  Cells. 

Chap.  VIIL— Structure  of  the  Varieties  of  Cells  and  of  Cellular  Tissue,     .       299 
Leucocytes ;  Coloured  Blood  Cells ;  Ejnthelial  Cells  :  Connective  Tissue 
Cells  ;  Fat  Cells  ;  Aluscle  Cells  ;  Examination  of  Muscle  by  Polarized 
Light;  Nerve  Oells. 

Chap.  IX. — The  Physiological  Properties  of  Epithelium,      .  .  .       317 

Ciliary  Motion. 

Chap.  X. — The  Intercellular  Substance,  .....       322 

White  Fibrous  Tissues. 

Chap.  XL — The  Structure  of  the  Connective  Tissues,  .  .  .       324 

The  Connective  Tissues  Proper ;  Cartilage;  Chemical  Composition  of 
Cartilage  ;  Bone;  Microscopical  Structure  of  Bone  ;  Marrow  ;  Develop- 
ment of  Bone  or  Ossification  ;  Chemical  Composition  of  Bone. 

Chap.  XII. — The  Physical  and  Vital  Properties  of  the  Connective  Tissues,       343 
Specific  Weight;  Consistence;  Cohesion;  Elasticity;  Vital  Properties. 

Chap.   XIII. — Phenomena  of  Filtration   and  of  Osmosis  in  Relation  to 

Tissues,  ........       347 


CONTENTS. 


xvu 


SECTION  lY.— THE  CONTEACTILE  TISSUES. 

PAGE 

Chap.  I. — The  Special  Structure  of  Muscles  and  their  relations  to  Xerves,         356 

Motor  End- Plates. 
Chap.  II. — The  Chemical  Composition  of  Muscle,      ....       360 
Chap.  III. — Electrical  Apparatus  employed  in  the  Study  of  Muscle,  .       363 

General  Statement  and  Definitions  ;  Voltaic  Elements  ;  Induction  Coils  ; 
Accessory  Aijpliances ;  Key;  Metronomic;  Kro7iecher\s  Contact - 
Brealcer  ;  PohVs  Commutator  ;  Polarizable  Electrodes  ;  Non-Polariz- 
able  Electrodes. 

Chap.  IV.— The  Graphic  Method,       .  .  .  .  .  .381 

Chronognxphy ;   Revolving  Cylinder ;    Direct  recording  of  Movement; 
Transmissio7i  of  Movement. 
Chap.  V. — The  Physical  Properties  of  Muscle,  ....       397 

Consistence  ;  Coliesion  ;  Elasticity. 
Chap.  VI. — Muscular  Irritability,        .  .  .  .  .  .       400 

Chap.  VII. — General  Phenomena  of  Muscular  Contraction,  .  .       405 

Phases  of  a  Single  Contraction  or  Twitch  ;  Propagation  of  a  Wave  of 
Contraction. 
Chap.  VIII. — The  Genesis  of  Tetanus,  .  .  .  .  .414 

Chap.  IX. — Modes  of  Exciting  Muscular  Contraction,  .  .  .418 

Electrical  Stimuli ;   Mechanical  Stimuli ;    Thermal  Stimuli ;    Chemical 
Stinmli. 
Chap.  X.— The  Production  of  Heat  by  Muscle,  .  .  .  .421 

Chap.  XI.— The  Work  done  by  Muscle,  .  .424 

Chap.  XII.— The  Muscle  Sound,         .  .  .  .  .  .       427 

Chap.  XIII. — -The  Phenomena  of  Muscular  Fatigue,  .  .  .      428 

Chap.  XIV.— The  Nutritive  Changes  or  Metabolism  in  Muscle,  .       430 

Chap.  XV. — The  Phenomena  of  Cadaveric  Rigidity,  .  .  .       432 

Chap.  XVI.  —The  Growth  and  Atrophy  of  Muscle,   ....       433 

Chap.  XVII. — The  Properties  of  Non-Striated  Muscular  Fibre,        .  .       435 

Chap.  XVIIL— The  Electrical  Phenomena  of  Muscle,  .  .  .436 

Chap.  XIX. — Summary  of  the  Phenomena  of  a  Living  Muscle,         .  .       460 

Chap.  XX. — The  Phenomena  of  the  Electric  Fishes,  .  .  .461 

Appendix  I. — Methods  of  Histological  Eesearch,       ....  487 

Appendix  II. — Chemistry  of  Muscle,  .....  501 

Appendix  III. — Latent  Period  of  Muscle,       .....  503 

Index,   ..........  505 

Explanation  of  Plate  of  Spectra,' page  144. 


LiT^ri.^r::xs- 


Mag  €C  I'SganBitginJ  i^ecsga^ 
1.  3EImKES!s  Stslk. 

4i-   *l  rnrnr-  <*^S[DjJ!IIItSIiri- 
i    SihiSTirW; 

i.  3tnjHisii  far  li  r.-mr.  -  - 

~>T.'    i''''ri,ii   frnn:  ?".rri-Trniri-°-n. 

ZI.  CariiTTTiKg-  di  "rriTfr  TxEna. 

T^y     "DariillliESE  ir  Thttij^  Tmryt. 


M. 

Sl 

21. 

22. 

3{L 


i^boo^  JMc 


Ciirfa-jtHrr 


^teioyfeiL 


"WKomm^  laiS-rm  -Mrrnr  "WPttit— yr)  I'r 


"C::^,  _        -        .        .        - 


SL  Wffinnm, 


38. 


Yrei 


3&.  C^sQB, 


ST. 


Fr^li, 


« 

* 
17 

41 
4f 

<T 
<^* 

■'» 


1«7 


UST  OF  ILL  rSTBA  TIOFS.  xht 


40.  CiMlaEc  Acid, ^''^i'- ^^ 

-H.  Scale  i£  "Wave  Leigtlis,       ....     *'ri<:!iei<ue..u  ...        -  122 
42.  Arrangemfint  of  Spectroscope.     ...         -     Fmti   mi^tii<r:ipi   '-.•!  2£(a:- 

M'mru  ....  112 


^v^EMIflSC^^  • 


43.  HEmaTioscope, 

44.  Arrangement  of  Prisma  in  direcT;  visMB  9^t  (in 

scope, 

45.  llicro-spectroacope,      ...-•--  ^^"^ 

46.  ilicro-spectroacope  of  Sorby,        .  Br^WKOHf^  .  1  .:^ 

47.  Vie-vr  of  pan:  of  Apparauis  ^o.  4-".  Zan,  ....        -    l-» 

48.  Crystals  of  Oxy-haemogiobHU     ...        -     :a«i^fieifwam  G*cnuiee.iifSer 

JFmJbe,  11» 

I3i 


Ifl 

133 


a;.}.  Diagram  of  Spe^noK  a€  K^aq^olHi  aad  ef 

05y-hi.MaiJu«BBi, 

.30.  Diagzam  of  AbaoKp&a  «f  Li^  by  Osy-fcaoM- 

^obn, BsOa, 

.">!.  DJagtamrfAlwMKpauBef  Lj^^HirwMelilrMi,  Affict, 

.32.  WapwatwHm, JR^q^ 

-M.  H-^ciiii.                                                                     -  frey,  .  13» 

.>5.  Bilimbiii.  FreKy   .  1^* 

-■j*;.  Spectmii:  of  C"_l;. ;  /_ --r  KSJini;.  1* 

-57-  Spectrum  c:  T.       ^                                               -  iTSA*;.  1* 

.56l  Speelnimc:  :  .                                                       -  KSkau.  1-^ 

-5©.  Spectr--   ; :  J  _    :                                                      -  .ffBto.?.  IS 

«).  Pigme-:      r.                                                                -  i%8y,  ^"^ 

6L  Cholesteniu         ...                                   -  Firj,   .  -^ 

^Q.  Fat  C^b,  showing  Crystals,                                 .  Fmj.  149 

<>3.  Si)tie4«n>oliirTiiwt^  of  Ton  Flexjchl,  ....  -  -^ 

ftl.  laoEsfie. ^'Tf!'-  -^~ 

€9u  QsaOateafline^         ...  .Frs;;/^ loi> 

6&  TjiaealFanKaf  Sdmoarfeetei.  M^inhjoll  W,i2^d,'ifter  Zivf.    !■*!» 

67.  Types  of  Spate  Fonatttat  in  Srfifmmjeetes,      .  JfarsM?  ir««l,  mf^erZa^,    130 

eS.  BadHas  Antfaadsy JfawftrfT  Wkfi  ^&r  J&k*.    IM 

^.  bMnliator,  ...  ^^ 

70.  Thezm»zega]ataF, 1^ 

7L  DngnBt  diownig  liaiSa&ta3aaD&  <d  Tiews  a^  uo 

MorplwlngrafCdi, ^03 

72.  CooBeeiive    T^soe    Corpssdle    firan   S6m   of 

Tiitasi, 5Sir.  .  3QS 

7S.  Cenfironl&atejoaf  HydEspid!&^     .                 -  Cmoneti.  fOC 

74.  'SiicLa.frfmi'EgaAsewdBe£SalamaadEX.  .  Ckermy.  ±10 
7-x  GLuiu  Cells  fEomBMeafazniw  of  BalU^  .  Qamov.  39 
7d.  Cell  and.  Xncie^  €nim  btesfimal  BpMtdtuHt  of 

Maggot,          ....                 .        .  iSnua'j.  21 

77.  Diagram  <tf  Karyostenasisi,          .        .                 .  -        .  ±13 

75.  Stages  oE  KazyakinBas  is  Nwfeas  •£  CdUi  of 

Ejaiezmis  (fErttoM, SSSur,  .  33 

79.  Transverse  SectioB  of  Testiciev   .        -         -         .  SBir.  ±15 

50.  Tklqs  verse  SeeiiwKif  TbIwS  SeminSiaEi  ef  Cte, .  SSS&r,  .  ±i<* 

51.  Diagnim  of  ^p^nsaakigissie^s.  l^B&wfe  Geiietg  mfoar  £mm- 


52.  Dia-rrajn  of  SpeuBafaigeMcgs.     ....     ^tinsi  Ggdies.  m^arSa&amt  ST 


XX 


LIST  OF  ILLUSTRATIONS. 


83.  Isolated  Elements  of  Testis  of  Ox,     . 

84.  Spermatozoids,     ....... 

8.5.  Forms  of  Spermatozoids  in  various  Animals, 

86.  Ovum  of  Rabbit,  ...... 

87.  Transverse  Section  of  Human  Ovary  (low  power), 

88.  Cortex  of  Ovary  of  Eabbit,  .... 
8!).  Diagram  showing  Origin  of  Germ  Epithelium,  . 
no.  Section    of    Cortex   of    Ovary   showing    Germ 

Epithelium, 

ni.  Graafian  FolUcle, 

!)2.  Fecundation  of  Eggs  of  Asterias  glacialis,  . 

93.  Extrusion  of  Polar  Body  from  Egg  of  Succinea 

Pfeifferi 

94.  Diagrams   of  Extrusion   of    Polar    Body   from 

Asterias  Glacialis, 

95.  Diagram  showing  :\Iode  of  Nuclear  Divi^ian, 

96.  Egg  of  x\.scaris  megalocephala,  showing  Y-shaped 

Body 

97.  The  Y-shaped  Body 

98.  The  Y-shaped  Body,    .  , 

99.  Formation  of  First  Polar  Body, 

100.  Various  Forms  of  Ova  showing  Micropyle, 

101.  Ripe  Egg  of  Echinus, 

102.  Fecundated  Egg  of  Echinus,        .         •        .         . 

103.  Fecundated  Egg  of  Echinus  showing  Pronuclei, 

104.  Egg  of  Echinus  immediately  after  Fecundation, 

105.  Chromatin  Filaments  in  Egg  of  Ascaris  megalo 

cephala, 

106.  Division  of  Egg  of  Ascaris  megalocephala , 

107.  Di\dsion  of  Egg  of  Ascaris  megalocephala. 

108.  Egg  of  Echinus  preparatory  to  Cleavage. 

109.  Egg  of  Echinus  at  Moment  of  Division . 

110.  Egg  of  Echinus  after  Division,    . 

111.  Diagram   showing   Cleavage    of    Egg    to 

Embryonal  Cells,  ..... 

112.  Chromatin  Loops    in   Egg   of  Ascaris   megalo 

cephala,  ...... 

113.  Longitudinal  Section  of  Amphioxus, 

114.  Longitudinal   Section    through    Blastoderm   of 

Hen's  Egg  at  end  of  first  hour, 

115.  Diagrams  showing  Three  Layers  of  Blastoderm 

116.  Transverse  Section  through  Embryo  of  Newt, 

117.  Diagram  showing  Formation  of  Mesoblast, 

118.  Diagram  showing  Formation  of  Mesoblast, 

119.  Transverse   Section   through    Embryo   of    Am 

phioxus,  ...... 

120.  Blastodermic  Vesicle  of  Ribbit, 

121.  Section  of  Huyghenian  Eye-piece. 

122.  Section  of  Achromatic  Objective, 

123.  Leitz's  Microscope, 

124.  Zeiss'  Microscope, 

125.  Abbe's  Condenser, 

126.  Section  of  Abbe's  Condenser, 


Smhr,  . 
Stiihr,  . 

Patrick  Gedden, 
Waldeiier,    . 
Stohr,  .       .  . 
StiJhr,  . 
Hensev, 

Stohr,  . 
Stohr,  . 
Fol,      . 


Biltschli, 

Patrick    Geddes,   after 

and  Hcrtioiii, 
Ball,    . 


E.  van  Beneden, 
E.  van  Beneden, 
E.  van  Beneden, 
E.  van  Beneden. 
Hensen, 
0.  Jlertiviii, 
0.  Hertwig, 
O.  Hertivi'i, 
0.  Hertwiij, 


form 


E.  van  Beneden, 
E.  van  Beneden, 

E.  ran  Beneden, 
O.  Hertwig, 
0.  Hertioig, 
0.  Herticig, 

F.  M.  Balfour,  after 

haur,     . 


E.  ran  Beneden, 
0.  Hertwig, 


O.  Hertwig, 
0.  Hertwig, 
O.  Hertwig, 
0.  Hertwig, 
O.  Herttoig, 


O.  Hertwig, 
Von  KoUiker, 
Gscheidlen,  . 
Gscheidlen,  . 
Stohr,  . 


Fol 


Gegcii- 


LIST  OF  ILLUSTRATIONS. 


XXI 


127.  Diaphragm  of  Microscope,  .... 

128.  Abbe's  Camera  Lucida,       .... 

129.  Rutherford's  Microtome  arranged  for  Freezin; 

with  Ice  and  Salt,  .... 

130.  Rutherford's    Microtome    arranged    for    Ether 

Spray, 

131.  Roy's  Microtome,        ..... 


132.  Sliding  Microtome, 

133.  Rivet's  Microtome, 

134.  Rocking  Microtome, 


135. 
136. 
1.37. 

138. 

139. 

140. 

141. 
142. 
143. 
144. 
145. 
146. 
147. 
148. 
149. 
150. 
151. 
152. 
153. 
1.54. 

155. 
156. 
157. 
158. 
159. 
160. 
161. 

162. 

163. 
164. 
165. 
166. 
167. 


Cells  of  Tradescantia,  .... 

Hot  Stage,  ....... 

Arrangement  for  Electrical  Stimulation  of  Mi 

croscopic  Objects,  ..... 
Arrangement  for  Electrical  Stimulation  of  Mi 

croscopic  Objects,  ..... 
Arrangement   for   Observing   Action   of    Gases 

and  Vapours  on  Living  Tissues,     . 
^Vi-rangement  for   Observing  Action    of    Gase; 

and  Vapours  on  Living  Tissues,     . 
Von  Recklinghausen's  Moist  Chamber, 
Leucocytes  in  Frog's  Blood, 
Drop  of  Saliva,    ...... 

Secreting  Epithelial  Cells,  .... 

Section  of  Human  Sub-lingual  Gland, 
Blood  Corpuscles,         ..... 

Epithelial  Cells, 

Spinous,  Bristle,  or  Furrowed  Cells,  . 

Bristle  Cells, 

Pigment  Epithelium  of  Retina,  .         .         . 

Simple  Cylindrical  Epithelium,  . 

Stratified  Pavement  Epithelium, 

Stratified  Ciliated  Epithelium,    . 

Endothelial  Cells  in  Serous  Membrane  of  Dia 

IDhragm,  ...... 

Cells  with  Foreign  Matters  in  their  Protoplasm, 
Fatty  or  Adipose  Tissue  and  Fat  Cells, 
Involuntary  Muscle  from  Frog's  Intestine, 
Striated  Muscle  of  Frog,      .... 

Polarizer  for  Microscope,     .... 

Analyzer  for  Microscope,     .... 

Diagram    showing   Hypothetical  Views    as    to 

Structure  of  Muscle,      .... 
Living  Muscular  Fibre  from  Geotrupes  Stereo 

rarius,    ....... 

Same  Fibre  as  162  seen  with  Polarized  Light, 
Muscular  Fibre  from  Hydrophilus  Piscejis, 
Muscular  Fibre  from  Geotrupes  Stercorarius, 
Same  Fibre  as  165  seen  with  Polarized  Light, 
Muscular   Fibre   from   Geotrupes   Stercorarius 

showing  rod-like  Striictures, 


Gscheidlen,  . 


PAGE 

.258 
2.59 


Paitlierford, 

Rutherford, 

Cambridge  Scientific  Instru- 
ment Company,     . 
Gscheidlen,  .        .        .        . 


Cambridge  Scieiitific  Instru- 
ment Company,     . 
Kiihne, 
Gscheidlen, 

Gscheidlen, 

Gscheidlen, 

Gscheidlen, 

Gscheidlen, 
Gscheidlen, 
Stohr,  . 


Stuhr,  . 
Stohr,  . 
Stohr,  . 
Stohr,  . 
Frey,  . 
Stohr,  . 
Stiihr,  . 
Stohr,  . 
Stohr,  . 
Stohr,  . 

Frey,  . 
Frey,  . 
Stohr,  . 
Stohr,  . 
Stohr,  . 
Gscheidlen, 
Gscheidlen, 


Van  Gehuchten, 
Van  Gehuchten, 


Van  Gehuchten, 


Van  Gehuchten, 


279 

281 

282 
283 

.284 

285 
289 
290 

291 

291 

291 

292 
292 
295 
296 
297 
298 
300 
.301 
302 
302 
302 
302 
303 
304 

304 
304 
305 
306 
307 
308 
308 

309 

310 
310 
310 
311 
311 

311 


XXIV 


LIST  OF  ILLUSTRATIONS. 


Tracing     according     to     Marey's 


of 


253.  Myograjiliic 

Method, 

254.  Marey's  Tambour 

255.  Marey's  Tambours  arranged  for  Transmission 

Movement,      ...... 

256.  Arrangement  of  Mai-ey's  Tambours  for  recordin; 

Three  Movements,  .... 

257.  Transmission  of  Muscular  ilovements  by  Tarn 

hours,     ....... 

258.  Record  of  Tuning- Fork  ^'ibrations  transmitted 

by  Tambours,  ..... 

259.  Tracings   of   Movements   of    Fontanelle    trans 

mittcd  by  Tambours,     .         .         . 

260.  Hypodermic  Sj^ringe,  .... 

261.  Xerve  Muscle  Preparation, 

262.  Muscle  Telegraph, 

263.  Curve  of  ]\hiscular  Contraction  produced  by  ; 

Single  Induction  Shock, 

264.  Pendulum  Myograph,  .... 

265.  Break  Ajjparatus  of  Pendulum  Myograph, 

266.  Tracing  with  Pendulum  Myograph,    . 

267.  Travelling  Stage  of  Marey,  ... 

268.  Arrangement   for  recording  Consecutive    Con 

tractions  of  a  Frog's  Gastrocnemius, 

269.  Tracings  of  Muscular  Contractions,     . 

270.  Apparatus  for  recording  the  Curve  of  Thicken 

ing  of  a  Muscle 

271.  Arrangement  for  Tracing  the  AYave  of  Muscular 

Contraction, 

272.  Tracing   of   the   Propagation   of   the   Muscular 

Wave, 

273.  Cm'ves  showing  the  Rapidity   of    the    Trans 

mission  of  the  Wave  of  Contraction, 

274.  Curve  of  Tetanus, 

275.  Curve  showing  Genesis  of  Tetanus,     . 

276.  Tracing  of  a  Double  Muscle  Curve,     . 

277.  Curve  showing  the  Genesis  of  Tetanus, 

278.  Curve  showing  the  Genesis  of  Tetanus, 

279.  Arrangement  for  Studying  the  Action  of  Heat 

on  a  Frog's  Heart, 

280.  Heidenhain's  Arrangement    for    Studying    the 
Heat  Phenomena  of  Muscle, 

Diagram  of  Muscle  "Work,  . 

Dynamometer,     .... 

Tracing  showing  Muscular  Fatigue, 

Tracing    of    the    Contraction   of    Non-Striated 

Muscle, 

Magnet  of  Wiedemann's  Boussole, 

286.  Wiedemann's  Boussole, 

287.  Du  Bois-Eeymond's  Arrangement  of  Hauy's  Bar 

for  Wiedemann's  Boussole,    . 

288.  Magnet  and  Mirror  of  ATiedemann's  Boussole, 

289.  Eeflecting  Galvanometer  of  Sir  William  Thomson, 


281. 
282. 
283. 
284. 

285. 


Ci/on, 
Cijon, 

Foster, 

Ciion, 

Cyan, 


Marey, 

Marey, 
]\Iarey, 

Marey, 

Marey, 


Marey, 


Foster, 


Ciion, 


Marey, 

Paul  Bert, 
Cyon,  . 
Cyan,  . 

Cyon,  . 


LIST  OF  ILLUSTRATIONS. 


XXV 


290.  Lippmann's  Capillary  Electrometer,  . 

291.  Appearance  of  the  Capillary  Tube  in  Lippmann's 

Caj)illary  Electrometer,  .... 

292.  Photograph  of  Oscillations  of  Capillary  Electro- 

meter,   ........ 

293.  Du  Eois-Eeymond's  Non-Polarizable  Electrodes, 

294.  Diagram  of  Arrangement  of  Du  Bois-Eeymond's 

Non-Polarizable  Electrodes,  .... 

295.  Non-Polarizable  Electrodes,         .... 

296.  Engelmann's  Non-Polarizable  Electrodes,   . 

297.  ^Vrrangement  for  Measuring  e.  m.  f.  of  a  Section 

of  Muscle,       ....... 

298.  Du  Bois-Reymond's  Rheochord, 

299.  Diagram   showing    Method    of    Demonstrating 

Matteucci's  Induced  Contraction, 

300.  Matteucci's  Induced  Contraction, 

301.  Hermann's  Rheotome,  .         >         .         .         . 

302.  Du  Bois-Reymond's  Electromotive  Molecules,    . 

303.  Hermann's  Fall  Rheotome,  .... 

304.  Diagram  showing  the  Arrangement  of  the  Fall 

Rheotome,      ....... 

30-5.  Torpedo  Galvani,         ...... 

306.  Nerve-Tuft  in  Torpedo, 

307.  Terminations  of  Nerve  on  the  Plate  of  Torpedo, 

308.  Diagram  of  Prism  of  Torpedo,     .... 

309.  Electric  Plates  of  Torpedo,  .... 

310.  Section  through  Electric  Plate  of  Gymnotus,     . 

311.  Transverse  Section  of  Spinal  Cord  of  Gymnotus, 

312.  Electric  Nerve  Cell  of  Gymnotus, 

313.  Portion  of  Electric  Organ  of  Malapteriirus, 

314.  Diagram  of  Electric  Organ  of  common  Skate,    . 
31.5.  Semi-diagrammatic  View  of  Disc  from  Electric 

Organ  of  common  Skate,        .... 

316.  Diagram  showing  the  Current  Curves  in  Electric 

Discharge  of  Torpedo, 

317.  Motorial  End-plate  in  Muscle,     .... 

318.  Mode  of  Nerve-endings  in  Glands, 


Marty, 


Gscheidlen, 


C>/on,  . 

M'Gregor-Rohertson, 
Cyon,  . 


Bur  don- Sanderson, 
Bur  don- Sanderson, 


Ewald, 

Eivald, 

Eioald, 

Ranvicr, 

Friisch, 

Fritscli, 

Fritsch, 

Fritscli, 

Burdon-Sanderson 


Bur  don-Sander  son, 
Burdon-Sanderson, 
PJiiiger, 


PAGE 

444 
445 

445 

446 

447 
449 
449 

450 
451 

453 
453 
454 
456 
457 

.  458 

.  462 

.  463 

.  463 

.  463 

.  464 

.  466 

.  467 

.  468 

.  469 

.  470 

.     471 

.  481 
.  484 
.     484 


ERRATA. 

Page  55,  line  8  from  bottom,  for  Amines  read  Amides. 

Page  225,  line  1  from  top,  for  expression  read  extrusion. 

Page  310,  line  4  from  bottom,  before  Marshall  inseH  Melland  and. 


TEXT    BOOK    OF    PHYSIOLOGY. 

SECTION  I. 

GENERAL   INTRODUCTION. 

Chap.  I.— NATURE  AND  OBJECTS  OF  PHYSIOLOGY. 

Physiology  is  the  science  which  treats  of  the  phenomena  normally 
occurring  in  living  things.  It  is  divided  into  Vegetable  and  Animal 
Physiology,  according  as  the  life-history  of  plant  or  of  animal  is 
made  the  subject  of  consideration.  Human  Physiology,  a  depart- 
ment of  the  science  which  forms  the  special  subject  of  this  treatise, 
concerns  itself  with  the  phenomena  occurring  in  man. 

The  physiology  of  man,  or  indeed  of  any  living  being,  cannot  be 
studied  with  success  if  we  regard  merely  the  changes  happening 
in  the  body  of  an  individual,  or  even  if  we  attend  only  to  the 
phenomena  of  the  species  as  a  whole;  for  much  of  our  knowledge 
depends  on  the  study  of  operations  occurring  in  a  great  variety  of 
living  beings. 

When  we  contemplate  any  living  being,  we  observe,  first,  a 
peculiar  physical  structure  or  conformation  of  the  solid  parts  ; 
second,  a  determinate  chemical  composition  of  its  several  solid  and 
fluid  parts;  and,  third,  the  occurrence  of  certain  chemical,  physical, 
and  vital  changes. 

In  the  physical  structure  of  the  body,  certain  parts  may  be 
readily  isolated,  and  these  may  each  perform  a  special  office  in  the 
economy.  Such  parts  are  termed  organs,  and  the  office  which  each 
organ  performs  is  called  its  function.  Life,  so  far  as  the  individual 
is  concerned,  may  be  said  to  be  "the  sum  of  the  several  functions 
performed  by  the  various  organs,  or  the  active  state  resulting  from 
their  concurrent  exercise."     (Allen  Thomson.) 

The  body  may  be  studied  both  in  the  dead  and  in  the  living 
condition.  In  the  dead  state  its  structure  and  composition  are  the 
subjects  of  anatomical  and  of  chemical  research  The  living  state 
I.  A 


2  INTRODUCTION. 

is  more  especially  the  })ro^^nce  of  the  i)liysiologist,  it  being  his 
duty  to  study  the  functions,  or  the  various  phenomena  manifested 
by  the  organs  incliA'idually,  and  as  part  of  a  system,  during  life. 

The  economy  of  the  human  body  is  one  of  great  complexity, 
and  in  its  study  the  physiologist  finds  it  necessary  to  extend  his 
investigations  over  a  wide  field.  His  information  is  derived  partly 
from  observation  and  experiments  made  directly  upon  man  himself, 
both  in  the  healthy  and  in  the  diseased  conditions,  but  very  largely 
also  from  investigations  into  the  functions  performed  by  the  organs 
of  other  animals.  Many  of  the  facts  of  phj'siology  with  which  w(; 
are  at  present  acquainted  have  been  derived  from  observations  and 
experiments  made  on  the  humbler  animals,  but  the  apparently 
identical  nature  of  many  vital  actions,  more  especially  as  mani- 
fested by  the  elementaiy  tissues  and  in  the  simpler  organs,  and  the 
general  plan  of  structure  on  which  organs  are  formed  throughout  the 
range  of  the  animal  kingdom,  warrant  us  in  applying  these  facts 
generall}^  to  the  elucidation  of  the  functions  of  the  human  body. 

Physiology  derives  its  facts  from  the  observation  of  the  phenomena 
of  li'vang  beings,  made  ^nth  scientific  accurac}^  and  aided  by  deduc- 
tions from  facts  belonging  to  other  branches  of  science,  more 
especially  anatomy,  chemistry,  and  physics.  A  general  acquaintance, 
therefore,  Avith  these  sciences  is  of  paramount  importance  to  anyone 
about  to  enter  upon  the  study  of  physiology. 

The  student  ought,  in  the  first  instance,  to  be  acquainted  with  the 
structure  of  the  human  body  and  of  its  various  organs,  and  he  should 
also  be  familiar  Anth  the  general  plan  of  structure  met  A\dth  in  the 
great  general  subdivisions  of  the  animal  kingdom.  Such  anatomical 
knowledge  {Human  and  Comparative  Anatomy)  must  be  obtained  by 
dissection  and  by  a  careful  comparison  of  organs  in  different  groups 
of  animals. 

During  the  past  forty  years,  much  knowledge  has  been  accjuii-ed 
regarding  the  minute  structure  of  the  various  tissues  forming  the 
body.  This  constitutes  the  department  of  science  called  Histulofjij. 
As  many  functions  are  j^erformed  by  elements  of  the  body  which 
are  of  microscopic  size,  it  is  evident  that  we  must  be  accurately  ac- 
quainted \nih.  the  anatomical  structure  of  these  elements.  Such 
knowledge,  therefore,  belongs  equally  to  the  anatomist  and  to  the 
physiologist.  The  anatomist  must  describe  the  form,  size,  and  general 
relations  of  these  minute  parts,  while  the  physiologist  directs  his 
attention  specially  to  the  phenomena  they  manifest  Avhile  alive. 
Both  are  engaged  in  the  study  of  the  same  textural  elements,  but 
from  different  points  of  view — the  one  morphological,  the  other  physio- 


NATURE  AND  OBJECTS  OF  PHYSIOLOGY.  3 

logiail.  Here,  as  in  the  study  of  parts  visible  to  the  naked  eye, 
knowledge  of  structure  and  of  function  are  really,  in  the  language 
of  Goodsir,  different  aspects  of  the  same  truth. 

To  acquire  a  wide  knowledge  of  the  functions  of  the  body,  it  is 
not  sufficient  to  study  it,  even  as  regards  its  structure,  only  in  its 
full-grown  or  mature  condition.  It  is  necessary  to  examine  it  at 
various  stages  of  its  growth,  and  to  trace  minutely  the  first 
formation  and  early  development  of  the  embryo,  the  origin  of  the 
primary  tissues,  the  formation  of  the  more  complicated  organs  and 
systems  of  organs,  and  the  process  of  growth  of  the  foetus  and 
child.  This  research  is  designated  by  the  name  of  Embryology,  and 
in  recent  times  it  has  furnished  important  information  regard- 
ing the  history  and  bearing  of  vital  phenomena.  Embryology  may 
be  conveniently  divided  into  two  sections:  (1)  The  history  of  the 
development  of  any  single  organism  from  the  ovum  onwards  {Ontogeny); 
and  (2)  the  history  of  the  evolution  of  the  group  or  race  from  lower 
to  higher  forms  (Phylogeny).  Thus  comparative  embryology  has 
both  an  anatomical  and  a  physiological  side ;  on  the  anatomical  it  is 
the  basis  of  morphology,  or  all  that  relates  to  organic  form,  and  on 
the  physiological  it  gives  a  solution  of  many  of  the  problems  of  function. 

From  the  facts  and  laws  of  Chemistry  the  physiologist  derives  in- 
formation regarding  the  chemical  composition  of  the  solid  textures, 
as  well  as  of  the  various  secreted  and  circulating  fluids,  and  of  the 
variations  to  which  their  composition  is  subject  in  diff"erent  conditions 
of  the  body.  Physiological  chemistry  has  as  its  ultimate  aim  the  correct 
statement  and  explanation  of  the  chemical  processes  occurring  in  the 
body,  and  it  is  generally  regarded  as  the  most  difficult  department  of 
the  parent  science. 

The  laws  of  Physics  are  applied  by  the  physiologist  to  the  investiga- 
tion of  all  the  obvious  motions  of  solids  or  fluids  occurring  in  the 
animal  organism  and  also  to  the  explanation  of  those  molecular  changes 
of  which  a  physical  explanation  can  be  offered.  A  knowledge  of 
physics  is  indispensable  in  examining  the  functions  of  such  organs  of 
special  sense  as  the  eye  and  ear,  and  in  studying  the  influence  of 
light,  heat,  and  electricity,  in  modifying  vital  phenomena. 

It  may  further  be  remarked,  that  while  the  researches  of  the 
physiologist  are  directed  strictly  to  establishing  the  knowledge  of  the 
functions  of  the  living  economy  in  a  state  of  health,  he  not  unfre- 
quently  receives  assistance  from  the  pathologist  (Pathology),  who 
having  his  attention  called  to  the  organic  and  functional  changes  that 
occur  under  the  influence  of  different  forms  of  disease,  takes  advantage 
as  it  were  of  so  many  experiments  made  to  his  hand  by  nature,  and 


4  INTRODUCTION. 

is  thus  better  ahle  to  discriminate  the  share  which  each  particular 
condition  has  in  the  production  of  these  complex  results. 

The  physiological  study  of  the  functions  of  the  human  body  de- 
pends then  on  the  follo^\^ng  means  of  investigation,  viz.:  (1)  The 
observation  of  the  phenomena  of  the  body  in  a  healthy  state ;  (2)  The 
occasional  comparison  of  the  healthy  state  with  moi'bid  conditions  of 
the  economy;  (3)  The  experimental  variation  in  man  or  animals  of 
the  conditions  in  which  vital  operations  take  place ;  (4)  The  anatomi- 
cal examination,  by  dissection  and  microscopic  research,  of  the  structure 
of  the  organized  parts  of  the  body  at  various  stages  of  its  growth  or 
in  the  fully-formed  state,  or  as  found  in  a  simpler  condition  in  the 
bodies  of  the  lower  animals  or  even  in  plants ;  (5)  The  chemical 
analysis  of  the  solids  and  fluids,  and  of  the  substances  which  are 
taken  into  or  are  ejected  from  the  system,  and  the  history  of  the 
chemical  changes  which  occur  in  the  living  body ;  and  (6)  the  appli- 
cation of  the  facts  and  principles  of  physics  where  these  are  admissible. 

As  the  object  of  physiology  may  be  said  to  be  "to  ascertain  the 
conditions  of  bodj^  and  mind  which  are  necessary  to  life  and  health," 
so  the  most  important  practical  end  which  the  human  physiologist 
has  in  view  is  to  furnish  data  for  guiding  the  physician  in  detecting 
diseases  with  readiness,  in  distinguishing  their  different  kinds  Math 
accuracy,  in  endeavouring  to  preserve  health,  and  when  disease  shall 
have  occurred  to  allay  suffering  and  to  restore  the  natural  condition. 
A  knowledge  of  the  conditions  of  health  must  precede  the  study  of 
disease,  and  a  rational  system  of  surgical  and  medical  treatment  has 
its  foundation  in  an  acquaintance  Avith  the  principles  of  physiology. 
But,  apart  from  its  practical  aspect,  physiology  considered  as  a  pure 
science,  presents  an  attractive  field  of  study,  taking  a  A\ade  range 
over  the  domain  of  nature  and  bringing  the  mind  into  the  contempla- 
tion of  some  of  the  most  profound  problems  and  of  some  of  the  most 
sublime  truths. 

Chap.  II.— MATTER  AND  ENERGY. 

The  permanence  of  matter  and  the  permanence  of  energy  are  two 
great  generalizations  which  form  the  groundwork  of  physical  science, 
and  they  must  be  recognized  in  dealing  "\vith  the  phenomena  of  the 
living  body  just  as  clearly  as  in  considering  the  facts  of  chemistry 
and  physics. 

1.  Matter. — In  its  jDassage  through  the  living  body  matter  cannot 
be  created  or  destroyed ;  if  it  apparently  disappears  it  is  only  trans- 
formed into  another  condition.     It  need  hardly  be  said  that  chemistry 


MATTER  AND  ENERGY.  5 

only  became  an  exact  science  when  the  permanence  of  matter  was 
recognized.  No  portion  of  matter,  however  minute,  can  either  come 
into  existence  or  go  out  of  existence  in  any  chemical  operation.  The 
study  of  the  chemical  transformations  in  or  by  a  living  body  is  an 
important  branch  of  physiology,  and  it  is  becoming  more  and  more  the 
aim  of  physiologists  to  obtain  quantitative  as  well  as  qualitative  results, 
feeling  assured  that  as  they  succeed  in  doing  so,  will  they  bring  their 
science  nearer  to  the  platform  of  physics  and  of  chemistry.  Measuring 
and  weighing  in  units  of  length,  time,  volume,  and  mass  are  operations 
as  important  in  physiology  as  in  physics. 

As  the  metric  system  is  now  in  use  over  the  greater  part  of  Europe 
and  is  spreading  in  America,  it  should  be  uniformly  adopted  in  Great 
Britain,  at  all  events  in  scientific  literature,  and  I  would  strongly  re- 
commend the  student  to  become  familiar  with  it.  To  assist  him,  I 
give  the  following  short  resume  for  reference  : — 

1.  Length. — One  metre  is  equal  to  39-371  inches,  1  foot  is  equal 
to  30 '48  centimetres,  and  1  inch  is  equal  to  2  5 '4  millimetres.  It  may 
be  noted  that  in  the  metric  system  the  Latin  prefixes  denote  division 
and  the  Greek  prefixes  denote  multiplication.  Thus  decimetre,  centi- 
metre, millimetre,  and  micrometre  denote  the  tenth,  the  hundredth, 
the  thousandth,  and  the  millionth  of  a  metre  respectively;  and 
decametre,  hectometre,  and  kilometre  denote  ten,  a  hundred, 
and  a  thousand  metres.  These  measures  may  also  be  squared  or 
cubed.      In   Fig.    1,  4   inches   are   placed   alongside   of    1    decimetre. 


3  Z 


d 


Fig.  1. — Comparison  of  a  decimetre  with  4  inches  :  a,  centimetres ; 
i,  millimeti-es  ;  c,  -|ths  of  an  inch ;  d,  inches. 

The  micron,  /x,  the  loVotli  of  a  millimetre  =  -001  mm.  and  is  now 
used  in  the  measurement  of  objects  of  microscopic  size :  thus,  the 
average  diameter  of  the  red  blood  corpuscles  in  man  is  77  /x  or  '077 
mm. 

2.  Time. — The  unit  of  time  is  the  mean  solar  second.  In  many 
physiological  observations,  fractions  of  a  second,  hundredths,  or  even 
thousandths,  must  be  accurately  determined  by  means  of  specially 
designed  chronographs.     (See  Graphic  Method.) 

3.  Mass  and  Weight. — In  the  metric  system  the  unit  of  mass  is  1 
gramme,  which  is  the  mass  (or  weight)  of  a  cubic  centimetre  of  water 


INTRODUCTION. 


Fig.  2.— Square 
Centimetre. 


Via.  3.— Cubic 
Centimetre. 


Fio.  4.— Balance. 


MATTER  AND  ENERGY.  7 

at  its  temperature  of  maximum  density,  4°  C.  (See  Figs.  2  and  3.) 
One  gramme  is  equal  to  15-4321  grains  avoirdupois.  It  is  also  con- 
venient to  remember  that  if  we  compare  imperial  units  (Avoirdupois) 
Avith  the  metric  system,  1  grain  =  yoV-o  pound  =  -0648  gramme  ;  1 
dram  -  ^\-q  pound  ;  1  ounce  (16  drams)  =  y'gth  pound  =  28*35  grammes  ; 
1  pound  (lb.)  =  -4536  kilog.  In  Troy  weight,  1  ounce  —  480  grains  = 
31*10  grammes,  and  in  Apothecaries'  weight,  1  scruple  =  20  grains, 
1  drachm  =  3  scruples,  and  1  ounce  =  8  drachms.  In  weighing,  a  good 
balance  is  indispensable.  (See  Fig.  4.)  It  consists  of  a  light  rigid 
beam  resting  on  a  fixed  horizontal  axis  at  its  centre.  A  scale-pan 
is  hung  at .  each  end  of  the  beam,  one  to  receive  the  standard  weight 
and  the  other  to  receive  the  body  to  be  weighed.  When  there  are 
no  weights  in  the  scale-pans,  or  when  these  contain  equal  weights, 
the  beam  is  horizontal.  Both  the  beam  and  the  scale-pans  are  sus- 
pended on  agate  knife-edges  working  on  agate  planes.  A  good  balance, 
loaded  with  a  kilogramme  in  each  pan,  will  turn  with  -0007  gramme, 
or  about  i^oio-o"oth  of  the  weight  in  either  pan.  The  weights  are 
kept  in  a  suitable  box,  as  seen  in  Fig.  5. 


FiQ.  5. —  Box  of  Weights. 

4.  Volume.—  The  unit  of  volume  in  the  metric  system  is  1  cubic 
centimetre.  In  this  connection  it  may  be  noted  that  1  pint  =  "568 
litre  (the  litre  being  the  capacity  of  1  cubic  decimetre) ;  1  quart  = 
1*136  litre;  1  gallon  -  4*544  litres;  1  litre  = -22  gallon;  1  fluid 
ounce  (in  sale  of  drugs)  =  1*8  cubic  inch,  or  *0284  litre;  1  cubic 
foot  =  *02831   cubic  metre;    and    1    cubic   metre  =  1*308    cubic   yard. 


8 


INTRODUCTION. 


The  A-olunu!  of  Huids  is  measured  liy  flasks  having  a  capacity  when 
filled  up  to  a  mark  on  the  neck  of  from  100  to  2,000  cubic  centi- 
metres (Fig.  6) ;  by  graduated  cylindrical  glasses,  as  shown  in  Fig.  7  ; 
or  by  graduated  pipettes,  as  in  Figs.  8  and  9. 


Fig.  6.— Litre  flask, 
J  nat.  size. 


25CC 


10  CC 


Fig.  S.— Pipette 
for  10  cb.  cm.,  i 
nat.  size. 


Fio.  7.— Flask,  iliiiit.  size, 
graduated  for  100  ub.  cm. 


Fio.  9.— Pi- 
pette, for  25 
ob.  cm.,  J 
nat.  size. 


The  knowledge  of  the  physiologist  regarding  the  molecular  phenomena 
occurring  in  living  things  is  stiU  so  imperfect  that  he  has  no  occasion 
to  follow  the  physicist  in  his  speculations  as  to  the  ultimate  nature  of 
matter.  The  atomic  theory  of  Democritus  and  Leucippus  "glorified," 
as  Professor  Tait  writes,  "in  the  grand  poem  of  Lucretius,"  Newtonls 
conception  of  hard,  finite  atoms,  the  substitution  by  Boscovitch  for 


MATTER  AND  ENERGY.  9 

the  material  atom  of  a  mathematical  point,  "towards  or  from  which 
certain  forces  tend,"  or  the  splendid  vortex-atom  hypothesis  of  Sir 
William  Thomson,  in  which  "  matter,  such  as  we  perceive  it,  is  merely 
the  rotating  parts  of  a  fluid  which  fills  all  space,"  throws  no  light  at 
present  on  vital  phenomena,  except  in  so  far  as  these  can  be  brought 
within  the  domain  of  physical  science.  It  is  possible,  however,  to 
conceive  that  certain  vital  phenomena  may  be  due,  in  their  essence, 
to  special  properties  inherent  in  the  constitution  of  matter,  but  the 
physiologist  is  still  far  from  the  discussion  of  such  questions.  He 
finds  that  living  matter  is  composed  of  certain  solid,  liquid,  or  gaseous 
constituents,  and  that  it  is  the  assemblage  of  these  in  varying  propor- 
tions that  gives  to  living  matter  its  peculiar  properties.  The  pheno- 
mena of  life  are  never  manifested  by  solid,  liquid,  or  gaseous  matter 
individually,  but  only  when  matter  is  in  a  peculiar  colloidal  condition 
or  mass  which,  when  death  occurs,  will  split  up  into  solid,  liquid, 
and  gaseous  substances.  At  the  same  time,  it  is  becoming  more  and 
more  evident  that  vital  actions  such  as  growth,  secretion,  and  the 
contraction  of  living  muscle,  depend  on  molecular,  it  may  be,  atomic 
changes  occurring  in  living  matter,  changes  as  much  beyond  direct 
inspection  as  the  molecular  movements  in  a  conductor  of  electricity, 
or  in  the  isomeric  transformation  of  cyanate  of  ammonia  into  urea. 

2.  Energy. — Physiology,  in  common  with  the  science  of  physics 
and  of  chemistry,  has  received  a  strong  impetus  towards  exactitude 
and  comprehensiveness  from  modern  generalizations  regarding  energy. 
The  term  energy  must  be  clearly  distinguished  from  the  term  force, 
and  before  entering  into  a  consideration  of  energy  we  must  under- 
stand clearly  what  is  meant  by  the  terms  force  and  work.  The  notion 
of  force  is  suggested  by  the  sensation  of  pressure  or  of  resistance 
experienced  when  we  move  a  body  with  the  hand  or  foot,  as  in  lifting 
a  weight  from  the  floor  to  the  table,  but  it  will  be  observed  that  this 
is  merely  a  sensation  or  feeling  due  to  what  is  termed  the  muscular 
sense  and  that  we  must  distinguish  between  the  sensation  and  the 
cause  of  the  sensation.  Suppose  the  muscular  sense  perverted  by 
disease,  the  weight  might  still  be  lifted  from  the  floor  to  the  table, 
but  our  notions  of  the  force  would  be  quite  different.  There  is  no 
proof  then  of  the  objective  reality  of  force.  But  the  weight  has  been 
lifted  from  the  floor  to  the  table  and  there  has  been  a  transference  of 
what  is  called  energy  from  one  portion  of  matter  (the  muscles  of  the 
arm  and  body)  to  another  (the  weight  resting  on  the  table).  "  When- 
ever such  a  transference  takes  place,  there  is  a  relative  motion  of  the 
portions  of  matter  concerned,  and  the  so-called  force  in  any  direction 
is  merely  the  rate  of  transference,  or  of  transformation,  of  energy  per 


10  INTRODUCTION. 

imit  of  length  for  displacement  in  that  direction."  (Tait,  Recent 
Advances  in  Physical  Science,  p.  16.)  Force,  then,  is  rate  of  transfor- 
mation of  cnerg}'  in  time.  The  British  unit  of  force  is  the  "poundal," 
defined  as  that  force  which  applied  to  one  pound  of  matter 
for  one  second  generates  in  it  a  velocity  of  one  foot  per  second.  In 
the  centimetre-gramme-second  system  (c.G.s.),  the  imit  of  force  is  the 
"dyne,"  similarly  defined  as  that  force  which,  acting  on  one 
gramme  for  one  second,  generates  in  it  a  velocity  of  one  centimetre 
per  second. 

The  next  conception  it  is  important  clearly  to  grasp  is  that  of  IFc/rk. 
Work  is  done  when  resistance  is  overcome,  and  the  quantity  of  work 
done  is  measured  by  the  prodiict  of  the  resisting  force  and  the  distance 
through  Avhich  it  is  overcome,  in  the  direction  in  which  the  force  acts. 
The  British  absolute  unit  of  work  is  the  "foot-poundal,"  which  is  the 
work  done  by  a  poundal  acting  through  a  foot.  The  al)solute  unit  of 
work  on  the  metrical  system  is  the  "erg,"  which  is  the  work  done  by  a 
dyne  acting  through  a  centimetre.  Again,  work  may  be  measured  in 
gravitation-units — the  British  being  the  "foot-pound,"  which  is  the 
work  required  to  overcome  a  force  equal  to  the  weight  of  a  pound 
through  the  space  of  a  foot ;  the  unit  in  the  metrical  system  being  the 
"  centimetre-gramme,"  defined  as  that  required  to  overcome  a  force  equal 
to  the  weight  of  one  gramme  acting  through  the  space  of  one  centimetre. 
In  the  study  of  the  Avork  done  by  a  contracting  muscle,  the  unit  usually 
employed  is  the  "millimetre-gramme,"  similarly  defined. 

We  are  now  in  a  position  to  understand  what  is  meant  by  saying  that 
Energy  is  the  power  or  capacity  of  doing  work.  When  a  weight 
is  lifted  from  the  floor  to  the  table,  work  is  done  in  overcoming  the 
attraction  between  the  earth  and  the  weight,  and  the  energy  of  the 
system — the  earth  and  the  weight — is  increased.  The  weight  on  the 
table  is  now  in  a  position  to  do  work ;  for  example,  it  might,  by  proper 
arrangements,  be  allowed  to  descend  slowly,  as  the  weight  of  a  clock,  and 
do  work  in  overcoming  the  friction  of  the  wheels,  the  resistance  of  the 
air  to  the  motion  of  the  pendulum,  and  in  giving  rise  to  the  waves  of 
sound  by  which  we  might  hear  the  ticking  of  the  clock.  Before  it  begins 
to  descend,  the  weight  possesses  Potential  Energy,  or  energy  of  position. 
A  bent  boAv,  a  coiled  mainspring  of  a  Avatch,  a  head  of  water,  are 
familiar  instances  of  this  kind  of  energy.  Another  mode  of  energy  is 
the  energy  of  motion  or  Kinetic  energy.  Thus,  suppose  a  certain 
amount  of  work  is  clone  in  lifting  a  weight,  the  weight  acquires  energy 
of  position  (potential) ;  if  it  be  now  allowed  to  fall  to  the  ground  its 
energy  of  position  is  gradually  transformed  into  energy  of  motion 
(kinetic),  and  it  can  be  shoAvm  that  "the  amount  of  potential  energy  lost 


MATTER  AND  ENERGY.  11 

in  every  stage  of  the  operation  is  precisely  equal  to  the  amount  of 
kinetic  energy  gained."  (Tait,  op.  cit.  p.  19.)  It  follows  from  this  that 
energy,  like  matter,  can  neither  be  created  nor  destroyed.  It  may  dis 
appear,  but  there  has  only  been  a  transference  from  one  material  thing, 
or  system  of  material  things,  to  another.  It  may  suddenly  appear,  but 
it  has  not  originated  de  novo :  it  has  appeared  at  the  cost  of  potential 
energy  somewhere  else.  Further,  it  is  known  that  when  a  transfor- 
mation of  energy  takes  place  "  there  is  always  a  tendency  to  pass,  at  least 
in  part,  from  a  higher  or  more  easily  transformable  to  a  lower  or  less 
easily  transformable  form."     (Tait,  op.  cit.  p.  20.) 

The  doctrine  of  the  Conservation  of  Energy  asserts,  in  the  language  of 
Clerk  Maxwell,  "The  total  energy  of  any  material  system  is  a  quantity 
Avhich  can  neither  be  increased  nor  diminished  by  any  action  between 
the  parts  of  the  system,  though  it  may  be  transformed  into  any  of  the 
forms  of  which  energy  is  susceptible."  (Clerk  Maxwell's  Matter  and 
Motion,  p.  60 ;  also  proved  by  Von  Helmholtz.)  This  great  doctrine 
was  enunciated  after  much  speculation,  calculation,  and  experiment,  "with 
regard  to  the  nature  of  heat.  So  long  ago  as  the  beginning  of  the  1 8th  cen- 
tury Locke  wrote  the  following  passage :  "Heat  is  a  very  brisk  agitation  of 
the  insensible  parts  of  the  object,  which  produces  in  us  that  sensation 
from  which  we  denominate  the  object  hot ;  so  what  in  our  sensation  is 
heat,  in  the  object  is  nothing  but  motion."  (John  Locke,  Natural  Philo- 
sophy, 1706.)  Professor  Tait  shows  {op.  cit.  Lecture  II.)  that  Sir  Isaac 
NeAvton  was  in  possession  of  many  of  the  facts  of  the  conservation  and 
transformation  of  energy.  Count  Rumford  demonstrated  "that  the  great 
quantity  of  heat  excited  by  the  boring  of  cannon  could  not  be  ascribed 
to  a  change  taking  place  in  the  calorific  capacity  of  the  metal,  and  he 
therefore  concluded  that  the  motion  of  the  borer  was  communicated  to 
the  particles  of  the  metal,  thus  producing  the  phenomena  of  heat.  '  It 
appears  to  me,'  he  remarks,  '  extremely  difficult,  if  not  quite  impossible, 
to  form  any  distinct  idea  of  anything  capable  of  being  excited  and  com- 
municated in  the  manner  the  heat  was  excited  and  communicated  in  these 
experiments,  except  it  be  motion.' "  Sir  Humphry  Davy,  sometime  after 
the  date  1799,  showed  that  by  rubbing  two  pieces  of  ice  against  one  another 
in  the  vacuum  of  an  air  pump,  part  of  the  ice  was  melted,  although  the 
temperature  of  the  receiver  was  kept  below  the  freezing  point,  and  he 
inferred  that  "the  immediate  cause  of  the  phenomena  of  heat  is  motion, 
and  the  laws  of  its  communication  are  precisely  the  same  as  the  laws  of 
the  communication  of  motion."  (Davy's  Elements  of  Chemical  Philosophy, 
p.  94.)  In  1834,  Faraday  discovered  important  relations  existing 
between  magnetism,  electricity,  and  light.  In  1840,  Joule  showed,  "1st, 
that  the  heat  evolved  by  any  voltaic  pair  is  proportional,  cceferis  paribus, 


12  INTRODUVriON. 

to  its  intensity  or  electro-motive  force ;  aiul,  2n(l,  that  the  heat  evolved 
hy  the  combustion  of  a  hody  is  pro^jortioual  to  the  intensity  of  its 
affinity  for  oxygen,"  thus  establishing  relations  between  heat  and  chemical 
affinity.  Similarly,  in  1843,  Joule  showed  relations  between  magneto- 
electricity  and  heat;  and  in  1844,  he  proved  "that  the  heat  absorbed 
and  evolved  by  the  rarefaction  and  condensation  of  air  is  proportional 
to  the  force  evolved  and  absorbed  in  those  operations."  In  1842,  Mayer 
announced  that  he  had  by  agitating  water  raised  its  temperature  from 
12°  C.  to  13°  C,  without  however  indicating  the  force  employed;  and, 
about  the  same  date,  and  founding  largely  on  physiological  considerations 
regarding  animal  heat  and  the  heat  of  the  blood,  Mayer  attempted  to 
calculate  the  mechanical  equivalent  of  heat.  This  important  determin- 
ation was  finall}"  experimentall)'  made  by  Joule  in  1845  and  1847,  when 
he  employed  a  paddle-wheel  to  produce  fluid  friction,  and  obtained  the 
equivalent  from  the  agitation  of  water,  sperm  oil,  and  mercury.  (See 
Joule's  Scientific  Papers,  vol.  I.,  p.  298). 

Heat  then  being  a  kind  of  energy,  it  can  be  measured  in  terms  of  the 
unit  of  energy,  as,  for  example,  by  the  foot  pound,  the  centimetre- 
gramme  or  erg,  or  it  may  be  expressed  in  thermal  units.  The  thermal 
unit  is  the  quantity  of  heat  required  to  raise  the  temperature  of  unit 
mass  of  water  unit  degree  betAveen  the  limits  of  0°  C.  and  40°  C.  Thus 
the  British  thermal  unit  is  the  "pound-degree,"  that  is  the  heat  required 
to  raise  a  pound  avoirdupois  of  water  from  60°  F.  to  61°  F.,  and  the 
French  thermal  unit  is  the  "  calorie  "  or  kilogramme-degree,  the  heat 
required  to  raise  a  kilogramme  of  Avater  from  15°  C.  to  16°  C,  This 
statement  enables  one  to  understand  what  is  meant  by  the  dynamical 
equivalent  of  heat,  or  the  value  in  terms  of  a  unit  of  Avork  of  a  unit  of 
heat.  Joule  found  by  experiment,  as  already  indicated,  that  772"55 
foot-pounds  of  work  are  required  to  raise  1  pound  of  Avater  from  60°  F.  to 
61°  F.,  the  intensity  of  gravity  being  that  of  the  sea-level  at  GreenAvich, 
or  1389-26  foot-pounds  are  required  to  Avarm  1  pound  of  AA^ater  from 
0°  C.  to  1°  C.  Reduce  1389-26  feet  to  metres  and  Ave  have  423-437 
metres.  The  AA'ork  done  therefore  is  eqvuA^alent  to  (approximately)  424 
kilogrammetres,  if  the  unit  of  heat  be  the  calorie  aboA^e  defined.  To 
couA^ert  kilogrammetres  into  calories  diAade  by  424,  and  to  convert 
calories  into  kilogrammetres  multiply  by  424.  The  dynamical  equiA'alent, 
or  Joule,  denoted  by  J,  may  be  stated  thus:  The  same  energy  AA'hich 
elevates  424  kilogrammes  1  metre  high  Avill,  as  heat,  raise  1  kilogramme 
of  Avater  1°  C,  or  a  Aveight  of  424  kilogrammes,  if  alloAved  to  fall  from  a 
height  of  1  metre,  Avould,  by  its  concussion,  produce  as  much  heat  as 
Avould  raise  the  temperatiu-e  of  1  kilogramme  of  Avater  1"  C  Difficulty 
of  experimentation  has  hitherto  prevented  the  accurate  determination  of 


MATTER  AND  ENERGY.  13 

the  mecliamcal  equivalent  of  light,  electricity,  or  magnetism;  but  there 
is  sufficient  evidence  that  these  also  are  modes  of  energy,  and  that  they 
may  be  therefore  transformed  or  transmuted,  just  as  the  energy  of 
molar  motion  can  become  the  energy  of  molecular  motion  or  heat. 

Consult  Von  Helmholtz'  Lectures  on  Scientific  Subjects,  No.  7  ;  Prof.  P.  G. 
Tait's  Properties  of  Matter;  Prof.  Tait's  Recent  Advances  in  Physical  Science; 
Joule's  Scientific  Papers ;  Grove — The  Correlation  of  Physical  Forces ;  also, 
Address  on  Continuity. 


Chap.  III.— GENERAL  PRINCIPLES  OF  BIOLOGY. 

Before  entering  upon  the  study  of  the  functions  of  a  specific  organism, 
it  will  be  instructive  to  consider  some  of  the  general  characteristics  of 
living  things,  and  to  endeavour  to  grasp  some  of  the  conditions — 
chemical,  'physical,  and  vital — which  govern  the  origin,  development, 
life-history,  and  death  of  all  living  beings.  This  preliminary  discus- 
sion of  the  General  Principles  of  Biology  prepares  the  way  for  the 
more  detailed  treatment  of  the  Physiology  of  Man.  The  leading- 
characteristics  of  living  beings  or  of  living  matter  may  be  considered 
under  the  follo"vving  heads  : — 

1.  Physical  Structure. — Solid  and  fluid  matters  invariably  co-exist 
in  living  bodies  :  the  solids  contain  fluids  in  their  cavities  or  interspaces. 
No  living  matter  ever  assumes  a  crj^stalline  form,  but  crystals  may  be 
embedded  in  it.  The  colloidal  state,  in  which  matter  is  soft,  diffluent, 
and  readily  permeated  by  water,  oxygen,  and  the  crystalloids,  is  so 
characteristic  of  living  stuff  that  Graham,  its  first  investigator,  termed 
it  the  dynamical  state  of  matter.  The  colloidal  condition,  however, 
is  not  peculiar  to  living  stuff,  inasmuch  as  silicic  acid  and  peroxide  of 
iron  may  assume  this  state.  All  the  solid  parts  of  living  matter  are 
more  or  less  moist;  many  have  the  character  of  softness,  and  they 
readily  absorb  water,  becoming  swollen  by  imbibition.  When  water 
is  absorbed  by  starch  there  is  an  evolution  of  heat.  This  property 
of  swelling  up  by  absorption  of  water  has  led  to  the  conception  that 
the  molecular  structure  of  such  substances  as  the  walls  of  cells,  and 
starch  grains,  may  consist  of  very  minute  solid  particles  (micellce  of 
Nsegeli),  each  particle  being  surrounded  by  a  layer  of  fluid.  Accord- 
ing to  this  view,  in  a  perfectly  dry  organic  substance  the  micellae 
would  be  in  contact  on  all  sides,  and  when  it  absorbed  water  the 
water  would  penetrate  between  the  micellae,  forcing  them  asunder 
against  the  opposing  action  of  cohesion.  Another  view  is  that  of 
Strasburger,  which  appears  to  explain  the  phenomena  of  imbibition 
more   satisfactorily.      Rejecting   the   micellar    theory   of    ISTsegeli,    he 


14  INTRODUCTION. 

supposes  that  "  the  force  which  l)iucls  together  the  molecules  is  of  a 
chemical  as  opposed  to  a  physical  nature ;  that  they  are  held  together 
not  by  cohesion,  but  by  chemical  affinity  :  he  regards  them  as  being 
linked  together,  probably  by  means  of  multivalent  atoms,  into  mole- 
cular networks,  the  water  present  being  retained  in  the  meshes  by 
intermolecular  capillarity/'  (Vines'  Plujaiologij  of  Plants,  p.  33.) 
This  theory  assumes  that  living  colloidal  matter  consists  of  a  dis- 
tensible molecular  network,  capable  of  absorbing  water  until  the 
capillary  attraction  is  greater  than  the  chemical  affinity  by  which  the 
molecules  are  bound  together,  and  when  this  limit  is  passed  the 
molecular  structure  is  desti'oyed.  In  the  case  of  protoplasm,  ^  it  may 
be  supposed  that  the  molecules  are  in  a  state  of  incessant  change,  and 
that  the  absorption  and  the  liberation  of  water  i)lay  an  important  part 
in  vital  phenomena. 

2.  Chemical  Composition — Of  the  sixty-five  or  sixty-eight 
elements,  not  more  than  eighteen  or  twenty  have  been  found  in  living 
things.  Chief  among  these  are  oxygen,  hydrogen,  nitrogen,  and  cai'bon. 
It  is  interesting  to  note  that  the  first  three  can  only  jDass  into  the  solid 
state  imder  enormous  pressures  and  at  a  low  temperature,  an  indication 
of  their  great  molecular  mobility.  Oxygen  enters  into  combination 
with  hydrogen,  carbon,  and  even  with  nitrogen,  an  element  remark- 
able for  its  chemical  indifference.  Hydrogen  and  carbon  are  chemically 
indifferent  to  other  substances  at  ordinary  temperatures.  Carbon  is 
allotropic,  appearing  in  the  unlike  forms  of  charcoal,  graphite,  and 
the  diamond.  Along  Avith  these  there  are  associated,  of  the  non- 
metals— sidphur,  phosphorus,  and  chlorine ;  of  the  alkalies — sodium 
and  potassium;  of  the  alkaline  earths — calcium  and  magnesium ;  and 
of  the  metals — iron.  In  addition,  there  are  minute  quantities  of 
silicon  and  fluorine,  and  there  may  be  iodine,  bromine,  manganese, 
aluminium,  copper,  and  lead  in  the  tissues  of  particular  plants  and 
animals.  It  is  interesting  to  notice  that  if  we  take  the  classification 
of  the  elements  generally  accepted  by  chemists  we  find  that  organic 
matter  is  built  up  of  representatives  of  the  hydrogen  group — hydrogen 
(1),  chlorine  (35-37),  and  bromine  (79"75);  of  the  iodine  group — iodine 
(126"53)  and  fluorine  (19);  of  the  oxygen  group — oxygen  (15'96), 
sulphur  (31-98);  of  the  nitrogen  group — nitrogen  (14-01),  phosjihorus 
(30-96);  of  the  carbon  group — carbon  (11-9.7),  silicon  (28);  of  the 
sodium  group  of  metals — sodium  (22-99),  potassium  (39*04);  of  the 
calcium  group  of  metals,  calcium  (39-9);  of  the  magnesium  group  of 

^  Protoplasm,  irp^ros,  first,  -rfKaap-a,  anything  formed.  A  term  first  used  by 
Von  Mohl  to  describe  the  mucilaginous  granular  contents  of  the  vegetable  cell ; 
now  applied  to  the  simplest  form  of  matter  constituting  the  physical  basis  of  life. 


GENERAL  PRINCIPLES  OF  BIOLOGY.  15 

metals,  magnesium  (23 '94);  and  of  the  iron  group  of  metals,  iron 
(55 "9) — all  the  other  groups  being  unrepresented.  Excluding  the 
metals  of  the  alkaKes  and  alkaline  earths,  iron  is  the  only  metal 
essentia]  to  some  of  the  higher  forms  of  living  animal  matter.  Of  the 
fifteen  non-metals,  nine  are  represented,  whilst  of  the  fifty-three  metals 
we  find  only  five  representatives,  excluding  those  of  rare  and  probably 
of  accidental  occurrence.  Further,  if  we  consider  that  the  earth's  solid 
crust  consists  chiefly  of  oxygen,  silicon,  aluminium,  iron,  calcium, 
magnesium,  sodium,  and  potassium,  and  that  water  consists  of  oxygen 
and  hydrogen,  we  see  that  carbon  and  nitrogen  in  particular  are 
characteristic  of  living  matter,  and  it  may  further  be  stated  that  no 
living  matter  can  exist  ^vithout  the  presence  of  the  four,  oxygen, 
hydrogen,  carbon,  and  nitrogen.  Their  compounds  form,  from  the 
chemical  point  of  view,  the  basis  of  life. 

The  elements  are  so  combined  in  li^'ing  matter  as  to  constitute  com- 
pound bodies  which  may  be  separated  as  such  by  chemical  processes. 
Such  compounds  are  termed  i^roximate  principles.  For  example,  phos- 
phate of  lime  is  a  proximate  constituent  of  bone,  but  phosphoric  acid 
and  oxide  of  calcium  are  not  proximate  constituents  ;  in  bone  they  do 
not  exist  individually,  but  united  to  form  the  salt,  phosphate  of  lime. 
Chief  among  proximate  substances  is  water,  which  as  a  rule  forms  more 
than  three-fourths  of  the  weight  of  a  living  body.  An  organism  may, 
however,  contain  almost  no  water  and  still  have  the  potentiality  of 
life,  as  has  been  shown  in  the  case  of  dried  seeds  and  of  dried  rotifers 
and  infusoria.  In  the  process  of  freezing,  also,  water  may  separate 
from  the  organic  stufi"  and  become  ice,  and  yet  on  careful  thawing  it 
may  be  taken  up  again,  and  the  structure  may  return  to  its  former 
condition.  In  these  instances,  the  molecular  changes  on  which  life 
depends,  and  for  the  play  of  which  the  presence  of  water  is  necessary, 
have  been  arrested,  and  it  is  only  on  the  return  of  water  that  life  is 
renewed. 

Certain  proximate  principles  are  the  same  as  those  met  "\\-ith  in  the 
crust  of  the  earth  or  in  the  water  of  oceans  and  rivers,  such  as  chlorides 
of  sodium  and  potassium,  sulphates  of  soda  and  potash,  phosphates  of 
soda,  potash,  lime,  and  magnesia,  and  fluoride  of  calcium.  The  proxi- 
mate substances  more  characteristic  of  the  tissues  of  plants  and  of 
animals  are  compounds  formed  of  carbon,  hydrogen,  and  oxygen, 
such  as  starches,  sugars,  fats  ;  or  formed  of  carbon,  hydrogen,  oxygen, 
nitrogen,  and  sulphur  or  phosphorus,  such  as  albumin,  glutin,  or  lecithin. 
Compounds  formed  of  three  elements  have,  especially  in  the  dry  con- 
dition, a  considerable  amount  of  chemical  stability.  Thus  dry  starch 
will  not  readily  decompose.      On   the   other   hand,    compounds   con- 


16  INTRODUCTION. 

taining  four  or  more  elements  arc  much  less  stable.  They  tend 
easily  to  disintegration.  They  exist  only  within  a  limited  range  of 
temperature  and  pressure,  and  under  the  action  of  bodies  in  a  more 
active  molecular  state  (ferments)  the  complex  organic  molecule 
falls  to  pieces,  not  usually  resolving  itself  into  its  elements,  but  into 
simpler  groups  of  elements.  Thus  a  molecule  of  albumin  may  split  up 
into  simpler  molecules  of  leucin,  tyrosin,  and  other  less  complex  bodies, 
such  as  Avater  and  urea.  This  molecular  instability,  probably,  is  one  of 
the  conditions  of  vitality,  and  as  it  is  always  most  highly  manifested 
by  the  compounds  containing  nitrogen,  it  has  been  conjectured  that  it 
may  be  due  to  the  Aveak  affinities  of  nitrogen-molecules  for  the  other 
simpler  molecules  existing  in  organic  matter.  For  example,  two  well- 
known  explosives  are  gun  cotton  and  nitroglycerine.  Gun  cotton  is 
cellulose,  CgH^oOg,  in  which  3  atoms  of  hydrogen  are  replaced  by  3 
atoms  of  a  stable  nitrogen  compound,  NOg — thus  :  CgH7(N02)305. 
Again,  nitroglycerine  is  glycerine,  CgHgOg,  in  which  3  atoms  of 
hydrogen  are  replaced  by  3  atoms  of  the  same  compound,  NOg,  thus  : 
C3H5(N02)303.  Another  example  is  picric  acid  :  first  one  atom 
of  hydrogen  in  benzol,  C^Hg,  is  replaced  by  an  atom  of  hydroxyl, 
HO,  thus  :  CgHj.HO,  or  phenol ;  then  3  atoms  of  the  hydrogen  in 
phenol  are  replaced  by  3  atoms  of  NOg,  forming  picric  acid,  thus  : 
C6H2(N02)3HO.  These  compounds,  especially  the  former  two,  are  re- 
markable for  chemical  instability,  and  they  offer  an  analogy  to  the 
constitution  of  living  stuff.  A  sudden  change  of  temperature,  a  vibra- 
tion, a  concussion,  may  cause  the  molecule  to  fly  to  jDieces,  and  the 
fragments  are  of  course  simpler  in  structure.  We  shall  see  that  all 
vital  actions  are  characterized  and  accompanied  by  the  appearance  of 
chemical  substances  much  simpler  in  composition  than  the  substance 
which  was  the  seat  of  these  actions. 

A  living  body  is  continually  undergoing  a  series  of  chemical  changes 
of  composition  and  decomposition,  as  a  result  of  which  there  is  an 
incessant  renovation  of  the  molecules  of  the  organism.  Chemical 
changes  are  a  necessary  condition  of  the  action  of  living  matter,  or  it 
may  be  said  that  the  living  state  is  always  associated  with  chemical 
change;  part  of  the  living  matter  dies,  is  decomposed,  or  rather  its 
decomposition  is  its  death,  and  the  dead  matter  is  then  thrown  out  of 
the  organism.  New  matter  is  added  from  without,  and  thus  there  is  a 
perpetual  exchange  between  the  organic  and  the  inorganic  worlds,  which 
may  be  termed  the  ciradation  of  niatter. 

3.  Organic  Form  and  Mode  of  Gro\vth.  Li^dng  bodies  are 
organized,  that  is,  they  are  composed  of  dissimilar  or  distinct  parts 
arranged  in  a  certain  order,  and  each  j^art  performs  a  determinate  office 


GENERAL  PRINCIPLES  OF  BIOLOGY. 


17 


or  function  in  connection  with  the  maintenance  of  the  life  of  the  whole. 
There  is  reason  to  believe  that  this  is  true  even  of  the  apparently  simple 
structure  of  an  amoeba,  as  new  modes  of  investigation  reveal  details  of 
structure  which  no  doubt  have  a  special  physiological  significance.  The 
external  form  of  living  beings  is  consistent  with  a  certain  morphological 
type.  At  the  beginning  of  existence  the  typical  form  is  nearly  spherical ; 
afterwards,  in  the  process  of  growth,  a  form  is  developed  peculiar  to  the 
sjjecies.  The  spherical  form  is  not  only 
characteristic  of  the  organism  at  the  com- 
mencement of  life — the  egg  or  ovum,  Fig. 
10 — but  is  seen  also  in  the  primitive 
elements  which  compose  the  developed 
organism.  (See  cells.)  Organized  matter 
may  be  composed  of  molecules,  granules, 
cells,  fibres,  membranes,  and  tubes. 

The  mode  in  which  new  particles  of 
matter  enter  a  living  organism  furnishes 
also  a  distinctive  character.  A  crystal 
grows  by  new  moleciiles  of  similar  composition  to  itself  being  applied 
directly  to  its  surface,  whilst  a  living  thing  absorbs  the  dead  matter  intO' 
its  own  substance  and  converts  what  was  previously  dead  into  living 
matter  like  itself.  In  other  words,  dead  bodies  increase  in  size  by 
apposition,  living  bodies  grow  by  metabolism^  and  intussusception. ^ 

The  manner  in  which  the  growth  of  crystalline  forms  may  be  modified 
by  various  physical  conditions  so  as  even  to  simulate  organic  forms  has 
been  the  subject  of  various  exhaustive  inquiries,  which  have  thrown 
light  on  the  mode  of  origin  of  concretions,  on  the  formation  of  shell,  and 
on  the  deposition  of  earthy  matter  in  soft  tissues.  In  1857,  George 
Rainey  showed  that  certain  crystalline  matters,  when  deposited  in  viscous 
or  gummy  solutions,  assume  globular  and  cell-like  forms.  ^  His  method 
consisted  in  saturating  a  solution  of  gum  arable  with  carbonate  of  potash 
(specific  gravity  1-4068),  placing  the  fluid  in  a  small  wide-mouthed 
l)ottle,  so  as  to  fill  it  half  full,  and  introducing  into  the  bottle  two  clean 


Fig.  10.     Ovum  from  an  Echiuoderm 


^  Metabolism,  from  fiera^oXt],  change ;  the  power  living  matter  possesses  of 
changing  other  matters  brought  under  its  influence.     First  used  by  Schwann. 

^ Intiissusception.  Intus,  within;  suscipio,  I  receive.  The  absorption  of 
matters  into  the  substance  of  living  material. 

^  On  the  Mode  of  Formation  of  Shells  of  Animals,  of  Bone,  and  of  several  other 
Structures  by  a  Process  of  Molecular  Coalescence.  By  Geo.  Rainey,  M.R.C.S. 
Lond.,  1858.  See  also  Quart.  Jour,  of  Micros.  Science,  1858,  and  On  the  Influence, 
of  Colloids  on  Crystalline  Form  and  Cohesion,  by  William  Miller  Ord,  M.D.,  etc. 
Lond.,  1879. 

I.  B 


18  INTRODUCTION. 

slides  of  glass,  leaning  against  each  other  at  the  top.  The  upper  part  of 
the  bottle  was  then  filled  by  gently  pouring  in  a  solution  of  gum  arabic 
in  water,  of  a  specific  gravity  of  r0844:,  and  the  mouth  of  the  bottle  was 
covered  with  a  sheet  of  paper.  The  whole  was  laid  aside  for  a  period  of 
three  weeks  or  a  month.  The  slides  Avere  then  removed  and  were 
found  to  be  coated  with  a  deposit  of  carbonate  of  lime.  The  carbonate, 
however,  instead  of  being  deposited  in  a  crystalline  form  was  in  the 
condition  of  fine  molecules,  and  by  examining  such  slides  at  various 
intervals  it  was  shown  that  these  molecules  coalesce  so  as  to  form  spheres, 
which  in  turn  may  coalesce  to  form  larger  ones.  The  perfect  spheres 
exhibit  both  radial  and  concentric  markings,  and  in  polarized  light  show 
.a  well  marked  cross.     (See  Figs.  11  and  12.)     The  presence  of  the 

Fig.  11.— Precipitation  of  Carbonate  of  Lime,  showing  the  crystalline 
form  passing  into  globular  forms,  (a)  Crystalline  form ;  (6)  angles  of 
crystals  rounded  off ;  (c)  ovoid  forms ;  (d)  coalescence  of  ovoid  forms. 


^.=.o=^ov=fe(7_p  oo  g,  ^d 


"s 


m%mm 


j;y.   -oce    4'cb  "^ 


QMi 


Fig.  12.— Precipitation  of  Carbonate  of  Lime  from  a  Viscous  Solution  on 
a  slide  of  glass,  showing  (beginning  on  the  left  hand)  (a)  finely  mole- 
cular forms,  then  globular  forms  (6) ;  and  these  forming  larger  and 
larger  bodies  by  molecular  coalescence  (c,  rf.)  On  the  right  hand,  large 
bodies  showing  concentric  circles  and  radiating  lines  (/). 

colloidal  gum,  according  to  Eainey,  "  annuls  the  polarity  of  the  crystal, 
and  allows  the  molecules  of  the  crystal  to  obey  simple  laws  of  common 
and  mutual  attraction."  This  aggregating  of  the  molecules  he  terms 
"  molecular  coalescence."     His  words  are  : 

"When  the  molecules  of  pure  carbonate  of  lime,  that  is  carbonate  of  lime 
uncombined  with  a  viscid  substance,  come  into  existence  they  immediately 
commence  arranging  themselves  in  straight  lines,  and  thus  when  collected  together 
form  rectilineal  figures  or  crystals  ;  but  when  the  impure  carbonate,  that  is  car- 
bonate combined  with  a  viscid  substance,  comes  into  existence,  under  similar  cir- 
cumstances, its  molecules  assume  a  curvilinear  disposition,  and  hence  become 
collected  into  globules."     (Eainey,  op.  cit.  p.  31.) 

Further,  if  the  spheres  thus  formed  are  plunged  into  solutions  of  gum 
of  difierent  specific  gravity,  the  spheres  break  up  along  the  radial  lines 
and  crumble  into  molecules.  This  is  "molecular  disintegration." 
Eainey  showed  that  in  the  soft  parts  under  the  shell  of  the  young 


GENERAL  PRINCIPLES  OF  BIOLOGY.  19 

lobster,  crab,  or  shrimp,  bodies  exactly  like  thosg  thus  artificially  pro- 
duced may  be  found.  I  possess  a  number  of  Rainey's  original  prepara- 
tions, and  after  the  lapse  of  thirty  years  they  show  all  the  gradations  of 
form  depicted  in  Figs.  11  and  12. 

Professor  Harting,  of  Utrecht,  investigated  this  matter  independently 
of,  and  even  prior  to,  the  appearance  of  Rainey's  papers.  He  obtained 
similar  results  by  allowing  carbonate  of  lime  to  separate  out  of  an 
albuminous  or  colloid  fluid. 

"  He  states  that  the  albumin  contained  in  the  calcosphcerites  [globular  bodies  of 
Eainey]  undergoes  a  chemical  change  bringing  it  near  to  chitin,  and  says  that  the 
same  is  effected  in  albumin  by  chloride  of  calcium.  To  this  moditication  he  gives 
the  name  calcoglobulin.  He  finds  in  his  experiments  explanations  of  the  structure 
of  the  shells  of  Lamellibranchiata  and  some  Gasteropoda,  of  the  calcareous  plates 
of  the  bones  of  Sepia,  of  the  shells  of  Foraminifera  and  loculi  of  Bryozoa,  the 
spicules  and  sclerites  of  Alcyonaria  ;  and  states  that  the  last  mentioned  forms  are 
produced  when  cartilage,  previously  impregnated  with  calcium  chloride,  is  placed 
in  a  solution  of  potassium  carbonate  mixed  with  a  little  sodium  phosphate. "  (Ord, 
op.  cit.  p.  7.) 

Dr.  Ord  has  modified  Rainey's  method  with  important  results  bearing 
on  the  formation  of  bone  and  especially  on  the  crystalline  forms  assumed 
by  various  urinary  sediments. 

Another  striking  example  of  the  production  of  organic-like  forms  from 
dead  matter  is  the  formation  of  processes  from  myelin  or  protagon  by  the 
action  of  water. ^  Beat  up  the  yolk  of  an  egg  in  30  cc.  of  absolute 
alcohol,  boil  for  one  or  two  minutes,  and  then  filter  on  a  flat  plate.  In 
the  small  amount  of  filtrate  obtained  a  gelatinous  yellow  stuff  appears. 
This  is  impure  protagon  or  myelin.  Allow  the  alcohol  to  evaporate. 
Place  a  small  portion  of  protagon 
on  a  slide,  lay  a  cover-glass  gently 
over  it,  place  it  on  the  stage  of  the 
microscope,  and  focus  so  as  to  see  the 
edge  of  the  mass.  This  will  be  seen 
to  be  amorphous.  Then  allow  a 
drop  of  water  to  pass  below  the 
cover-glass  and  immediately  beauti- 
ful snake-like  forms  will  shoot  out, 
bend,  curl,  and   assume   grotesque 

.  -  .       -rr       t  -FiG-   13.— Protagon  or  myelin  forms, 

lOrmS    such   as    are    seen   m   Xlg.   13.  curved  and   spiral.      Processes  shoot- 

-Kir      ,  1  1,1,1  ,  •  in?  out  from  a  mass  of  protagon  on 

Montgomery  showed  that  by  acting  addition  of  water. 

on  protagon  with  water,  albumin,  or  glycerine,  forms  may  be  ob- 
tained simulating  organic  fibres,  varicose  nerve  fibres,  the  broken  down 
matter  of  the  spinal  cord  or  brain,  and  even  cell-like  bodies. 

^  Montgomery,  On  the  Formation  of  so-called  Cells.     Lond.,  1867. 


20  INTRODUCTION. 

All  of  these  observations  indicate  that  forms  similar  to  those  pro- 
duced in  and  liy  living  matter  may  be  artificially  produced  in  dead 
matter,  and  that  molecular  processes  of  coalescence,  disintegration,  and 
imbibition,  may  play  an  important  part  in  the  formation  of  shell,  in  the 
development  of  the  curious  spicules  of  sponges  and  synaptidae,  in  the 
deposition  of  calcareous  matter  in  tendon,  in  the  walls  of  vessels,  and  in 
fibrous  membranes  (phenomena  familiar  to  the  pathologist),  in  the 
formation  of  the  hard  tissues  of  teeth,  and  in  the  calcification  of  cartilage, 
one  of  the  early  stages  of  ossification. 

4.  Dynamical  Characters. — We  have  already  seen  that  the  various 
forms  of  physical  activit}-,  heat,  light,  electricity,  motion,  chemical 
affinity,  are  all  related  and  convertible  so  that  they  are  now  regarded 
as  but  various  modes  of  one  energy,  potential  or  kinetic.  But  plants 
and  animals  exhibit  activities  peculiar  to  themselves,  such  as  those  of 
assimilation  and  growth,  irritability,  contractility,  reproduction,  and 
nervous  actions,  which  are  all  manifestations  of  energy.  Is  this 
the  same  energy  as  is  active  in  the  world  of  dead  matter,  or  have 
li^ang  things  an  energj'  of  their  own  1  This  is  a  question  of  pro- 
found importance.  The  older  physiologists  thought  that  the  energy 
of  living  things  Avas  an  entity  or  principle  derived  from  the  germ,  and 
quite  different  in  kind  from  the  various  forces  of  the  outer  world. 
This  energy  was  described  under  such  terms  as  vital  force,  life, 
the  vital  principle,  and  it  was  supposed  to  exert  power  not  onlj^  over 
the  matter  introduced  into  the  body,  but  also  over  the  outer  forces 
acting  on  the  body.  Further,  instead  of  this  \dtal  force  being  correlated 
to  the  outer  forces,  it  was  supposed  to  be  in  some  way  opposed  to  them, 
so  that  when  the  vital  force  ceased  to  act,  the  natural  forces  came  into 
play  and  acted  on  the  body  as  if  it  were  composed  of  dead  matter.  Such 
views  were  generally  held  until  1845,  Avhen  Mayer  first  broke  ground  by 
setting  forth  that  all  change  in  the  living  organism,  animal  or  vegetable, 
"  lies  in  the  forces  acting  on  it  from  ^Wthout."  There  can  be  no 
cjuestion  that  Mayer  first  directed  the  attention  of  physiologists  to 
this  aspect  of  the  subject,  and  that  it  was  largely  from  physiological 
considerations  that  he  was  led  to  his  speculations  regarding  the 
physical  forces.  In  1850,  Dr.  W.  B.  Carpenter  applied  to  the  explana- 
tion of  physiological  phenomena  the  doctrine  of  the  correlation  of  the 
physical  forces,  and  showed  that  the  vital  forces  were  generated  in 
li^dng  bodies  by  the  transformation  of  light,  heat,  and  chemical 
action,  and  that  the  energy  thus  derived  from  the  outer  world  was 
given  back  to  it  again  as  heat  and  motion,  and  to  a  less  degree  in 
most  animals  as  electricity  and  light.  In  1859,  these  views  were 
supported   and   extended   in   a  modified    form   by   Professor  Joseph 


GENERAL  PRINCIPLES  OF  BIOLOGY.  21 

Le  Conte,  who  argued  that  the  chemical  forces,  set  free  in  the  plant 
and  animal,  were  transformed  into  vital  force,  and  that  by  this  action 
matter  was  raised  from  the  plane  of  dead  matter  to  the  higher  plane 
of  living  matter.  Both  of  these  vsriters,  however,  laid  special  stress 
on  the  view  that  the  medium  of  this  transformation  of  physical  into 
vital  force  was  organized  or  living  matter.  This  is  clearly  shown  in 
the  words  of  Dr.  Carpenter : 

"It  is  the  speciality  of  the  material  substratum  thus  furnishing  the  medium  or 
instrument  of  the  metamorphosis  which  establishes,  and  must  ever  maintain,  a 
well-marked  boundary  line  between  physical  and  vital  forces.  Starting  from  the 
abstract  notion  of  force  as  emanating  at  once  from  the  Divine  Will,  we  might  say 
that  this  force,  operating  through  inorganic  matter,  manifests  itself  as  electricity, 
magnetism,  light,  heat,  chemical  aflinity,  and  mechanical  motion ;  but  that  when 
directed  through  organized  structures  it  aflfects  the  operations  of  growth,  develop- 
ment, and  chemico-vital  transformations  and  the  like,  and  is  further  meta- 
morphosed, through  the  instrumentality  of  the  structures  thus  generated,  into 
nervous  agency  and  muscular  power."  (Carpenter,  Trans,  of  Royal  Society, 
1850,  p.  752.) 

A  careful  study  of  the  properties  of  protoplasm,  more  especially  in 
the  vegetable  cell,  and  of  the  action  on  it  of  physical  forces,  such 
as  those  of  heat  and  light,  and  the  influence  of  the  teaching  of 
Herbert  Spencer  in  his  Principles  of  Biology,  have  led  to  the  general 
adoption  of  these  views;  and  the  principle  of  the  conservation  of  energy, 
as  affecting  the  interactions  of  the  forces  manifested  by  dead  and  living- 
matter,  is  now,  to  the  physiological  inquirer,  what  it  is,  in  the  language 
of  Clerk  Maxwell,  "  to  the  physical  inquirer,  a  principle  on  which  he 
may  hang  every  known  law  relating  to  physical  actions,  and  by  which 
he  may  be  put  in  the  way  to  discover  the  relations  of  such  actions  in 
new  branches  of  science."     (Clerk  Maxwell,  Matter  a7ul  Motion,  p.  60.) 

Let  us  now  discuss  how  these  principles  apply  to  the  phenomena 
of  plant  and  animal  life. 

Plants  containing  chlorophyll  require  comparatively  simple  chemical 
substances  as  food.  All  plants  absorb  oxygen  from  the  air,  and  all 
green  plants,  under  the  influence  of  sunlight,  absorb  carbonic  acid. 
This  carbonic  acid  is  decomposed,  the  carbon  being  retained  in  the 
cell,  whilst  oxygen  is  liberated.  Further,  nitrogen  exists  in  the 
juices  of  plants,  but  there  is  no  evidence  that  it  is  directly  used  by 
the  living  matter.  Plants  may  also  absorb  a  small  amount  of  ammonia 
from  the  air,  and  they  obtain  water  chiefly  from  the  soil.  The  roots 
obtain  from  the  soil,  or  from  the  water  in  which  the  plant  grows, 
ammonia  and  its  salts  (the  nitrate,  sulphate,  and  phosphate),  nitrates 
of   soda,  potash,  lime,   and   magnesia,   chlorides   of   the   alkalies   and 


22  INTRODUCTION. 

alkaline  earths,  sul])hates  of  potash  and  lime,  phosi)hates  of  soda, 
potash,  ammonia,  lime,  and  magnesia,  and  iron  in  the  form  of  a 
salt.  From  the  substances  thus  derived  from  the  air  and  the  soil, 
the  plant  obtains  the  elements  necessary  for  its  existence,  namely, 
carbon,  hydrogen,  oxygen,  nitrogen,  sulphur,  phosphorus,  })otassium, 
calcium,  magnesium,  and  iron,  and  in  some  plants,  chlorine.  The 
first  four — carbon,  hydrogen,  oxygen,  and  nitrogen — are  absolutely 
necessary  for  those  metabolic  processes  on  which  the  life  of  the  plant 
depends,  whilst  the  others  apparently  assist  in  the  performance  of 
these  processes.  In  addition,  plants  may  contain  silica.  The 
carbon  is  obtained  by  plants  containing  chlorophyll  by  the  decom- 
position of  carbonic  acid  under  the  influence  of  light,  but  plants 
destitute  of  chlorophj'll  (fungi)  cannot  thus  decompose  carbonic 
acid,  and  they  obtain  the  requisite  carbon  from  organic  matter 
in  which  carbon  is  united  to  hydrogen.  Hydrogen  is  obtained 
from  water,  oxygen  from  the  air,  and  nitrogen  from  ammonia  and  its 
salts  by  plants  of  lower  organization,  and  from  nitrates  by  plants  of 
a  higher  kind.  The  sulphur  necessary  for  building  up  proteid  matter 
is  yielded  by  sulphates ;  the  phosphorus  which  exists  in  chlorophyll 
and  protoplasm,  by  phosphates ;  and  the  bases,  potassium,  calcium, 
and  magnesium,  by  various  salts.  Although  iron  does  not  exist  in 
chlorophyll,  it  appears  to  be  necessary  for  its  formation.  From  these 
simple  materials,  the  protoplasm  of  the  plant  builds  up  more  complex 
bodies,  some  non-nitrogenous  and  others  nitrogenous.  This  process 
of  building  up  may  go  along  with  the  reverse  process  of  pulling 
down;  or,  in  other  words,  synthetic  and  analytic  changes  may  go  on, 
even  simultaneously.  The  new  matter  supplied  by  the  food  may  be, 
by  these  processes  of  constructive  or  destructive  metabolism,  divided 
into  three  portions — one  part  by  constructive  metabolism  is  used 
for  building  up  the  tissues  of  the  plant  (growth);  a  second  portion, 
also  by  constructive  metabolism,  is  built  up  into  certain  bodies  which 
are  stored  \\\)  in  the  tissues  of  the  plant,  constituting  reserve  material; 
whilst  the  third  portion,  by  a  process  of  destructive  metabolism,  may 
be  decomposed  in  the  tissues  of  the  plant,  never  entering  into  the 
composition  of  these  tissues,  and  the  products  of  decomposition  are 
excreted  as  useless.  In  plants,  synthetic  are  carried  on  to  a  much 
greater  extent  than  analytic  processes ;  synthesis  indeed  is  characteristic 
of  the  lives  of  all  plants  containing  chlorophyll. 

By  such  processes  the  plant  builds  up  either  non-nitrogenous  or 
nitrogenous  substances.  The  formation  of  non-nitrogenous  organic 
substances,  such  as  starch,  is  known  to  be  directly  connected  with 
the   action   of   chlorophyll,    imder   the   stimulus  of   light.      In  green 


GENERAL  PRINCIPLES  OF  BIOLOGY.  23 

vegetable  cells,  the  protoplasm  contains  small  corpuscles,  the  chloro- 
phyll corpuscles,  and  it  has  been  shown  that  these  consist  of  a  kind 
of  matrix  permeated  by  the  chlorophyll,  probably  dissolved  in  an  oil. 
The  green  matter  of  chlorophyll,  called  by  Hoppe-Seyler  chlorophyllan, 
has  a  formula  of  Cj9H22N203(P  1),  and  is  believed  to  be  a  lecithin  com- 
pound containing  phosphorus.  It  is  important  to  note  that  it  is  a 
highly  complex  body,  formed  originally  from  the  protoplasm  of  the 
cell.  Vegetable  cells  containing  chlorophyll,  under  the  influence  of 
sunlight,  as  already  said,  decompose  carbonic  acid  and  liberate  oxygen. 
This  process  is  not  to  be  confounded  with  the  respiration  of  the  pro- 
toplasm of  the  cell,  which  consists  in  the  absorption  of  oxygen  and 
the  liberation  of  carbonic  acid ;  but  is  the  first  step  in  the  constructive 
metabolism  by  which  the  chlorophyll  builds  up  starch.  Without 
light  no  starch  is  formed,  nor,  on  the  other  hand,  can  it  be  formed 
without  carbonic  acid,  even  when  the  chlorophyll  is  exposed  to  light. 
The  rapidity  of  the  process  in  certain  plants  is  very  remarkable. 
Thus  "  Kraus  found  that  starch  grains  made  their  appearance  in  the 
chlorophyll  corpuscles  of  Spyrogyra  within  five  minutes  after  exposure 
to  bright  sunlight,  within  two  hours  in  diffuse  daylight;  in  Funaria 
thej^  made  their  appearance  after  two  hours'  exposure  to  sunlight, 
and  after  six  hours'  exposure  to  diffuse  daylight."  (Vines,  Physiology 
of  Plants,  p.  147.) 

It  is  probable  that  chlorophyll-corpuscles  form  starch  by  the  union 
of  carbonic  acid  and  water  to  produce  formic  aldehyde,  which,  by 
polymerization,^  becomes  starch,  thus  :  COg  +  HgO  =  CHgO  (formic  alde- 
hyde)-fOgj  then  6CH20  =  CgHj20g;  and  CgH-^20g  (grape  sugar)  -  HgO 
=  C(.Hjq05  (starch).  But  the  starch  is  really  formed  by  the  dissocia- 
tion of  the  protoplasm  under  the  action  of  the  chlorophyll,  so  that 
the  process  may  be,  first,  the  formation  of  formic  aldehyde,  then  the 
building  up  of  the  protoplasm,  and  finally  a  dissociation  of  the  proto- 
plasm, one  of  the  products  being  starch.  In  addition  to  starch,  sugars, 
fats,  cellulose,  and  organic  non-nitrogenous  acids  may  be  formed.  In 
a  similar  manner,  nitrogenous  bodies  may  be  built  up,  although 
physiological  chemists  have  not  advanced  so  far  in  this  direction. 
It  has  been  supposed  that  nitrates  and  sulphates  absorbed  as  food 
may  be  decomposed  by  organic  acids  (oxalic  acid)  and  that  the 
nitric  and  sulphuric  acids  thus  set  free  may  combine  with  a  non- 
nitrogenous  organic  substance,  such  as  formic  aldehyde.  Again, 
bodies  of  the  nature  of  amides  (that  is  ammonias  in  which  hydro- 
gen is  replaced  by  the  radicle  of  an  organic  acid),  such  as  asparagin, 

1  Polymeric  is  a  term  given  by  Berzelius  to  organic  compounds  possessing  the 
same  composition  but  differing  in  molecular  weight. 


24  INTRODUCTIOX. 

leucin,  etc.,  may  be  fonncd  either  as  steps  towards  the  Imikliug  up 
of  protoplasm  or  as  products  in  its  destructive  metabolism.  For 
our  present  piu'posc  it  is  sufficient  to  note  that  nitrogenous  matters 
may  also  be  formed  synthetically. 

Now  arises  the  question  as  to  the  source  of  the  enei-gy  that  enables 
the  protoplasm  of  the  i)lant-cell  containing  chli)ro})hyll  to  perform 
these  remarkable  synthetic  processes.  There  can  l)e  no  doubt  that 
the  energy  is  the  radiant  energy  of  light,  more  especially  of  the  red 
and  blue  rays  absorbed  by  chlorophyll.  It  has  been  ascertained  that 
a  solution  of  chlorophyll  presents  certain  absorjition  bands  Avhen  ex- 
amined with  the  spectroscope.  It  is  the  light  of  just  those  parts  of 
the  spectrum  that  is  most  active  in  the  decomposition  of  carbonic 
acid  by  green  plants,  and  it  is  remarkable  that  the  maximum  amount 
of  absorption  of  light  liy  chlorophyll  occurs  at  that  part  of  the  spec- 
trum where,  according  to  Langley,  of  America,  we  have  the  maximum 
of  energy.  Fiuther,  Engelmann  has  showTi  that  bacteria,  placed  along 
with  a  filament  of  Cladophora  in  the  solar  spectrum  under  the  micro- 
scope, collect  roimd  the  filament  in  those  regions  that  coincide  with 
the  absorption  bands  of  chlorophyll,  and  that  this  is  an  indication  of 
oxygen  being  evolved  from  the  chlorophyll  coiijuscles  in  the  Cladoi^hora, 
more  especially  where  they  are  exposed  to  raj-s  of  the  spectrum 
at  the  junction  of  the  orange  and  the  red  and  also  at  the  blue,  just 
beyond  the  line  F.  Light  has  been  found  to  have  an  influence  even 
on  the  absorption  of  food  materials  by  the  roots.  The  initiation  of 
these  changes  is  due  to  heat,  a  somewhat  elevated  temperature  being 
essential  to  the  active  life  of  all  plants;  but  in  the  later  stages,  the 
heat,  as  a  soiu'ce  of  energy,  is,  relatively  to  the  light,  of  less  import- 
ance. The  importance  of  light  to  the  plant  can  hardly  be  overstated. 
Keep  a  green  plant  in  darkness  and,  although  it  may  appear  to  groAV, 
it  loses  weight  by  the  exhalation  of  carbonic  acid  and  watery  vapour, 
and  if  kept  too  long  in  darkness  it  will  die.  Under  the  influence  of 
light,  assimilation  will  go  on  and  the  plant  will  gain  in  Aveight.  The 
true  respiration  of  the  plant  does  not  seem  to  be  affected  by  light. 
Thus  a  plant  containing  chlorophyll  lives  on  simple  food  elements 
and,  iinder  the  influence  of  light,  bmlds  these  up  into  more  complex 
substances.  In  doing  this,  the  kinetic  energy  of  light  is  stored  up 
and  becomes  potential.  Such  products  as  starch,  gums,  glutin, 
cellulose,  may  be  regarded  as  matter  containing  stores  of  energ}\ 
They  may  be  decomposed  by  various  chemical  operations,  or  they  may 
be  completely  oxidized  and  converted  into  carbonic  acid  and  water, 
but  in  these  oxidations  heat  w-ould  again  become  kinetic  and  could  be 
employed  to  do  work.      Thiis  the  fiirnace  of  a  steam-engine  might  be 


GENE  HAL  PRINCIPLES  OF  BIOLOGY.  25 

fed  with  starch  or  vegetable  oil  and  the  energy  liberated  from  these 
might  to  a  certain  extent  be  converted  into  motion.  The  green  plant 
then,  from  the  dynamical  point  of  view,  is  storing  up  energy.  On  the 
■other  hand,  plants  destitute  of  chlorophyll  cannot  live  on  such  simple 
materials  as  can  green  plants,  nor  can  they  obtain  energy  directly 
from  the  radiant  energy  of  the  sun.  Like  animals,  they  require 
food  containing  complex  organic  matters  representing  potential 
energy.  Both  classes  of  plants,  however,  expend  energy,  either  as 
^owth,  as  movement,  as  heat  (more  especially  during  germination 
^nd  at  certain  stages  of  the  reproductive  process),  or,  to  a  small 
extent,  as  light  or  electricity.  The  green  plant  stores  more  energy 
than  it  expends :  it  is,  as  already  explained,  more  concerned  in 
building  up  complex  substances  than  in  decomposing  these  into 
simpler  ones,  and  hence  the  life  and  growth  of  such  a  plant  is 
practically  unlimited.  Thus,  immense  accumulations  of  energy  have 
been  made  and  are  being  daily  made  by  the  vegetable  world,  and 
the  energy  of  the  sun's  rays  is  being  stored  up,  to  be  liberated  again 
as  heat  in  combustion,  or  as  heat  or  motion  in  the  bodies  of  living 
.animals. 

We  have  now  to  consider  the  question  from  the  point  of  view  of 
the  animal  kingdom.  Some  of  the  lowest  forms  of  animals  originate 
by  a  fission  or  division  of  the  parent  organism,  but,  above  this  low 
level  of  existence  all  originate  in  a  cell,  the  o\Tim,  or  egg.  After 
fecundation,  this  structure  passes  through  numerous  stages  of  de- 
velopment until  the  body  of  the  animal  is  formed.  During  this 
process  of  growth  the  animal  requires  food,  and,  like  the  plant,  it 
■also  requires  a  supply  of  energy  to  carry  on  the  internal  changes  in 
its  body,  possibly  to  move  its  body  from  place  to  place  and  to  supply 
energy  for  an  expenditure  going  on  in  the  form  of  heat,  and  to  a 
•smaller  degree,  of  electricity  and  of  light.  In  the  first  instance, 
■energy  as  heat  is  required  to  start  the  processes  of  assimilation  and 
of  growth.  The  development  of  all  ova  requires  certain  favourable 
conditions  as  regards  temperature;  but,  like  the  plant,  neither  the 
ovum  nor  the  adult  animal  form  receives  in  the  form  of  heat  more 
than  a  small  fraction  of  the  energy  it  needs.  Heat  in  both  instances 
initiates  or  provides  suitable  conditions  for  the  changes  in  the  body 
peculiar  to  life,  and  it  will  presently  be  seen  that  the  production  of 
Jieat,  and  thus  of  the  condition  favourable  to  living  actions,  is  one  of 
the  invariable  accompaniments  of  such  actions.  Food  is  now  supplied. 
With  the  exception  of  oxygen,  no  matter  can  be  used  by  an  animal 
in  the  form  of  an  element,  nor  can  an  animal  live  on  the  comparatively 
simple  compounds  that,  as  we  have  seen,  constitute  the  food  of  plants 


26  INTRODUCTION. 

Animals  obtain  oxygen  from  the  air,  or,  in  the  case  of  aquatic  organisms^ 
from  the  oxygen  dissolved  in  the  Avater.  The  food-stuffs,  -with  the 
exception  of  a  few  Rim})le  com})ounds  such  as  water,  common  salt,  etc., 
are  derived  either  from  the  bodies  of  other  animals  or  from  plants, 
and  a  little  consideration  will  show  that  all  food-stuffs  must  ultimately 
have  been  derived  from  plants.  Substances,  then,  formed  in  plants 
constitute  the  food  of  animals.  These  food-stuffs  have,  as  already 
explained,  been  constructed  by  the  plant  and  they  represent  energy 
in  the  potential  condition.  The  substances  essential  to  the  formation 
of  a  diet  for  an  animal  derived  directly  from  plants  con-sist  of  (1) 
albuminous  or  proteid  matters,  as  represented  hj  glutin  or  legumin ; 
(2)  fatty  matters,  such  as  olive  oil ;  (3)  carbo-hydrates,  such  as  starch, 
sugar,  gum;  (4)  mineral  matters — phosphates,  sulphates,  chlorides  of 
the  alkalies  and  alkaline  earths,  and  iron ;  and  (5)  water.  All  of 
these,  after  undergoing  various  changes,  chemical  and  physical,  are 
ultimately  assimilated  by  the  living  matter  of  the  animal's  body  and 
pass  through  metabolism  of  the  most  complicated  kind.  Thus,  part 
of  the  matter  mav,  by  constructive  metabolism,  be  built  up  into  the 
tissues  of  the  animal,  bone  and  muscle  and  nerve  and  the  tissues  of  the 
various  organs ;  another  portion  may  also,  after  constructive  metabolism, 
be  stored  up  as  reserve  material  in  the  form  of  fat  and  glycogen  ;  whilst 
a  third  portion  ma}',  by  destrvictive  metabolism,  be  split  up  into 
simpler  substances  which  may  be  excreted  without  having  entered 
into  the  composition  of  the  body.  Most,  if  not  all,  of  these  opera- 
tions are  intimately  connected  with  oxidations.  Oxygen  is  absorbed 
in  respiration  and,  directl}^  or  indirectly,  it  combines  Avith  the  matter 
in  the  food-stuffs  and  simpler  products  are  formed.  It  is  not  im- 
probable that,  in  the  first  instance,  constructive  metabolism  occurs 
by  which  the  oxygen,  proteids,  fats,  carbo-hydrates,  salts,  and  water- 
are  built  up  into  the  highly  complex  matter,  living  protoplasm,  and 
that  thus  there  is,  for  a  short  period,  a  still  further  conversion  of  energy 
into  the  potential  condition  even  in  the  animal.  This  condition,  how- 
ever, does  not  last.  Animal  protoplasm  is  characterized  by  molecular 
instability  :  its  large  and  complex  molecule  can  exist  only  in  very 
limited  conditions,  and  a  sudden  change  in  these  conditions,  or  what 
is  termed  a  stimulus,  causes  it  to  break  up  into  simpler  bodies.  Thus 
energy  is  liberated  and  appears  in  the  kinetic  form  as  heat,  and  probably 
as  motion.  The  decomposition,  in  the  first  instance,  of  li-vdng  protoplasm 
is  like  a  molecular  explosion,  shattering  the  complex  molecule  into 
fragments.  These  fragments,  however,  may  still  be  complex,  and  the 
process  may  be  repeated,  simpler  bodies  being  formed,  and  ultimately 
Ave  find  that  the  matter  throAvn  out  of  the  body  as  useless  is  carbonic- 


GENERAL  PRINCIPLES  OF  BIOLOGY. 


27 


acid,  water,  a  nitrogenous  substance  called  urea  (two  molecules  of  am- 
monia in  wliich  two  atoms  of  hydrogen  are  replaced  by  CO),  and 
saline  matters.  Tbese  substances  represent  only  a  small  amount  of 
energy,  and  it  will  be  observed  that  they  are  essentially  the  same  as 
the  simple  substances  constituting  the  food  of  the  plant.  Thus  the 
complex  bodies  built  up  by  the  plant  may  become  for  a  time  part  of 
the  still  more  complex  living  matter  of  the  animal,  and  then,  by  oxi- 
dations, this  complex  living  matter  is  decomposed  into  simpler 
matters.  In  the  latter  operation,  energy  is  set  free  and  appears  in 
the  kinetic  form  as  heat,  motion,  electricity,  light,  and  sound.  Thus 
the  body  of  animals  produces  heat  ;  there  are  movements  of  the 
whole  body,  as  in  locomotion,  or  of  portions  of  it,  as  in  the  respiratory 
movements  or  the  beating  of  the  heart ;  and  to  a  smaller  extent, 
electricity  (especially  in  electric  fishes),  light,  and  sound  may  be 
manifested.  Energy  becomes  kinetic  chiefly  as  heat  and  motion, 
and  even  motion  (internal  and  external)  is  ultimately  resolved  into 
heat. 

Contrast  now  the  plant  and  the  animal — the  plant  transforms  kinetic 
into  potential  energy,  the  animal  transforms  potential  into  kinetic 
energy.  But  neither  the  plant  nor  the  animal  is  wholly  concerned  in 
the  one  operation.  The  j^lant  also  converts  potential  into  kinetic 
energy,  but  relatively  to  a  small  extent;  whilst  the  animal  also  converts 
kinetic  into  potential,  but  relatively  to  a  small  extent.  It  will  be 
observed,  finally,  that  whilst  the  plant  furnishes  potential  energy  to  the 
animal,  and  the  animal  liberates  this  as  kinetic  energy,  the  kinetic 
energy  of  the  animal  is  not  re-transformed  into  the  potential  energy 
of  the  plant.  The  plant  must  therefore  always  receive  new  supplies 
of  energy  from  the  solar  rays. 

The  following  illustration   "wdll  still  further  elucidate  this  interest- 
ing subject.     It  is  well  known  that 
muscles  and  nerves  may  exhibit  some 
of   their  vital  properties  after  the 
death  of  the  animal  and  that  this 
is  especially  the  case  with  the  so- 
called  cold-blooded  animals  such  as 
the  frog.     Suppose  a  preparation  is 
made    consisting    of     the    gastroc- 
nemius  muscle   of    the   frog    "with 
sciatic  nerve  attached,  as  in  Fig.  1 4. 
an  instrument  termed  a  myograph,  one  form  of  which  is  sho\^Ti  in  Fig. 
15.    The  upper  end  of  the  femur  is  secured  by  the  clamp  C,  sliding  on  the 
pillar  B,  and  the  tendo  Achilles  (./  in  Fig.  14)  is  attached  by  a  hook  to 


Fig.     14. — Xerve  -  muscle     Preparation.       F, 
femur ;    JV,  nerve ;    J,  aperture  for  hook. 

This  preparation  is  connected  with 


28 


INTRODUCTION. 


the  horizontal  lc^•el•  A7i,  whicli  carries  a  marker  ,/.•  this  marker  is 
brought  into  contact  with  G,  a  smoked  ghiss  plate  that  can  be  moved 
horizontally  in  sliding  grooves.  The  nerve  is  stretched  over  wires  coming 
from  a  battery  or  induction  coil,  so  that  it  may  be  irritated  by  an  electric 
current.  When  the  nerve  is  irritated  the  muscle  contracts,  lifts  up  the  lever 
EE,  and  the  marker  /  draws  a  ^■ortical  line  on  the  plate  G.    The  plate  is 


Fig.  15. — Myograph,  an  instrument  for  recording  the 
conti-action  of  a  muscle.  A,  wooden  stand;  B,  vertical 
brass  pillar ;  C,  sliding  forceps  or  clamp  for  holding  upper 
end  of  femur  of  nerve-muscle  preparation  ;  D,  D,  short 
vertical  piUars  on  the  top  of  which  the  lever  EE  works  ; 
F,  scale  pan  for  weight  ;  /,  marker ;  G,  glass  plate  ;  K, 
counterpoise  to  keep  /  in  contact  with  G  ;  H,  counter- 
poise to  lever  EE.  The  nerve-muscle  preparation  is 
covered  with  a  glass  shade,  to  the  walls  of  which  pieces  of 
wet  blotting  paper  are  attached,  thus  forming  a  moist 
chamber  to  preserve  the  nerve  from  drying. 

then  pushed  on,  the  nerve  again  stimulated,  and  thus  a  series  of  vertical 
lines  is  obtained,  indicating  the  work  done  by  the  muscle  in  lifting  a  weight 
placed  on  the  scale  pan  F.  (See  Fig.  16.)  It  can  thus  be  shown  that 
the  muscle  does  work  in  lifting  the  Aveight,  and  by  a  refined  method  of 
inquiry  it  can  also  be  demonstrated  that  with  each  muscular  contraction 
heat  is  produced.  Energy  thus  becomes  kinetic  as  heat  and  motion. 
This  energy  is  not  derived  from  the  battery  used  in  irritating  the  nerve. 


GENERAL  PRINCIPLES  OF  BIOLOGY.  29 

The  electricity  is  used  merely  as  a  stimulus  to  the  nerve.  When  the 
nerve  is  irritated  a  molecular  change  is  generated  in  the  nerve ;  this 
travels  down  the  nerve  with  a  certain  velocity  (nerve-current),  and  when 


Fig.  16.— Examples  of  tracings  taken  with  myograph.     Plate  moving  in 
direction  of  arrow. 

it  reaches  the  muscle  it  sets  up  molecular  changes  in  it  Avhich  result  in 
a  contraction,  attended  by  the  phenomena  of  heat  and  motion.  Nor  is 
there  any  quantitative  relation  between  the  strength  of  the  electric  cur- 
rent employed  in  irritating  the  nerve  and  the  amount  of  work  done  by 
the  contracting  muscle.  A  very  feeble  current  would  be  quite  sufficient, 
just  as  the  pull  of  a  hair-trigger  would  be  enough  to  set  free  the 
energy  from  a  charge  of  gunpowder  in  a  rifle.  The  energy  then  that 
has  become  Idnetic  as  heat  and  motion  was  stored  up  in  the  muscle. 
Further,  it  might  be  shown  that  the  contraction  of  the  muscle  is 
associated  Avith  chemical  changes  in  it,  the  splitting  up  of  its  complex 
protoplasm  into  simpler  bodies.  Thus  energy  is  liberated  in  accordance 
with  the  principles  already  explained.  This  energy,  potential  in  the 
muscle  substance,  must  have  been  derived  from  the  food  of  the  frog, 
and  if  we  trace  back  the  history  of  this  food  we  find  it  came  originally 
from  plants,  and  that  the  plants  formed  it  from  simple  materials,  in  the 
processes  transforming  the  energy  of  light  into  potential  energy. 
Finally,  at  one  end  of  the  chain  we  have  matter  in  the  form  of  simple 
substances  along  Avith  the  kinetic  energy  of  light,  and  at  the  other  we 
have  again  matter  in  the  comparatively  simple  conditions  of  carbonic 
acid,  water,  and  nitrogenous  substances,  and  kinetic  energy  as  heat  and 
motion.  This  experiment  also  shows  that  muscle  substance  may  be 
regarded  as  a  magazine  or  store  of  energy,  which  may  be  liberated 
by  the  molecular  action  of  the  nerve.  We  shall  find  many  examples  of 
this  important  relation  between  nerve  and  muscle  and  between  the 
external  modes  of  energy  and  the  action  of  living  matter.  Just  as  nerve 
energy  liberates  the  energy  of  the  muscle,  so  light  and  sound  liberate 
the  energies  of  the  sense  organs  on  which  they  act,  and  these  again 
liberate  energies  in  the  nerve  centres,  which  in  turn  liberate  the  energy 
stored  up  in  muscle  or  gland. 

6.  Evolutional  History  of  Living  Beings. — The  evolution  of  a 
living  being  is  determinate :  it  has  a  commencement,  an  existence,  and  an 


30  INTRODUCTION. 

end;  it  passes  through  different  phases,  which  succeed  regularly  and  in  a 
certain  order.  The  same  statements  ma}/  be  made,  with  a  certain 
amount  of  truth,  regarding  a  crystal,  but  its  life  history  is  distinguished 
from  that  of  a  living  animal  by  the  absence  of  -waste  and  of  repair,  and 
by  its  mode  of  gro\\'th,  already  referred  to. 

Living  beings  have  a  certain  individuality.  Among  the  higher  grades 
each  member  has  a  certain  independence,  although  related  to  all ;  but 
this  characteristic  may  almost  disappear  in  the  lower  classes  of  plants 
and  of  animals. 

All  ^^dng  organisms  take  their  origin  in  a  germ  which  was  developed 
in  a  parent — that  is  a  previously-existing  being  having  essentially  the 
same  structure  and  properties.  Every  plant  and  animal,  accordingly, 
have  the  power,  at  one  stage  of  their  existence,  of  producing  a  germ  by 
which  the  species  may  be  perjjetuated.  This  germ,  which  is  known  as 
the  spore,  seed,  or  egg  of  plants  and  animals,  is  a  cell — the  simplest 
form  of  structure.  After  its  separation  from  the  parent  body,  it  is 
capable  of  independent  existence,  and,  under  favourable  external 
influences,  of  groAving  or  developing  into  a  new  individual,  in  most 
respects  similar  to  that  from  which  it  derived  its  origin. 

Living  beings  have  formed  a  continuous  series,  from  the  first  appear- 
ance of  life  upon  the  earth  until  now.  Offspring  usually  possess  more 
or  less  of  the  character  of  their  parents ;  and  they  may  transmit  pecu- 
liarities— either  acquired  by  new  conditions  of  existence,  or  received 
from  their  parents — to  their  descendants.     This  is  known  as  heredity. 

The  evolution  of  energy  undergoes  changes  diuring  the  life  of  an 
organism.  Usually  the  production  of  energy  increases  up  to  a  certain 
maximum,  and  then  slowly  declines,  so  that  in  the  life  history  of  each 
individual  there  is  a  period  of  maximum  vital  activity.  In  certain  species 
of  animals,  however,  there  are  successive  phases  of  rej^ose  and  of 
movement,  as  in  the  encysted  conditions  of  infusoria,  the  meta- 
morjDhoses  of  insects,  and  the  occrurence  of  hybernation.  In  other 
organisms  also,  vital  phenomena  may  appear  to  be  entirely  suspended 
under  certain  conditions.  For  instance,  some  of  the  rotiferce  may  be 
kept  in  a  state  of  dormant  vitality  for  a  considerable  time  by  the  simple 
process  of  drying. 

During  its  life  an  organism  undergoes  change  of  form,  increase 
of  ita  mass,  and  development  of  its  organization.  This  development 
is  not,  however,  continued  indefinitely.  The  organization  becomes  at 
last  complete  for  each  organism,  reproductive  functions  are  exercised, 
and  then  gradually  the  Avear  and  tear  become  greater  than  the  power 
of  upbuilding,  and  the  organism  breaks  down.  Death  at  last  neces- 
sarily terminates  its  evolution.     "NMien  this  occurs,  the  body  is  sub- 


GENERAL  PRINCIPLES  OF  BIOLOGY.  31 

mitted  to  the  action  of  external  agencies,  botli  physical  and  chemical, 
which  ultimately  reduce  it  to  the  simple  elements  of  which  it  was  at 
first  composed. 

It  is  important  to  remember  that  an  organism  is  affected  during 
■every  instant  of  its  life  by  the  medium  in  which  it  lives.  The  medium 
furnishes  the  materials  requisite  for  existence.  Dead  matter  is  supplied 
to  take  the  place  of  Kving  matter,  and  external  modes  of  energy — such 
as  heat  and  light — act  upon  it  at  the  same  time.  There  is  thus  an 
•action  and  reaction  between  the  organism,  and  the  conditions  in  which 
it  lives.  These  conditions  may  be  conveniently  summarized  by  the 
term  environment  In  this  adaptation  of  relations  every  living  organism 
has  a  power  of  suiting  itself  to  modifications  of  conditions  %vithin 
certain  limits.  This  power  is  known  as  its  variability,  and  it  is  a 
necessary  condition  of  the  existence  of  every  living  being. 

To  recapitulate,  the  essential  characters  of  a  living  being  are  the 
following : — 

1.  Molecular  complexity;   heterogeneity  of  parts;  and  chemical  in- 

stability of  the  organic  compounds  forming  it. 

2.  Waste  and  incessant  repair  of  organic  materials. 

3.  The  conversion  of  kinetic  into  potential  energy  as  the  framework 

of  the  body  is  built  up  or  stores  of  reserve  material  are  formed. 

4.  Liberation  of  kinetic  energy  in  various  modes,  and,  in  particular, 

as  mechanical  movement,  heat,  and  electricity. 

5.  Organization,  or  the  adaptation  of  certain  parts  of  the  body  to 

particular  functions. 

6.  A  regular  evolution  from  origin  to  death. 

7.  Origin   from   a   parent,    and   the   possibility    of    producing    the 

elements  of  offspring. 

8.  A  power  of  variability  and  of  adaptation  to  external  conditions. 

6.  Theories  of  Life. — Numerous  efforts  have  been  made  to  define 
life,  of  which  the  follomng  are  examples  : — Aristotle  says,  "  Life  is  the 
assemblage  of  the  operations  of  nutrition,  gTOwth,  and  destruction;" 
Lamarck  states  that  "  Life,  in  the  parts  of  the  body  possessing  it,  is 
that  state  which  permits  organic  movements,  and  the  movements 
which  constitute  active  life  result  from  the  application  of  a  stimulus ; " 
Bichat  says,  "Life  is  the  sum  total  of  the  functions  which  resist 
death;"  Treviranus  calls  it  "The  constant  uniformity  of  phenomena, 
with  diversity  of  external  influences;"  Laurence  says,  "It  consists  in 
the  assemblage  of  all  the  functions  or  purposes  of  organized  bodies, 
and  in  the  general  result  of  their  exercise ;"  Duges  calls  it  "  The  special 
activity  of  organized  bodies ;"  Beclard's  definition  is  "  Organization  in 


32  INTRODUCTION. 

action ;"  and  Herbert  Spencer  asserts  that  "  Life  is  the  continual 
adaptation  of  internal  relations  Avith  external  relations."  It  will  be 
observed  from  the  above  definitions  that  authors  have  felt  the  necessity 
of  presupposing  some  organized  structure,  the  existence  of  which  is 
taken  for  granted  in  their  definitions.  The  dictum  of  B^clard, 
"  Organization  in  action,"  is,  on  the  Avhole,  the  best. 

In  the  history  of  physiology  several  distinct  schools  of  thought  have 
from  time  to  time  had  the  ascendency.  Aristotle  and  Galen  laid  the 
foundations  of  anatomy,  and  in  their  physiological  speculations  they 
adopted  the  leading  tenet  of  Hippocrates  that  there  exists  a  principle 
Avhich  he  termed  </)vo-ts,  nature,  to  which  were  ascribed  the  origination 
and  control'  of  all  bodily  actions.  This  intelligent  principle  directed 
the  operation  of  other  subordinate  principles  or  faculties  {^ivaims), 
Avhich  carried  out  the  various  functions.  In  the  middle  ages,  a  school 
arose,  the  iatro-chemists  (larpos,  a  surgeon  or  physician,)  which  ascribed 
all  vital  phenomena  to  the  operation  of  chemical  laws,  and  more 
especially  to  fermentations  which  took  place  in  the  blood  and  other 
fluids.  This  school,  represented  by  Paracelsus,  Van  Helmont,  and 
Mayow,  may  be  regarded  as  the  offspring  of  the  Alchemists.  Then 
came  the  iafro-mathematicians,  who  attained  their  greatest  celebrity  in  the 
17th  century,  and  who  ascribed  vital  actions  to  the  sizes  of  particles 
and  pores,  the  amount  of  retardation  from  friction,  and  other  mechanical 
causes,  and  who  indeed  asserted  that  all  the  phenomena  of  life  arc 
mechanical.  Borelli,  Boerhaave,  and  De  Gorter  may  be  taken  as 
representatives  of  these  views.  This  school  was  succeeded  by  the 
animists,  founded  by  Stahl,  who  reverted  essentially  to  the  more  ancient 
doctrine  of  the  existence  of  a  rational  principle  as  the  cause  of  life. 
The  archeus,  psyche,  anima,  soul,  mind,  were  all  names  given  to  this 
principle  by  "WTiters  previous  to  Stahl,  but  Stahl  especially  termed  it 
the  anima.  It  was  not  the  soul  in  the  modern  sense ;  it  was  a 
mysterious  power  affecting  all  vital  operations,  sometimes  consciously, 
sometimes  not.  It  is  remarkable  how  these  old  views  still  exert 
an  influence  both  on  scientific  and  on  popular  thought.  Crystal- 
lized in  the  form  of  language,  these  ideas  have  passed  on  from 
generation  to  generation,  so  that  such  terms  as  derivation,  revulsion, 
resolution,  fermentations,  the  vis  medicatrix  naturce,  vital  force,  still 
may  be  employed  -without  reference  to  the  philosophical  systems  that 
gave  them  birth.  Further,  it  may  be  said  that  even  scientific  opinion 
oscillates  amongst  these  contending  modes  of  thought,  and  that  now 
and  again  views,  physiological  or  pathological,  are  enunciated,  which 
are  only  repetitions,  in  modern  language,  of  ancient  theories.  The 
error  in  all  these  schools  was  to  attribute  the  actions  of  the  li^ang  body 


GENERAL  PRINCIPLES  OF  BIOLOGY.  33 

solely  to  chemical,  mechanical,  or  vital  causes.  Modern  thinkers 
endeavour  to  study  the  phenomena  as  they  find  them,  to  explain  such 
of  these  as  can  be  accounted  for  by  the  application  of  physical  and 
chemical  principles,  and  leave  the  remainder  unexplained.  This 
unexplained  residue  is  termed  vital,  but  without  any  assumption  of  the 
existence  of  a  special  principle  or  vital  force,  and  the  more  refined  and 
accurate  our  means  of  research  become  the  more  limited  is  the  sphere 
of  the  phenomena  assigned  to  vital  force. 

To  obtain  a  clear  vieAV  of  Avhat  is  meant  hj  the  living  state,  consider 
the  phenomena  manifested  by  a  unicellular  organism  such  as  an 
amoeba,  or  by  a  living  cell,  such  as  a  colourless  blood  corpuscle,  or  a 
cell  from  a  gland,  or  a  cell  from  a  nerve  centre.  These  show  two  or 
more  of  the  following  properties — (1)  a  power  of  assimilation,  that 
is,  of  absorbing  dead  matter  and  of  converting  it  by  metabolism  into 
living  matter,  or  protoplasm ;  (2)  irritahility,  or  the  property  of 
])eing  affected  by  a  stimulus,  such  as  electricity  or  light,  and  of 
Adsibly  responding  to  it  by  movement ;  (3)  secretion,  or  the  elaboration 
from  protoplasm  of  new  substances,  as  the  formation  of  the  con- 
stituents of  milk  in  the  cells  of  the  mammary  gland ;  (4)  automatic 
molecular  changes,  leading  to  the  apparently  spontaneous  liberation  of 
energy,  as  in  the  nerve  cells  of  certain  nerve  centres  ;  and  (5)  repro- 
duction, or  the  giving  off  of  beings  or  living  things  similar  to  themselves. 
These  properties  are  termed  vital.  Wherever  they  are  manifested, 
Ave  say  the  thing  is  alive.  All  dogmatic  statements  as  to  the  nature  of 
life  can  only  be  misleading,  inasmuch  as  in  the  present  state  of  science 
our  knoAvledge  of  vital  processes  is  limited,  and  it  is  probable  that  the 
molecular  changes  associated  Avith  vital  phenomena  may  never  be 
thoroughly  understood.  AYhat  is  termed  vital  may  simply  be  a 
condition  of  matter,  like  the  phenomena  usually  called  physical ;  but 
even  if  it  Avere  found  to  be  so,  life  Avould  be  none  the  less  mysterious. 

Consult  Herbert  Spencer — Principles  of  Biology,  vol.  I.,  part  I.,  chaps. 
2,  3,  5,  6  ;  Beaunis — Physiologie  Humaine,  vol.  I.  ;  Carpenter,  on  the  Mutual 
Relations  of  the  Vital  and  Physical  Forces — Philos.  Trans.  1850  ;  also,  Quarterly 
Journal  of  Science,  vol.  I.,  1864  ;  Joseph  le  Conte— The  Correlation  of  Physical, 
Chemical,  and  Vital  Force,  and  the  Conservation  of  Force  in  Vital  Phenomena — 
Philos.  Mag.,  1860;  Groves — The  Correlation  of  the  Physical  Forces;  Vixes 
—Physiology  of  Plants,  Lectures  V.,  VIIL,  XIII. ,  and  XIV. 


3-t 


SECTION  II. 

THE  CHEmSTRY  OF  THE  BODY. 

Chap.  I.— THE  INORGANIC  CONSTITUENTS. 

Before  considering  the  structure  and  functions  of  the  tissues  and 
organs,  Ave  ought  to  become  accj[uainted  "snth  the  general  facts  of  animal, 
or  as  it  is  sometimes  termed  physiological  chemistry.  These  facts 
relate  either  to  the  nature  of  the  chemical  compounds  of  which  the  body 
is  composed  or  to  the  chemical  processes  connected  -sWth  the  phenomena 
of  life.  The  inquirer,  however,  soon  ascertains  that  there  are  special 
difficulties  in  the  study  of  this  branch  of  chemistry.  In  the  first  place, 
li\dng  matter  cannot  be  analyzed,  because  in  the  very  processes  of 
analysis  to  which  it  is  subjected  it  ceases  to  be  Kving,  and  the  results 
obtained  show  only  the  constitution  of  dead  matter  that  once  was  alive. 
Thus,  suppose  a  chemist  attempted  the  analysis  of  a  piece  of  living 
muscle,  the  processes  to  which  it  was  subjected  would  kill  it,  and  the 
joroducts  of  analysis,  such  as  proteid  matter,  fatty  matter,  saKne  matter, 
and  water,  would  only  be  the  substances  existing  in  dead  muscle.  Such 
an  analysis  would  not  throw  much  light  on  the  chemical  natiu-e  of  the 
li\-ing  protoplasm  on  the  acti\'ity  of  which  the  irritability  and  contrac- 
tility of  the  muscle  depended.  Again,  in  the  second  place,  the  chemical 
reactions  occurring  in  the  body  are  so  modified  in  amount  and  character 
by  the  nature  of  the  K-\dng  matter  in  which  they  occur  as  to  be  obscm-e 
and  difficult  of  interpretation,  and  the  most  profound  acquaintance  with 
organic  chemistry  and  vrith  molecu.lar  physics  is  recpiired  for  their 
elucidation.  For  example,  every  one  is  familiar  "with  the  well  known 
fact  that  in  respiration  oxygen  is  absorbed  by  the  blood  from  the  air- 
ceUs  of  the  lungs  whilst  carbonic  acid  is  given  off  bj'  the  blood  to  the  air, 
and  j^et  the  exact  natiire  of  these  interchanges  is  far  from  being  thoroughh" 
nnderstood.  How  far  these  interchanges  depend  on  physical  conditions, 
and  how  far  on  the  chemical  combinations  or  decompositions  occurring 
in  the  blood,  are  c[uestions  that  must  be  considered,  while  the  chemical 
constitution  of  haemoglobin,  the  colouring  matter  of  the  blood,  and  the 


THE  INORGAJIC  CONSTITUENTS.  35 

chemical  constitution  of  other  substances  in  the  blood,  recpire  careful 
investigation.  Still,  with  all  its  difficulties,  animal  chemistry  is  makino- 
rapid  progress,  and,  as  will  be  shown  in  discussing  the  chemical  oper- 
ations occurring  in  living  matter,  it  is  affording  glimpses  of  the  molecular 
machinery  of  life. 

If  a  human  body  were  analyzed,  the  substances  obtained  would 
depend  upon  the  methods  employed  and  the  extent  to  which  the  analysis 
was  pursued.  The  chemist  might  resolve  it  into  the  elements  of  which 
it  was  composed,  or  he  might  only  isolate  certain  compounds  formed  by 
these  elements.  Compounds  exist  of  greater  or  less  complexity.  Thus 
there  are  bases  and  acids,  and  the  salts  formed  by  their  union.  Still 
more  complex  bodies  exist  of  the  nature  of  fats  and  starch-like  com- 
pounds, whilst  there  are  substances,  such  as  albumin  or  haemoglobin,  of 
the  highest  degree  of  chemical  complexity. 

The  elements  foimd  in  the  body  are  hydrogen,  carbon,  nitrogen, 
oxygen,  sulphur,  phosphorus,  fluorine,  chlorine,  silicon,  sodium,  potas- 
sium, calciimi,  magnesium,  lithium,  iron,  and  occasionally  manganese, 
copper,  and  lead.  The  relative  importance  of  these  in  organic  matter 
has  already  been  discussed. 

The  compounds  formed  from  these  elements  are  either  of  the  nature  of 
proximate  principles,  or  they  exist  in  such  principles  (see  p.  15),  and  they 
are  primarily  diAdded  into  (1)  inorganic,  and  (2)  organic  compounds. 
The  inorganic  comprise  such  substances  as  water,  common  salt,  and 
phosphate  of  lime ;  whilst  the  organic  are  such  as  sugar,  stearin,  and 
albumin.  According  to  modern  views,  all  the  latter  fall  into  the 
domain  of  organic  chemistry,  that  branch  of  the  science  dealing  with 
carbon  and  its  compounds. 

The  inorganic  compounds  consist  of  water,  acids,  and  salts. 

1.  Water,  H.,0,  forms  about  two  thirds  of  the  weight  of  the  body,  so 
that  a  body  weighing  about  75  kilogrammes  contains  about  50  kilo- 
grammes of  water.  The  proportion  of  water  to  soKd  matter  is  greatest 
in  embryonic  tissues,  and  becomes  smaller  and  smaller  as  life  goes  on. 
Thus,  according  to  BischoflF,  the  body  of  an  infant  may  contain  664  parts 
of  water  to  336  of  solid  matter,  whilst  in  adult  life  the  proportions  may 
be  585  to  415  per  1000.  Beaunis  gives  the  following  table,  compiled 
from  the  analyses  of  Gorup  Besanez  and  others,  showing  the  quantities 
of  water  in  some  of  the  tissues,  organs,  and  fluids — 


30 


THE  CHEMISTRY  OF  THE  BODY. 


Liquids.  Water. 

Blood,    -         -  -  -  791 

Bile,       .         -  -  -  8()4 

Milk,      -        -  -  -  891 

Liquor  sanguinis,  -  -  901 

Chyle,    -         -  -  -  928 

Lymph,           -  -  -  958 

Serum,  -         -  -  -  959 

Gastric  juice,  -  -  973 

Intestinal  juice,  -  -  975 

Tears,     -         -  -  -  982 

Aqueous  humour,  -  986 

Cerebro-sjiinal  fluid,  -  988 

Saliva,   -         -  -  -  995 

Sweat,   -         -  -  -  995 


Solid 
Parts. 

209 
130 
109 
99 
72 
42 
41 


18 

14 

12 

5 

5 


Tissues  or  Organs.                   Water.  ^^^^^ 

Enamel,           -  -         2  998 

Dentine,          -         -  -  100  900 

Bone,     -         -         -  -  486  514 

Fat,        -        -  -  299  701 

Elastic  tissue,         -  -  496  504 

Cartilage,       -         -  -  550  450 

Liver,    -        .        .  .  693  307 

Spinal  cord,  -         -  -  697  303 

White  substance  of  brain,  700  300 

Skin,      -         -         -  -  720  280 

Brain,    -         -         -  -  750  250 

Muscles,         -         -  -  757  243 

Spleen,  -         -         -  .  758  242 

Thymus,         -         -  -  770  230 

Connective  tissue,  -  -  796  204 

Kidneys,         -         -  -  827  173 

Grey  substance  of  brain,  858  142 

Vitreous  humour,  -  -  987  13 


An  adult  introduces  into  the  body  daily  about  2  litres  of  water  in  the 
form  of  drinks  of  various  kinds,  whilst  it  may  be  estimated  that  about 
I  litre  is  contained  in  the  articles  of  diet  consumed.  In  addition  to 
this  a  small  amount  is  probably  formed  in  the  body  by  chemical  pro- 
cesses. In  ordinary  circvm^stances  about  1500  cub.  cent,  are  elimin- 
ated daily  by  the  kidneys,  800  to  1000  cub.  cent,  by  the  skin  and  lungs, 
and  100  cub.  cent,  by  the  intestine.  There  is  thus  in  a  state  of  health 
an  equilibrium  established  between  the  amount  absorbed  and  the  amount 
eliminated.  If  the  amount  falls  below^  a  certain  minimum  the  sensation 
of  thirst  referred  to  the  pharynx  is  experienced,  and  if  the  quantity  be 
still  further  reduced  there  wall  be  distiu-bances  of  the  circulation  and  of 
respiration,  such  as  irregular  action  of  the  heart  and  difficulty  in  breath- 
ing and  even  diminution  of  sensibility  and  con\'Tdsive  seizures.  Death 
has  been  observed  to  occur  in  frogs  when  the  loss  of  water  amounted  to 
30  per  cent,  of  their  weight.  On  the  other  hand,  the  excessive  absorp- 
tion of  w'ater  into  the  blood  and  tissues  is  not  harmless.  In  these 
circumstances  the  kidneys  secrete  a  large  quantity  of  urine  of  low^ 
si^ecific  gravity  and  the  total  elimination  of  solids  in  a  given  time  is  also 
increased.  Thus  the  blood  and  tissues  become  impoverished  as  to  saline 
matters.  There  has  also  been  observed  in  such  cases  a  tendency  to 
dropsical  eflfusions.  According  to  Talk  and  Picot  an  injection  into  the 
jugular  vein  of  a  rabbit  or  dog  of  from  -J-g-  to  -5'^  of  its  w- eight  of  w^ater 
caused  death.  Picot  found  also,  as  had  been  previously  stated  by 
Richardson,  that  the  injection  of  water  altered  the  appearance  of  the 
coloured  blood  corjmscles,  and  he  attributed  the  cause  of  death  to  inter- 
ference with  their  resj^iratory  functions.^ 

The  water  of  the  body  is  the  general  solvent,  thus  producing  the 
^  Picot,  Comptes  Sendus,  1 874,  p.  62. 


THE  INORGANIC  CONSTITUENTS. 


37 


physical  condition  favourable  to  chemical  operations,  and  the  molecules 
of  matter  in  solution  are  brought  into  such  close  proximity  as  to  permit 
of  those  subtle  interactions  connected  "vvith  the  phenomena  of  life.  As 
a  general  rule  (and  with  the  exception  of  such  a  tissue  as  exists  in  the 
vitreous  humour  of  the  eye)  the  greater  the  degree  of  activity  of  a  tissue 
or  organ  the  greater  is  the  amount  of  water  it  contains. 

2.  Mineral  Matters.  These  are  chiefly  chloride  of  sodium,  chloride 
of  potassium,  sulphates  of  soda  and  potash,  phosphates  of  soda,  potash, 
lime,  and  magnesia,  and  carbonates  of  soda  and  lime.  There  are  also 
small  quantities  of  iron  and  silica.  The  following  tables  from  Beaunis 
show  the  percentage  of  mineral  matters  in  the  ash  of  certain  organs  and 
of  certain  fluids — 


Table  I. — Mineeal  Matters  in 

Certain  Animal  Solids. 

Names  of  Authors  of  Analyses. 

Heintz. 

Staffel. 

Breed,    i      "^^t- 

c. 

Oidt- 

Schmidt. 

mann. 

Bone. 

Muscles 
of  Calf. 

Braiii. 

Liver. 

Lungs. 

Spleen. 

Chloride  of  Sodium. 

10-59 

4-74 

13-0 

Chloride  of  Potassium, 

... 

Soda,  -       -       -       -       - 

2-35 

10-69 

14'51 

19-5 

44-33 

Potash,      -       -       -       . 

34-40 

34-42 

25-23 

1-3 

9-60 

Lime,  ----- 

37-58 

1-99 

0-72 

3-61 

1-9 

7-48    , 

Magnesia,  -       -       -       - 

1-22 

1-45 

1-23 

0-20 

1-9 

0-49 

Oxide  of  Iron,  - 

... 

2-74 

3-2 

7-28 

Chlorine,  -       -       -       - 

2-58 

0-54 

Fluorine,   -       -       -       - 

1-66 

Free  Phosphoric  Acid, 

9-15 

Combined  Phos.  Acid, 

53-31 

48-13 

39-02 

o6-18 

48-5 

27-10    i 

Sulphuric  Acid, 

0-75 

0-92 

1-4 

2-54    ' 

Carbonic  Acid, 

5-47 

Silicic  Acid,     - 

0-81 

012 

0-27 

0-17 

Phosphate  of  Iron, 

1-23 

Table  II. — Mineral  Matters  in 

Certain  Animal 

Fluids. 

Names  of  Authors  of  Analyses. 

i    ^ 

■§ 

.2 

M 

ZV 

-e 

^■•i 

d 

> 

^ 

o 

^^ 

OS 

o 

Ph 

Blood. 

Serum. 

Blood 

Clot. 

Lymph. 

Urine. 

Milk. 

Bile. 

Excre- 
ments. 

Chloride  of  Sodium,    - 

58-81 

72-88 

17-36 

74-48 

67-26 

10-73 

27-70 

4-33 

Chloride  of  Potassium, 

29-87 

26-33 

Soda,        -       -       -       . 

4-15 

12-93 

3-55 

10-35 

1-33 

36-73 

5-07 

Potash,     -       -       -       - 

11-97 

2-95 

22-36 

3-25    13-64 

21-44 

4-80 

6-10 

Lime,        .       -       -       . 

1-76 

2 -28 

2-58 

0-97      1-15 

18-78 

1-43 

26-40 

Magnesia, 

1-12 

0-27 

0-53 

0-26      1-34 

0-87 

0-53 

10-54 

Oxide  of  Iron, 

8-37 

0-26 

10-43 

005       ... 

0-10 

0-23 

2-50 

i  Phosphoric  Acid,  - 

10-23 

1-73 

10-64 

1-09    11-21 

19  00 

10-45 

36-03 

Sulphuric  Acid,     - 

1-67 

2-10 

0-09 

2-64 

6-39 

Carbonic  Acid, 

1-19 

4-40 

2-17 

8-20       ... 

11-26 

Silicic  Acid,    - 

0-20 

0-42 

1-27      4-06 

■ 

0-36 

3-13 

38  THE  CHEMISTRY  OF  THE  BODY. 

On  considering  these  tables,  we  may  note  the  folk) wing  points  : — 
(1)  That  about  |-  of  the  total  mineral  matter  in  the  solids  con- 
sist of  phosphoric  acid  and  of  lime ;  (2)  the  large  amounts  of  potash 
and  of  phosphoric  acid  in  muscle ;  (3)  the  large  amounts  of  potash 
and  of  phosphoric  acid  in  the  brain ;  (4)  the  contrast  as  regards 
potash  especially  between  the  analyses  of  the  liver  and  of  the  lungs ; 
(5)  the  large  amounts  of  soda  and  oxide  of  iron  in  the  spleen  ;  (6)  the 
contrast  of  the  analyses  of  blood,  blood  serum,  and  blood  clot  as  regards 
chloride  of  sodium,  potash,  and  phosphoric  acid ;  (7)  the  general 
resemblance  of  lymph  and  urine  to  serum,  except  as  regards  potash 
and  soda;  (8)  the  large  amount  of  chloride  of  potassium  in  blood 
clot  and  its  absence  from  serum ;  (9)  the  large  amounts  of  chloride 
of  potassium,  lime,  and  phosphoric  acid  in  milk;  and  (10)  the  large 
amount  of  soda  in  bile.  It  will  be  observed  that  the  analyses  do  not 
state  precisely  the  amount  of  the  various  salts  that  are  assumed  to 
exist,  but  only  the  quantity  of  bases  and  of  acids,  and  it  would  be 
impossible  to  allocate  to  the  bases  the  requisite  quantity  of  acids  to 
form  salts.  Further,  the  phosphoric  and  sulphuric  acids  obtained 
in  such  analyses  are  derived  partly  from  the  decomposition  of 
organic  compounds,  and  they  do  not  all  exist  in  the  tissues  in  com- 
bination with  bases.  It  will  therefore  be  seen  that  an  analysis  of 
the  ash  gives  only  an  imperfect  view  of  even  the  inorganic  com- 
pounds. To  get  an  approximate  estimate  of  the  amount  of  the  more 
important  salts  another  method  is  adopted  in  place  of  analyzing  the 
ash,  namely,  that  of  estimating  the  quantity  of  the  salt  absorbed  and 
eliminated  daily. 

1.  Chloride  of  sodium  and  potassium} — The  chief  saltof  sodium  is  chloride 
of  sodium  (NaCl)  or  common  salt,  which  exists  in  all  the  tissues  and  in 
all  the  fluids.  Probably  200  grammes  may  be  taken  as  the  average 
amount  in  the  1)ody  of  an  adult.  From  15  to  20  grammes  are 
eliminated  daily  chiefly  in  the  urine,  whilst  a  smaller  amount  is 
separated  in  sweat  and  in  the  excrements.  To  make  up  for  this 
daily  loss,  common  salt  is  taken  in  food,  either  as  an  ingredient  of 
the  food-stuff  or  as  an  adjunct.  In  carnivora,  the  amount  in  the  food  is 
sufficient  for  the  wants  of  the  organism ;  but  herbivora  and  man  appear 
to  require  an  additional  quantity.  Bunge  states  that  the  food  of  herbi- 
vora is  rich  in  carbonates,  phosphates,  and  sulphates  of  j^otash,  and  that 

^  The  tests  for  the  mineral  substances  are  no  doubt  familiar  to  the  student,  and 
the  chemical  processes,  volumetric  or  gravimetric,  by  which  the  amount  of  each 
constituent  may  be  ascertained,  will  be  described  iu  treating  of  the  methods  of 
analyzing  the  urine.  The  student  of  medicine,  in  particular,  should  make  himself 
conversant  with  the  more  common  reactions  of  the  inorganic  substances. 


THE  INORGANIC  CONSTITUENTS. 


39 


these  salts,  reacting  on  the  chloride  of  sodium  in  the  blood,  are  decom- 
posed, chloride  of  potassium  (KCl)  and  phosphates,  carbonates  and 
sulphates  of  soda  being  formed.  These  salts,  then,  in  excess  in  the  blood, 
are  eliminated  by  the  urine,  Avhilst  the  deficiency  of  chloride  of  sodium 
must  be  met  by  additional  supplies  in  the  food.  On  the  other  hand 
the  food  of  carnivora  is  deficient  in  salts  of  potash,  and  thus  the 
amount  of  chloride  of  sodium  in  the  food  is  quite  sufficient  as  less 
of  it  is  used  in  the  manner  indicated.  If  chloride  of  potassium  be 
substituted  for  chloride  of  sodium,  disturbances  arise  by-and-bye 
from  a  deficient  amount  of  the  latter  salt.  The  tissues,  however, 
retain  common  salt  very  tenaciously,  so  that  during  a  dietary  devoid 
of  salt,  the  salt  disappears  slowly  from  the  urine.  (Beaunis,  op.  cit. 
vol.  i.  p.  79.) 

A  portion  of  the  salt  thus  introduced  may  be  supposed  to  pass  through 
the  body  unchanged,  but  during  its  passage  no  doubt  affecting  nutri- 
tive processes.  Thus  it  facilitates  the  absorption  of  albuminous 
matters,  and  it  increases  the  metabolic  changes  in  the  blood  or 
tissues,  as  shown  by  the  increased  amount  of  urea  eliminated  in  the 
urine  after  the  administration  of  salt.  As  already  explained,  a  portion 
of  the  common  salt  taken  in  food  is  decomposed,  giving  its  chlorine  to 
produce  chloride  of  potassium,  a  salt  indispensable  to  muscular  fibres 
and  to  the  blood  corpuscles.  The  relative  amounts  of  chloride  of 
sodium  and  of  chloride  of  potassium  in  some  of  the  principal  fluids  is 
shown,  per  1000  parts,  in  the  folloAving  table — 


Blood,     

Blood  Coi-puscles, 

Vl&sva&i,  [Liquor  Sanyuinis),    -       -       -       - 

Lymph,  - 

Chyle, 

Gastric  Juice, 

Pancreatic  Juice  (from  permanent  fistulse), 
Pancreatic  Juice  (from  temporary  fistula), 
Bile,        ....-.--- 

Milk, -      - 

Urine, 


NaCl. 

KCl. 

2-70 

2-05 

3-67 

5-54 

0-35 

5-67 

5-84 

1.45 

0-55 

2-50 

0-93 

7-35 

0-02 

5-53 

0-28 

0-S7 

2-13 

11-00 

4-50 

2.  Salts  of  Soda  and  Potash. — This  table  shows  that  the  blood  cor- 
jiuscles  are  rich  in  KCl,  and  the  plasma  rich  in  NaCl,  and  it  is  a 
general  fact  that  KCl  exists  largely  in  the  solid  parts  such  as  blood 
corpuscles,  musciilar  fibre,  and  nervous  tissues,  while  NaCl  exists  in  the 
fluids  of  the  body.  At  one  time  it  was  supposed  that  the  salts  of 
potash  had  a  high  nutritive  value,  but  the  experiments  of  Panum  in- 
dicate that  this  is  not  strictly  the  case.     No  doubt,  as  a  rule,  animals 


40 


THE  CHEMISTRY  OF  THE  BODY 


thrive  better  on  a  diet  containing  salts  of  potash,  hut  in  small  doses 
these  have  a  stimulant  rather  than  a  nutritive  action,  increasing 
especially  the  action  of  the  heart,  both  as  regards  force  and 
frequency  of  beat.  In  larger  doses  the  activity  of  the  heart  is 
"weakened. 

It  would  appear  that  salts  of  soda  are  more  abundant  in  embryonic 
and  early  life  than  in  adult  life.  Thus,  Bunge  found  that  for  each 
Idlogramme  of  weight  there  were  the  folloAving  proportions  of  soda 
and  potash — 


Rabbit's  Embryo,    - 
Rabbit,  14  days  old,       - 
Kitten,  1  day  old,    - 
Cat,  19  days  old,      - 
Cat,  29  days  old. 
Dog,  4  days  old. 
Adult  Mouse,     - 

XaoO. 

K.O. 

2-183 

1  -630 
2-666 
2-285 

2  292 
2-589 
1-700 

2-605 
2-967 
2-691 
2-790 
2-684 
2-667 
3-280 

3.  Salts  of  ammonia. — Ammonia  may  lie  foimd  in  the  urine,  sweat, 
and  gastric  juice.  About  -7  gramme  is  eliminated  daily  by  the 
urine,  and  the  urine  of  herbivora  contains  less  than  that  of  carnivora. 
Thus,  Salkowsky  shows  that  in  normal  acid  urine  the  ratio  of  ammonia 
to  the  total  nitrogen  is  from  1  to  17  to  1  to  20-5,  while  in  the  alka- 
line urine  of  the  rabbit  it  is  from  1  to  54  to  1  to  57.  It  is  well 
known  that  under  the  action  of  an  organic  ferment  (see  Urine), 
ammonia  ax'ises  from  the  decomposition  of  urea,  and  it  has  been 
suggested  that  possibly  the  small  amount  found  in  the  urine,  and  in 
the  sweat  or  expired  air,  may  arise  from  the  decomposition  of  urea 
in  the  intestine,  the  ammonia  formed  being  absorbed  by  the  blood- 
vessels and  then  eliminated  by  the  kidney.  (Beaunis.)  In  normal 
circumstances,  there  is  no  decomposition  of  urea  in  the  blood  leading 
to  the  formation  of  carbonate  of  ammonia,  and  Feltz  and  Hitter  found 
that  this  did  not  occur  even  after  injecting  the  ammoniacal  ferment 
into  the  blood. 

4.  Salts  of  Lime. — Fluoride  of  calcium  and  phosphate,  carbonate,  sul- 
phate, urate,  and  oxalate  of  lime  exist  in  the  body.  The  fluoride  is  found 
in  the  enamel  of  tooth  and  in  bone.  Phosphate  of  lime  is  found 
everywhere,  but  more  especially  in  the  bones  and  teeth,  which  may 
contain  from  60  to  70  or  80  per  cent,  of  this  salt.  In  these  structures 
it  exists  as  the  tribasic  phosphate  (Ca32P04).  The  ash  of  all  tissues, 
except  elastic  tissue,  contains  phosphate  of  lime,  and  urine  contains 
phosphate  of  lime  in  sobition,  whilst  alkaline  urine,  as  in  herbivora, 
shows  it  in  a  state  of  suspension.    (Beaiuiis.)     Carbonate  of  lime  exists 


THE  INORGANIC  CONSTITUENTS.  41 

in   the   otoliths    (Fig.   17)   or   concretions  in  the  internal  ear,  in  the 
urine,  in  saliva  and  salivary  concretions,  and   along  with  phosphate 
of  lime  in  the  bones,   teeth,  and  hairs.      Sulphate  of  lime  has  been 
found  in  bone,  in  the  blood,  and  in 
pancreatic  juice,    whilst   urate   and 
oxalate  oi   lime  appear  in  urinary 
deposits.      The   salts    of    lime   are 
derived  from  the  food,  more  espe- 
cially from  vegetable  products  and 
from  water,  in  which  lime  exists  as 
bicarbonate.     It  would  appear  that 
even  the  small  amount  present  in 
ordinary  water  may  be  sufficient  for 
the  wants  of  the  organism.      The 

carbonate     in     the     food     or     in     the     Fig.  17.— otoliths  of  carbonate  of  lime,  con- 

T  IT-  T         i-  sisting    (if    small    thick    oolumnar    crystals, 

water    is    changed    durmg    digestion     combinations  of  rhombohedrons  and  hexagonal 

into    phosphate,     and    this    passes   p"®™®' 

into  the  blood  and  tissues.  Valentin  supposed  that  this  change  of 
carbonate  into  phosphate  might  go  on  even  in  the  tissues,  as  he  found 
that  young  bones  were  rich  in  carbonate  of  lime,  and  that  the  carbonate 
^ave  place  to  the  phosphate  as  the  bones  grew  older.  Another  source 
■of  carbonate  of  lime  might  be  found  in  the  formation  of  carbonic  acid 
from  the  decomposition  of  such  organic  acids  as  tartrates,  malates, 
citrates  during  their  passage  through  the  body.  Salts  of  lime  are 
eliminated  by  the  bowels  and  kidneys,  in  herbivora,  chiefly  by  the 
former  channel,  and  in  carnivora  by  the  latter.  The  special  function 
■of  the  lime  salts  is  to  give  firmness  and  solidity  to  the  tissues,  more 
especially  to  the  bones.  If  supplied  in  deficient  amount,  or  if  they 
are  removed  from  the  solid  tissues  to  too  great  an  extent,  the  bones 
in  particular  may  be  imperfectly  developed,  or,  yielding  to  the 
superincumbent  weight,  they  may  become  deformed.  Further,  it 
appears  that  when  food  or  drink  contains  too  little  of  the  salts  of 
lime  for  the  wants  of  the  body,  these  salts  are  taken  from  the  bones 
and  muscles,  indicating  that  they  may  have  some  other  part  to  play 
in  the  metabolism  of  the  body  with  which  we  are  unacquainted. 

5.  Salts  of  Magnesia. — Phosphate  of  magnesia  (Mg32P04)  is  usually 
found  in  small  amount  along  with  phosphate  of  lime  in  all  the  solids 
and  fluids.  Gorup  Besanez  states  that  in  muscles  and  in  the  thymus 
gland  the  amount  may  be  even  greater  than  the  amount  of  phosphate 
of  lime.  It  is  eliminated  by  the  kidneys  from  carnivorous  animals  as 
phosphate  held  in  solution  in  the  acid  fluid,  whilst  in  the  urine  of 
herbivora  it  exists  as  the  ammoniaco-magnesian,  or  triple  phosphate, 


42  THE  CHEMISTRY  OF  THE  BODY. 

or  as  the  i^hosphate  of  magnesia.  Excrements  iisiially  contain  the 
same  compound  salt,  along  with  palmitates  and  stearates  of  magnesia. 
The  function  of  magnesia  salts  is  unknown. 

6.  Iron  forms  an  essential  constituent  of  haemoglobin,  the  colouring 
matter  of  the  blood,  and  traces  exist  in  the  chyle,  lymph,  bile,  milk, 
urine,  gastric  juice,  pigment  of  the  eye  and  hair.  (Beaunis.)  The  blood 
of  an  adult  contains  about  3  grammes  of  pure  iron,  and  in  the  spleen  of 
the  dog  as  much  as  "24  gramme  per  100  volumes  has  been  found  hj  Picard. 
The  function  of  the  iron  has  to  do  A\dth  the  resi^iratory  properties  of 
haemoglobin,  the  substance  which  conveys  oxygen  from  the  lungs  to  the 
tissues.     It  is  daily  eliminated  in  the  faeces  as  the  sulphide  of  iron. 

7.  Hydrocliloric  Acid  (HCl)  exists  in  the  free  state  in  gastric  juice. 

8.  Phosphoric  Acid  and  Phosphates. — Phosi^horus,  combined  -with 
oxygen  to  form  phosphoric  acid  (PO^),  is  derived  from  lecithin,  nuclein, 
and  glycero-phosphoric  acids — three  complex  organic  bodies,  to  be 
considered  later — and  it  unites  with  soda,  potash,  lime,  and  magnesia 
to  form  the  various  phosphates  already  alluded  to.  There  are  three 
phosphates  of  soda :  (a)  Na,PO^,  {b)  Xa^HPO^,  and  (c)  NaH.PO^ ; 
three  i^hosphates  of  potash,  («)  K3PO4,  {h)  K2HPO4,  and  (c)  KHgPO^; 
two  phosphates  of  lime,  (a)  Ca32P04,  and  (&)  CiiM.^2V0^,  phosphate 
of  magnesia,  Mg32POi;  and  the  ammoniaco-magnesian,  or  triple  j^hos- 
phate,    NH^Mg^PO^  +  6H2O.      (Fig.  18.)     An    adult   man   eliminates 

by  the  kidneys  from  2*5  to  3*5  grammes 
of  phosphoric  acid  daily.  Carnivora 
eliminate  phosphates  chiefly  by  the  kid- 
neys, only  -^-Q  of  the  total  being 
separated  by  the  excrements  as  phos- 
phate of  lime  and  magnesia  ;  whereas 
in  herbivora  the  carbonates  replace  the 

Fig.  is. — Phosphate  of  ammonia  and  . 

magnesia— three-sided  prisms  bevelled     phosphateS    in    the    Unue,    and    the     phoS- 

.at  both  ends  and  on  one  of  the  edges.  ,  ^  •    n       •         i 

phates  appear  chiefl}^  in  the  excrements. 
Compounds  of  phosphorus  are  evidently  of  great  importance  in  the 
body,  as  indicated  by  their  presence  in  the  blood  corpuscles,  the 
muscles,  and  nervous  tissues. 

9.  Carbonates. — These  are  always  found  in  the  ash  of  animal  matters, 
l)ut  their  presence  may  be  due  to  the  decomposition  of  organic 
acids.  Still,  the  blood  contains  alkaline  bicarbonates  (NaHCOg  and 
KHCO3),  and  they  may  also  be  found  in  the  urine,  lymph,  and  saliva. 
Carbonates  are  derived  from  the  food,  directly  or  indirectly,  by  the 
decomposition  of  organic  vegetable  acids,  such  as  malic,  tartaric,  or 
citric  acids.  Again,  as  -will  be  seen  hereafter,  carbonic  acid  may  l^e 
regarded,  along  Anth  water,  as  the  last  of  the  series  of  bodies  produced 


THE  INORGANIC  CONSTITUENTS.  43 

by  the  decomposition  of  non-nitrogenous  matters  in  the  body,  such  as 
fats  and  carbo-hydrates. 

10.  Sulphates. — These  are  also  always  found  in  the  ash  of  animal 
matter,  but  as  sulphur  is  an  essential  constituent  of  albuminous  matter, 
the  sulphuric  acid  thus  found  arises  from  the  oxidation  of  the  sulphur 
during  the  process  of  incineration.  The  presence  of  sulphates  in  the 
ash  is  therefore  no  proof  of  the  existence  of  such  in  the  organic  matter. 
Sulphates,  hoAvever,  are  found  in  small  quantity  in  the  tissues,  in  the 
blood,  and  in  the  fluids,  except  milk,  bile,  and  gastric  juice.  (Beaunis.) 
These  are  derived  partly  from  the  food  and  partly  by  oxidation  of  the 
sulphur  in  albuminous  matter.  That  such  oxidations  do  take  place 
has  been  proved.  Doses  of  sulphur  are  followed  by  an  increase  in  the 
amount  of  sulphates  eliminated.  A  diet  rich  in  albuminous  matter 
produces  the  same  influ.ence,  whilst  a  vegetable  diet  has  the  reverse 
effect.  Possibly  albuminous  matters  may  be  decomposed,  and  sulphates 
be  thus  formed.  At  all  events,  the  increased  elimination  of  urea  fol- 
lowing a  diet  rich  in  albuminates  is  accompanied  by  an  apparently 
correlative  increase  in  the  amount  of  sulphates.  From  1'5  to  2 '5 
grammes  of  sulphuric  acid  are  excreted  by  the  kidneys  of  an  adult  man 
daily.  The  urine  may  also  eliminate  phenol-sulphuric  acid  and  con- 
jugated acids  of  a  similar  kind  to  the  extent  of  "2787  gramme  daily. 
{v.  Velclen.)  The  urine  of  cats  and  dogs  may  contain  alkaline 
hyposulphites.  The  excrements  contain  sulphide  of  iron,  and, 
by  the  decomposition  in  the  intestine  of  albuminous  matters  rich  in 
sulphur,  sulphuretted  hydrogen  may  l^e  produced. 

Chap.  II.— THE  CHEMICAL  CONSTITUTION  OF  THE  ORGANIC 
CONSTITUENTS. 

The  organic  compounds  obtained  from  the  body  of  a  plant  or  of  an 
animal  were  at  one  time  supposed  to  be  of  a  different  constitution  from 
those  of  inorganic  nature.  The  chemist  could  decompose  mineral  matters 
into  their  elements  and  he  could  build  them  vqy  again,  but  whilst  he  knew 
the  amount  of  carbon,  hydrogen,  and  oxygen  in  a  given  weight  of  starch, 
he  could  not  build  up  this  body  from  these  elements.  Hence  it  was 
assumed  that  the  laws  regulating  the  construction  of  the  complex  sub- 
stances present  in  living  bodies  were  different  from  those  which  rule  in- 
animate matter.  The  synthesis  of  urea — a  crystalline  body  found  in  the 
urine  in  1828  by  Wohler — disproved  this  notion,  and  since  then  many 
organic  bodies  have  been  built  up  by  the  chemist.  In  the  process,  some 
insight  has  been  obtained  into  their  chemical  constitution,  the  artificial 
distinction  between  inorganic  and  organic  chemistry  has  been  removed. 


44  THE  CHEMISTRY  OF  THE  BODY. 

and  Kekiile,  one  of  the  greatest  authorities  on  such  a  matter,  writes  as 

follows — 

"The  chemical  compounds  of  the  vegetable  and  animal  kingdom  contain  the 
same  elements  as  those  of  inanimate  nature.  "We  know  that  in  both  cases  the  same 
laws  of  combination  hold  good,  and  hence  no  difterences  exist  between  organic  ami 
inorganic  compounds,  either  in  their  component  materials,  or  in  the  forces  which 
hold  these  materials  together,  or  in  the  number  and  the  mode  of  grouping  of  their 
atoms.  We  notice  continuous  series  of  chemical  compounds  whose  single  members, 
when  only  those  which  lie  close  together  are  compared,  exhibit  strong  analogy,  so 
that  between  these  no  natural  di\-ision  is  perceptible.  If,  however,  for  the  sake  of 
perspicuity  a  line  of  demarcation  is  to  be  drawn,  we  must  remember  that  this 
boundary  is  purely  arbitrary  and  is  not  a  natural  one,  and  may  be  drawn  at  any 
point  which  seems  most  desirable.  If  we  wish  to  express  by  organic  chemistry 
that  which  is  usuallj-  considered  under  the  name,  we  shall  do  best  to  include  all 
carbon  compounds.  We,  therefore,  define  organic  chemistiy  as  the  chemistry  of 
the  carbon  compounds,  and  we  do  not  set  up  any  ojiposition  between  inorganic  and 
organic  bodies.  That  to  which  the  old  name  of  organic  chemistry  has  been  given, 
and  which  we  express  by  the  more  distinctive  term  of  the  chemistiy  of  the  carbon 
compounds,  is  merely  a  special  portion  of  pure  chemistry,  considered  apart  from 
the  other  portion  only  because  the  large  number  and  the  peculiar  importance  of 
the  carbon  compounds  render  their  special  consideration  necessary."  i 

Xotwithstanding  the  Aveight  of  Kekule's  great  authority,  it  must,  how- 
ever, be  said  that  in  the  above  passage  he  overshoots  the  mark,  and  that 
there  is  a  real  difference  in  character  between  organic  and  inorganic 
carbon  compounds.  Contrast,  for  example,  sugar  with  prussiate  of 
potash,  and  it  ^nll  be  seen  that  although  both  bodies  are  carbon 
compounds  they  are  tj-jDCS  of  structure  of  an  entirely  different 
character.  Organic  carbon  compounds  have  been  happily  defined  by 
Schorlemmer  as  hydrocarbons  and  their  more  immediate  derivatives,  and 
organic  chemistry  is  therefore  that  of  the  hydrocarbons.  This  definition 
is  probably  as  good  a  one  as  can  be  given  of  organic  substances. 

It  is  clear  then  that  we  have  to  do  now  "odth  the  chemistry  of  carbon 
compounds.  The  student  is  at  once  brought  face  to  face  with  a  vast 
series  of  bodies  the  chemical  constitution  of  which  is  represented  by 
complex  formulae,  and  he  soon  finds  also  that  the  same  substance  may 
be  represented  by  different  formulae  according  to  the  notions  of  the  com- 
position of  the  body  held  by  difi'erent  chemists.  It  is  of  interest  there- 
fore to  understand  what  such  formulae  mean  and  how  the  chemist  is  able 
to  represent  the  constitution  of  an  organic  l^ody  by  formula?,  because 
there  is  a  great  danger  of  attaching  too  much  importance  to  formulae  and 
of   imagining  that  they  really  represent  the  grouping  of  the  atoms. 

^  Kekule,  Lehrbuch  d.  Org.  Chemie,  i.  11.  The  above,  on  comparison  with  the 
original,  was  modified  from  the  translation  of  the  same  passage  given  in  Roscoe 
and  Sohorlemmer's  Treatise  on  Chemistry,  vol.  iii.  part  1,  p.  32. 


CHEMICAL  CONSTITUTION  OF  ORGANIC  CONSTITUENTS.     45 

AVithout  encroaching  except  to  a  very  limited  extent  on  the  pro- 
vince of  organic  chemistry,  it  will  be  useful  to  give  a  brief  account 
of  the  leading  conceptions  of  the  organic  chemist  in  this  most  difl&cult 
department  of  the  science. 

Carbon  is  the  one  element  essential  to  organic  compounds,  and  the 
peculiarities  of  the  chemical  substances  found  in  the  body  depend  to  a 
large  extent  on  the  chemical  properties  of  this  all-important  element. 
It  is  a  tetrad  element,  and  its  atomic  weight  (12)  is  capable  of  uniting 
with  at  most  four  atomic  weights  of  hydrogen  (1)  or  of  any  other  mon- 
atomic  element.  The  simplest  hydrocarbon  compound,  marsh  gas  or 
methane,  CH^^,  is  a  saturated  compound,  that  is,  methane  cannot  combine 
with  chlorine,  bromine,  or  other  monatomic  element,  but  one  or  more  of 
the  atoms  of  hydrogen  may  be  exchanged  for  an  equivalent  amount  of 
another  element.     Thus— 


Methane.            Meth}-!  Chloride. 

Methene  Cliloride. 

Chloroform. 

CH4                        CH3CI 

CH.Cl^ 

CHCI3 

Carbon  Tetra-chloride.     Carbonic  Acid. 

Hydrocyanic  Acid. 

Cyanogen  Chloride. 

CCI4                             CO2 

HCN 

CICN 

The  above  may  all  be  termed  substittition  derivatives  of  the  first  hydro- 
carbon, CHj.  But  carbon  may  unite  with  itself,  or,  in  other  words 
there  may  be  many  atoms  of  carbon  in  a  carbon  compound,  and  these 
may  unite  with  each  other  and  thus  add  greatly  to  the  complexity 
of  the  substance.  As  shown  by  Kekule,  it  is  this  fundamental 
property  possessed  by  carbon,  of  its  atoms  uniting  among  them- 
selves, which  distinguishes  it  from  all  other  elements,  and  this 
is  also  the  cause  of  the  large  number  of  bodies  that  may 
be  derived  from  the  different  groupings  possible  with  three  or 
four  or  more  carbon  atoms.  Thus,  if  two  atoms  of  carbon  com- 
bine, two  atomicities  of  the  group  are  satisfied  whilst  six  remain  free; 
if  three  atoms  of  carbon  combine,  there  are  eight  free  atomicities ;  and 
if  four  atoms  of  carbon  combine,  there  are  ten  free  atomicities ;  and  so 
on.  Each  of  these  free  atomicities  may  be  satisfied  by  combining  with 
one  of  a  monatomic  element — say  hydrogen — or  two  with  a  diatomic 
body — say  oxygen — and  in  this  way  the  compound  may  become  a 
saturated  compound,  which  cannot  combine  further  with  elementary 
bodies,  but  from  which  new  bodies  may  be  formed  by  substitution. 

The  addition  of  each  atom  of  carbon  to  the  end  of  the  chain  raises 
the  combining  power  of  the  substance  by  two.     Thus — 

H         HH         HHH         HHHH 

I  II  III  I   I   I   I 

H— C— H  H-C— C— H  H--C— C-C— H  H— C— U— C— C— H 

I  II  III  Jill 

H         HH         HHH         HHHH 

Four.  Six.  Eight.  Ten. 


46 


THE  CHEMIST liV  OF  THE  BODY 


So  that  7i-atoms  of  C  Avill  oombine  with  2/(  +  2  atoms  of  any  monatomic 
substance.  Each  of  these  saturated  compounds  is  the  basis  of  a  series  of 
bodies,  as  shown  in  the  following  table — 


Hydrocarbons. 

Alcohols. 

Aldebyde. 

Acids. 

Ketones. 

CnHju  +  j 

(./uxljn  +  .jU 

C„H,uO 

C„H.,„0, 

0„H,„0 

ch; 

CH40 

CH.,0., 

CaHg 

CoHgO 

C.H,0 

C..H40, 

... 

CsHg 

C^HsO 

c;hsO 

c.;Heo: 

C^HgO 

^411 10 

C.HjoO 

04H80 

C.HgO, 

C.HsO 

c'h;. 

C'sHisO 

C5H10O 

^"5^100.2 

C5H10O 

CgH|4 

CeHj.O 

CgHjoO 

CgHioO., 

CrHis 

QHieO 

C.H^ 

C-HhO, 

CsHi8 

CsHigO 

CsHieO 

CgHjgO, 

C<,H.,o 

CflH.joO 

^9^,30.2 

CjoHga 

CiqHo.jO 

C10H20O2 

CuH.24 

^12^-26 

Cv^-2,0, 

C13H28 

Cl4H;jO 

... 

C14H.28O2 

Each  of  the  individuals  in  this  series  of  hydrocarbons  ditfers  from  the 
one  above  it  by  CHg.  Such  a  series  is  termed  homologous,  and  it  is 
well  known  that  the  boiling  points  of  the  substances  in  a  homologous 
series  rise  by  nearly  equal  increments. 

Since  1862,  series  of  hydrocarbons  represented  by  CnH.2,,  +  2,  etc., 
have  been  grouped  under  the  name  of  paraffins.  It  was  found  that 
American  petroleum  contained  a  mixture  of  homologous  bodies  repre- 
sented by  this  formula,  and  their  relation  to  the  alcohols,  aldehydes, 
acids,  ethers,  etc.,  already  kno^vn  to  the  organic  chemist,  was  recognized. 
From  each  of  these  hydrocarbons  numerous  substitution  products 
may  be  obtained.  Thus,  from  any  body  having  the  general  formula 
CnHou  +  o  substances  may  be  derived  by  the  substitution  of  OH,  XH^, 
CHo .  OH,  CO .  OH  for  one  atom  of  H,  or  double  each  of  these  group.« 
of  OH,  etc.,  for  2H,  and  so  on.  Further,  from  each  hydrocarbon, 
CnHon  +  2,  by  theory  at  least,  compounds  poorer  in  hydrogen  are  formed 
by  the  Avithdrawal  of  one  or  more  couples  of  atoms  of  hydrogen,  and 
from  each  of  these  again  substitution  compounds  may  be  produced. 
Thus,  we  have  the  folloA^dng  series  of  non-saturated  hydrocarbons,  each 
of  which  mav  be  the  basis  of  a  group  of  chemical  substances' — 


CnHan 
CnsHsn  -  'J 
C„H2n-4 
CnH2u_6 
CnB[2n  -  8 


C.H,„_i4 

CuHon  -  IB 
CnHsn  - 18 
CiiH-in  -  22 
CuHo,,  _  04 
C11H2D  -  26 


Etc. 


CHEMICAL  CONSTITUTION  OF  ORGANIC  CONSTITUENTS.  47 

Thus,  the  series  C,^R,n  +  o,  as  shown  in  the  above  table,  contains 
the  well-known  monatomic  alcohols,  such  as  methyl,  ethyl,  and  propyl 
alcohols,  and  the  corresponding  acids — formic,  acetic,  propionic,  etc. 
The  second  series  (CnHa,,),  starting  with  olefiant  gas,  CgH^,  contains  the 
diatomic  alcohols  or  glycols,  GJi^n  +  ^^i,  and  the  acids  derived  from 
these:  (1)  acids  having  the  formula  CnHanO^,  such  as  giycollic  acid, 
and  (2)  acids  having  the  formula  CnHo^.^Oj,  of  which  oxalic  acid  is  a 
representative.  The  third  series  (C^Hon-o)  is  illustrated  by  acetylene, 
C^Hg;  the  fourth  series  (C„Hon_4)  by  terebinthene,  C^QH^gj  the  fifth 
series  (Ci^Hon-e)  hy  benzol,  C^Hg;  the  sixth  series  (Cj.Hsn-s)  ^^J 
cinnamene,  CgHg,  etc.  A  good  example  of  bodies  related  to  such  a 
series  as  any  of  the  above  we  have  in  the  fifth  series,  Ci^H2„_g  which 
gives  benzol,  CgHg,  and  it  in  turn  is  related  by  substitution  to 
numerous  bodies,  such  as  CgHj.OH,  CgHg .  COH,  CgHg .  CO .  OH, 
CgHg .  NH2,  etc.,  just  as  CH4  yields  the  corresponding  compounds, 
CH3.OH,  CH3COH,  CH3.CO.OH,  CH3.NH2,  etc.  There  is,  how- 
ever, a  far  greater  difference  betAveen  CH3 .  ISTH.^  and  CgH^ .  NH.,  than 
between  CH3 .  NHg  and  any  XH^  substitution  product  of,  for  instance, 
C0H4,  C3Hg,  etc.  So  marked  are  these  differences  that  the  benzol 
derivatives  are  classed  as  aromatic  compounds  to  distinguish  them  from 
the  more  immediate  derivatives  of  the  paraffins  which  are  termed  fatty 
compounds. 

Eeference  has  already  been  made  to  the  relation  of  the  alcohols  to 
the  paraffins.  Thus  they  may  be  represented  by  replacing  the  H  of 
the  hydrocarbon  by  OH.  They  are  therefore  substitution  derivatives, 
and  the  analogues  of  metallic  hydrates.  For  example,  beginning  with 
the  hydrocarbon  ethane,  C^Hg,  we  have  CgHg  .  OH,  ethylic  hydrate  or 
ethyl  alcohol,  analogous  to  Na .  OH,  sodium  hydrate.  In  like  manner, 
there  is  at  least  one  alcohol  for  each  hydrocarbon.  But  it  is  well 
known  that  there  are  alcohols  having  the  same  percentage  composition 
and  yet  differing  in  their  products  of  oxidation  and  decomposition. 
The  same  general  formula  therefore  might  represent  different  substances. 
For  example,  CgHgO  represents  propyl  alcohol,  but  it  is  well  known  that 
there  are  two  propyl  alcohols — the  one  yielding  by  oxidation  first  an 
aldehyde  and  then  an  acid,  and  the  second  a  ketone.  To  explain  this, 
the  chemist  devises  two  formulae.  He  supposes  that  in  primary  propyl 
alcohol  there  is  a  group  of  atoms,  CH^ .  OH,  which  is  monatomic, 
and  that  in  secondary  propyl  alcohol  there  is  a  diatomic  groujD, 
CH .  OH. 

CH, .  OH, 
Primary  propyl  alcohol  is  then  represented  by  the  formula    1 

C2H5 


48  THE  CHEMISTRY  OF  THE  BODY. 

and  secondary  proj)}'!  alcohol  by   CH .  OH.     In  the  oxidation  of  the 

6H3 

first,  the  aldehyde  is  formed  l)y  the  removal  of  the  H^,  from  the  group 

C.OH 
CH., .  OH,  leaving    1  ,    or   C.jHgO,  propyl   aldehj'de,  and  the  acid 

^2      5  (^Q     OH 

by   the   substitution   of   0  for  H.,  in  the  same  group  :     1  »  or 

C2H5 

CgHgOg,  propionic  acid.     Again,  in  the  case  of  the  oxidation  of   the 

secondary   propyl    alcohol,    a   ketone   is   formed   by   the    removal   of 

CH,  CH3 

HH  from  the  diatomic  group,  CH .  OH— thiis  :  CH  .  OH,  then  CO  ,  or 

I  I 

CH,  CH3 

CgHgO,  propyl  ketone,  or  acetone.  The  ketone,  when  oxidized,  cannot 
give  any  C,  acid,  because  the  group  COH  is  wanting;  it  yields  CO.,,  H^O 
and  acetic  acid.  In  like  manner  there  are  primary,  secondary,  and  ter- 
tiary amyl  alcohol,  and  four  butyl  alcohols  are  theoretically  possible. 

Compounds  therefore  having  the  same  percentage  elementary  com- 
position and  molecular  weight,  and  which  show  a  similar  behaviour 
under  certain  reactions,  whilst  they  differ  to  a  greater  or  less  extent  in 
other  reactions,  or  at  least  in  physical  properties  as  boiling  point, 
specific  gravity,  etc.,  ai-e  termed  isomeric.  Thus,  as  already  pointed 
out,  there  are  four  isomeric  butyl  alcohols,  all  having  the  same  formula, 
C4H9  (OH),  and  the  products  obtained  by  various  reactions  on  these 
are  also  isomeric.  Oxidation  of  the  first  butyl  alcohol  produces 
butyric  acid  (C^HgOg);  of  the  second,  isobutyric  acid  (C^HgO^);  of  the 
third,  ethylniethyl  ketone  (C4HgO) ;  and  of  the  fourth,  a  mixture  of 
acetic  and  formic  acids. 

Finally,  bodies  having  the  same  percentage  composition,  but  different 
molecular  weights  are  pobjmeric.  Thus,  aldehyde  C2H4O  and  CgH^.^Og 
paraldehyde,  are  polymeric;  and  the  same  is  the  case  mth  the 
hydrocarbons  of  the  general  formula  CnHon,  and  with  formal  alde- 
hyde, CH^O,  acetic  acid,  C2H4O2,  lactic  acid,  CyH^Og,  and  grape 
sugar,  CgH^206-  ^^  ^"^^^  ^^^  observed  that  the  molecular  weights  of  the 
polymeric  bodies  are  integer  multiples  of  the  same  empirical  formula. 

The  alcohols  hitherto  considered  are  monatomic,  but  there  are  also 
diatomic  and  triatomic  alcohols,  and  also  bodies  of  a  similar  kind 
referable  to  the  higher  series  of  hydrocarbons.  Thus  the  diatomic 
alcohols  or  glycols  are  represented  by  the  formula  C„H2„(OH)2.  It 
was  pointed  out  that  the  primary  monatomic  propyl  alcohol  contains 
the  group  of  atoms  CH, .  OH,  and  its  relation  to  the  primary  propyl 


CHEMICAL  CONSTITUTION  OF  ORGANIC  CONSTITUENTS.    49 

glycol  may  be  represented  by  supposing  two  sucb  groups  existing  in 

CHg.OH 
the  latter.     Thus     1     ^'        ^  or  CHg  ,  is  primary  propyl  alcohol, 

CH2  .  OH  ^2^5  CH3 

and  CH2  is  primary  propyl  glycol.     A  diatomic  alcohol  is  analo- 

CH2OH 
gous  to  the  oxide  of  a  dibasic  metal,  such  as  Ca(OH).,. 

Again,  we  find  the  triatomic  alcohol  haiang  the  general  formula 
C^Hon+aOs,  of  which  the  best  example  is  glycerine,  of  great  importance 
in  connection  with  the  chemical  constitution  of  the  fats,  as  will  be 
sho"\vn  in  another  chapter.  A  triatomic  alcohol  is  analogous  to 
Bi(0H)3. 

Another  group  of  bodies  constitutes  the  ethers  produced  by  treating 
the  alcohols  with  dehydrating  agents — 

2G2H5(OH)-H20=(C2H5)20,  or  CoHg-0-C,H5. 

Ethyl  alcohol.  Ethyl  ether.  Ethyl  ether. 

Observe  also  that  ethylic  ether  (02115)20  is  analogous  to  XagO,  sodium 
oxide ;  and  ethylene  ether,  CgH^O,  to  CaO,  calcium  oxide ;  and  glycerine 
ether  (03115)203,  to  81503,  bismuthic  oxide. 

By  the  oxidation  of  the  alcohols,  another  group  named  aldehydes  is 
formed.  They  are  bodies  intermediate  between  alcohols  and  acids,, 
and  they  may  be  described  as  hydrocarbons  in  which  the  monatomic 
radicle  group  COH  replaces  H  (Hydrocarbon,  CH^) — 

CoH5(0H)  +  0  =  CH3 .  COH  +  H,0. 

Ethyl  alcohol.  Ethyl  aldehyde. 

Further  oxidation  produces  the  corresponding  acids,  which  may  be  re- 
garded as  compounds  of  the  same  radicles  with  CO .  OH — 

CH3 .  COH  +  0  =  CH3 .  COOH. 

Ethyl  aldehyde.  Acetic  acid. 

Thus  each  alcohol  is  related  to  a  monobasic  acid,  and  we  have  COH .  OH, 
formic  acid  :  CgOHg .  OH,  acetic  acid ;  C3OH5 .  OH,  propionic  acid  ; 
C^OHy.OH,  butyric  acid ;  C5OH9.OH,  valerianic  acid  ;  and  CgOHi^^.OH, 
caproic  acid.  These  acids  form  metallic  salts,  com])ou7id  ethers,  amides^ 
and  haloid  derivatives.     Thus,  to  form  a  salt — 

2(CH3 .  CO .  OH)  +  K0CO3  =  2(CH3 .  CO .  OK)  +  CO.  +  H^O. 

Acetic  acid.  Acetate  of  potash. 

By  acting  on  ethylic  hydrate  with  acetic  acid,  acetic  ether  is  formed, 

thus — 

CH3 .  CO .  OH  +  C2H5 .  (OH)  =  CH3CO .  OC2H5  +  H2O. 

Acetic  acid.         Ethyl  alcohol.         Acetic  ether. 
I.  D 


50  THE  CHEMISTRY  OF  THE  BOUV. 

The  compound  ethers  in  tvirn,  ■when  acted  on  l)y  aninionia,  yii'l<l  aniidc^ 

and  the  corresponding  alcohol — 

CH3CO .  OC2H5  +  NH3  =  CH3CO .  NH,  +  C,H5(0H). 
Acetic  ether.  Monacetamide.      Ethyl  alcohol. 

Lastly,  amines  may  he  regarded  as  hydrocarhons  in  which  n(XH.^)  are 
substituted  for  nH . ,  and  they  are  termed  monamines,  diamines,  or 
triamines,  according  as  they  are  related  to  one,  two,  or  three  mole- 
cules of  ammonia,  thus — 


N 

CeHs 
H 
H 

N, 

^■•S: 

N3 

Phenylamine  or 

Phenylenerliamine 

Triamidobenzine 

Amidtibenzine, 

or  Diamidobcnzine, 

or  a  Triamine. 

aMc 

mamiue. 

a  Diamine. 

It  will  now  be  instructive  to  consider  shortly  how  the  chemist  is 
enabled  to  give  definite  formuli»  for  complex  organic  bodies,  so  that 
we  may  understand  what  such  formulae  imply. 

At  one  time  the  structure  of  an  organic  compound  was  ex})laine(l 
by  the  assumption  of  the  existence  of  hypothetical  groups  of  atoms 
or  radicles  which  Avere  made  to  take  their  place  in  various  so-called  tjrpcs, 
such  as  the  t^q^e  of  water,  of  ammonia,  or  of  marsh  gas.  It  is  noA\% 
however,  recognized  that  the  natiu-c  of  any  compound  is  completely 
determined  by  the  atomic  constitution  of  its  molecules.  Suppose,  for 
exa;mple,  a  substance  is  known  to  contain  3  atoms  of  carbon,  7  atoms 
of  hydrogen,  and  1  atom  of  chlorine  in  each  molecule,  that  is  C.jHyCl, 
there  are  at  least  two  ways  in  which  these  might  be  arranged  to  re- 
present tAvo  possible  compounds.     "We  might  have  the  arrangement — 

H    H    H  "                  H   H    H 

III  III 

(1)    H— C— C— C— CI,  (i-  (2)    H— C— C— C— H. 

ill  III 

H    H    H  H     CI  H 

A  third  body  is  impossible  according  to  theory,  and  this  is  corroljorated 

by  experience,  and  the  first  body  is  known  to  be  orthopropyl  chloride 

and  the  second  isopropyl  chloride,  bodies  presenting  certain  chemical 

differences,  but  isomeric.     Again,  take  C^H-Cl;  this  can  Ije  represented 

H    H 

I      I 
only  under  one  possible  form,  namely  H — C — C — CI ;  there  should  he 

I      I 
H    H 

only  one  chloride  of  ethyl,  as  is  the  case.     In  like  manner  we  find 

only  one  body,  ethyl  alcohol,  CoR^O,  haAang  the  arrangement  of  atoms 

H    H 

H — C — C — OH,  but  it  does  not  follow  that  we  have  only  one  body 

H    H  H  H 

I  I 

wnth  the  formula  CHeOj  and  we  accordingly  find  H — C — 0 — C — H, 

I  I 

H  H 


CHEMICAL  CONSTITUTION  OF  ORGANIC  CONSTITUENTS.    51 

methyl  ether.  A  formula  is  said  to  give  the  correct  grouping  of  the 
atoms,  if  it  indicates  correctly  how  a  body  may  split  up  into  two  or 
more  portions  and  how  it  may  be  synthetically  constructed.  It  usually 
accounts  for  all  we  know  of  the  chemical  natm^e  of  a  substance,  but  it 
often  expresses  a  great  deal  more  than  we  know  has  been  experi- 
mentally verified.  Thus,  take  Benzol,  CgHg;  it  is  clear  that  the  6 
atoms  of  C  might  be  strung  together  in  many  ways  so  as  to  leave 
six  surplus  affinities  for  the  6  atoms  of  hydrogen.  There  are  more 
than  30  different  possible  arrangements  by  which  this  might  be  accom- 
plished, but  only  one  benzol  is  known  to  exist.     According  to  Kekule 

the  constitution  of  benzol  is — 

H       H 
1  I 

C C 

/'     "\ 

H-Cg  X— H 

\.     ./ 

I  i 

H       H 

— that   is,  the  6  carbon  atoms  exist  in  a  closed  ring  and  every  two 

neighbouring  C's  are  united  alternately  by  a  single  and  a  double  band. 

According  to  this  hypothesis  there  should  be  only  one  CgHgCl,  but 

there  may  be  three  CgH^Cl^,  according  as  to  whether  the  chlorines  are 

placed  in  the  relative  positions  1  and  2,  or  1  and  3,  or  1  and  4.     That 

such  bodies,  and  only  such,  exist  has  been  proved  experimentally. 

Consideration  will  show  that  as  the  number  of  atoms  increases  the 
difficulty  becomes  greater  and  greater  of  determining  what  arrangements 
are  possible  and  what  are  not  possible,  and  as  pointed  out  to  me  by 
Professor  Dittmar,  we  now  want  a  km  of  Imitation,  by  which  it  may  be 
possible  to  determine  what  arrangements  exist  naturally  and  what 
cannot  exist.  ^ 

We  are  now  in  a  jDosition  to  understand  what  the  requirements  of  the 
chemist  are  before  he  can  construct  a  formula  indicating  the  structiu-e  of 
an  organic  body.  Such  formulae,  when  rightly  understood,  do  not 
pretend  to  express  the  arrangement  of  the  atoms  in  the  body.  Of  that 
nothing  is  known.  They  only  tell  how  the  body  "will  probably  behave 
in  various  chemical  reactions,  how  it  may,  as  it  were,  fall  to  pieces,  and 
how  it  may  be  possibly  reconstructed.  Chemical  formula  are  a  sym- 
bolic language  expressing  certain  ideas  in  the  mind  of  the  chemist,  and 
they  should  never  be  interpreted  as  dealing  with  the  atomic  constitution 
of  the  body  being  discussed. 

^  "What  we  call  'chemical  constitution'  is  the  constitution  not  of  the  body, 
but  of  its  formula."      (Dittmar.) 


52  THE  CHE}fISTRY  OF  THE  BODY. 

To  determine  a  chemical  formula  the  chemist  must  know  (1)  the  per- 
centage elementary  composition  of  the  body  as  ascertained  by  analysis;* 
and  (2)  the  relative  atomic  weights  of  H,  0,  C,  and  N,  namely  1,  16, 
12,  and  14;  (3)  then,  from  the  percentage  composition  and  the  relative 
atomic  weights  the  empirical  foraiula  is  obtained,  which  expresses  the 
simplest  ratio  of  the  weights  of  the  elements  entering  into  the  com- 
position of  the  substance;  and  (4)  the  specific  gravity  of  the  substance 
in  a  perfectly  gaseous  condition  is,  if  ])0SRil)lc,  determined,  and  it  is  well 
kno^\Ti  that  the  specific  gra-\dty  is  ])roportional  to  the  molecular  weight. 
From  these  data  the  formula  is  constructed,  and  then  the  possible 
arrangement  of  the  atoms  into  groups  is  decided  by  the  behaviour  of 
the  substance  iWth  reference  to  certain  chemical  reactions.  Take,  for 
example,  acetic  acid.  AMiy  is  its  formula  C^H^O^?  Empirically  it 
might  be  CHoO,  or  n(CHoO).  But  the  specific  gravity  of  acetic  acid 
vapour  is  30,  taking  that  of  hj-drogen  as  =  1 ;  hence  as  the  sp.  gr.  of  a 
molecule  of  hydrogen.  Ho  =  2,  that  of  a  molecule  of  acetic  acid  =  60, 
which  shows  the  formula  of  the  moleciile  to  be,  not  CHoO,  but  C^H^O.j. 
Again,  acetic  acid  forms  -with  sodium  the  salt  acetate  of  soda,  and  in 
the  reaction  one  fourth  of  the  hydrogen  is  expelled  for  each  equivalent 
of  the  sodium.  As  Hg  cannot  be  divided  into  fourths,  it  is  clear  that 
both  the  C  and  the  Ho  must  be  doubled  and  that  the  formula  of  the 
molecule  is  C^H^Oo.  In  like  manner,  when  chlorine  is  passed  through 
acetic  acid,  chloracetic  acid  is  formed,  and  for  each  atom  of  CI  one 
fourth  of  the  hydrogen  is  displaced,  again  pointing  to  the  molecular 
formula  CoH^Oo.  Apply  the  same  mode  of  observation  and  reasoning 
as  to  the  amount  of  0  in  acetic  acid.  "\Mien  acted  on  by  pentachloride 
of  phosphorus  half  of  the  oxygen  is  removed  to  form  chloride  of 
acetyl,  whilst  the  other  half  goes  -snth  the  phosphorus,  thus — 

C2H3O.HO  +  PCI5  =  CoH.O.Cl  +  HCl  +  POCL, 

Thus  there  must  be  more  than  1  atom  of  0  and  not  less  than  2. .  Lastly, 
as  to  the  number  of  atoms  of  carbon.  When  acetate  of  soda  is  heated 
Avith  caustic  potash,  carbonate  of  potash  is  formed  and  marsh  gas  escapes. 
The  C  is  thus  parted,  one  half  going  to  the  carbonate  and  the  other  to 
the  marsh  gas.  Consequently  there  must  be  at  least  2  atoms  of  C.  In 
the  case  of  acids  generally,  as  is  well  illustrated  with  reference  to  acetic 
acid,  another  method  is  to  prepare  the  silver  salt,  and  taking  Ag=  108, 
to  determine  the  relative  quantities  of  C,  H,  and  0,  in  combination  mth 
one  atom  of  silver.  In  this  case  for  108  parts  of  silver,  Ave  find  C  =  24, 
that  is  12x2;  H  =  3,  that  is  1  x  3;  and  0  =  32,  that  is  16  x  2.     Hence 

1  Details  as  to  the  methods  of  organic  analysis  may  be  found  in  any  standard 
chemical  work. 


CHEMICAL  CONSTITUTION  OF  ORGANIC  CONSTITUENTS.    53 

acetate  of  silver  is  C2H3Ag02,  or  n(C2H3Ag02).  But  acetic  acid  is 
monobasic,  and  there  is  only  one  potassium,  sodium,  or  silver  salt,  hence 
C^HgAgO^  must  be  the  formula  of  the  salt,  and  C^H^Oo  that  of  the 
acid. 

Lastly,  and  of  the  greatest  imjDortance,  the  chemist  must  study  the 
decompositions  of  the'J^ody  in  question,  and  observe  how  the  molecule 
divides  and  the  number  of  atoms  going  into  each  portion.  Suppose 
acetic  acid  to  be  biu-nt,  it  is  resolved  into  H2O  and  CO.,.  This  reaction 
might  be  explained  on  the  supposition  of  the  molecule  being  CH.,0 
as  vrell  as  0,^^0.2  for  CH2O  +  0  =  CO2  +  HoO.  But  as  already  pointed 
out,  in  the  case  of  the  formation  of  salts,  one  fourth  of  the  hydrogen 
is  replaced  by  K,  or  Na,  or  Ag ;  hence  4  and  not  2  atoms  of  hydrogen 
must  be  present.  As  this  is  the  case,  we  might  represent  the 
formula  of  acetic  acid  thus — (C2H302)H,  that  is,  placing  the 
replaceable  hydrogen  outside.  Again,  in  the  formation  of  chloride 
of  acetyl  by  the  action  of  pentachloride  of  phosphorus,  we  foimd 
that  2  atoms  of  0  existed,  and  that  1  of  these  went  off  in  the  phos- 
phorous compound  POCI3.  We  might  therefore  place  this  0  also 
outside,  and  the  formula  for  acetic  acid  would  become  (C2H30)O.H. 
This  formula  explains  at  once  the  constitution  of  anhydrous  acetic  acid 
(C2H3O) — 0 — (C2H3O).  Again,  in  the  formation  of  marsh  gas  from 
acetic  acid,  we  must  split  uj)  the  carbon  group — thus  (C0.CH3)0H  be- 
comes the  formula.  We  have  thus  seen  that  there  may  be  foiu:  ways  of 
representing  the  composition  of  acetic  acid  according  to  the  \deAv 
necessary  to  account  for  a  given  reaction — (1)  C0H3O2;  (2)  (C^HgOo)!!  ; 
(3)  (C2H30)OH;  and  (4)  (C0.CH3)0H.  This  s'hoVs  very  clearly  both 
how  much  and  how  little  is  indicated  by  the  chemical  formula  of  an 
organic  substance.  Sometimes  an  apparently  anomalous  case  occurs  that 
is  puzzling  to  the  chemist.  For  example,  acetone  is  formed  by  the  dis- 
tillation of  acetate  of  baryta,  and  it  is  found  that  three  fourths  of  the 
carbon  pass  into  acetone.  Hence  Cg  would  not  be  sufficient  and  C^  is 
the  necessary  number  of  atoms.  This  would  make  C^HgO^  the  formula 
of  acetic  acid,  contrary  to  all  the  other  observations  and  inferences. 
But  it  is  more  likely  that  in  the  process  2  molecules  of  acetic  acid  are 
involved,  that  is — 

S:i;&ba}=Hco3+cAo. 

The  two  ba  =  1  Ba,  and  this  suggests  of  course  that  two  molecules  of 
acetic  acid  are  united  to  Ba. 

These  are  the  general  considerations  that  guide  the  chemist  in  con- 
structing formulae.  It  can  hardly  be  too  strongly  stated  that  when 
we  speak  of  the  chemical  constitution  of  a  substance  we  refer  more 


54  THE  CHEMISTRY  OF  THE  BODY. 

to  the  formula  representing  it  than  to  the  real  molecular  stnicture  of 
the  body  itself. 

The  follo^\•ing  ijuotatiou  from  Schorlcmmer  gives  succinctly  some  of 
the  leading  properties  of  the  carbon  compounds  (Schorlemmer,  Chemistry 
t>f  Carbon  Compounds,  p.  44). 

"Most  carbon  compounds  are  colourless  when  in  the  pure  state;  but  there 
exist  also  a  great  number  having  characteristic  colo\irs,  and  many  of  these  are  used 
as  dye  stuffs  or  for  the  preparation  of  pigments,  such  as  indigo,  the  colours  of 
madder-root,  cochineal,  aniline  colours,  etc.  It  appears  that  the  colour  of  these 
bodies  depends  on  their  chemical  constitution. 

Odour  and  Taste.  The  odours  of  volatile  carbon  compounds  vary  very  much, 
as  the  following  examples  show  : — Spirits  of  wine,  ether,  acetic  ether,  acetic  acid, 
chloroform,  camphor,  oil  of  cloves,  etc.  Compounds  having  a  similar  constitution 
often  possess  a  similar  smell.  Thus  the  marsh  gas  hj'di-ocarbons  all  possess  a  faint 
smell  of  flowers,  which  is  more  or  less  perceptible  according  to  the  volatility  of  the 
body.  The  compound  ethers  of  the  fatty  acids  smell  like  various  kinds  of  fruits, 
and  are  on  that  account  used  bj-  confectioners  and  perfumers.  Most  sulphur  com- 
pounds, in  which  this  element  is  not  combined  with  oxygen,  are  characterized  by 
their  disagreeable  odour,  and  many  chlorides  have  a  smell  similar  to  that  of  chloro- 
form. Relations  between  odour  and  chemical  constitution  certainly  exist ;  but 
only  a  few  such  are  known.  Thus  the  amines  or  compound  ammonias  have  an 
odour  resembling  that  of  ammonia,  and  many  aldehydes,  compounds  which  readily 
absorb  oxygen  from  the  air,  have  a  pecialiar  suffocating  smell. 

The  taste  of  carbon  compounds  is  equally  as  varying  as  their  odour  ;  we  find  here 
also  that  analogous  constitution  produces  a  similar  taste,  and  the  alkaloids,  as 
quinine,  strj'chnine,  etc.,  have  an  intensely  bitter  taste,  whilst  the  taste  of  the 
alcohols  of  polygenic  radicals,  as  glycerine,  mannite,  and  siigar,  is  pleasantlj'  sweet. 
Solubility.  A  great  number  of  carbon  compounds  are  soluble  in  water,  others 
only  in  alcohol,  ether,  acetic  acid,  benzine,  etc.  These  different  solvents  are  made 
use  of  in  separating  and  purifying  them.  In  homologous  series  the  first  members 
are  generallj^  more  soluble  in  water  than  the  higher  ones.  Thus  in  the  series  of 
the  alcohols  and  fatty  acids,  the  lower  members  are  miscible  with  water  in  all  pro- 
portions, whilst  those  following  next  dissolve  only  in  certain  proportions,  and  the 
highest  are  insoluble  in  water.  All  hydrocarbons  are  either  very  sparingly' 
soluble  or  quite  insoluble  in  water  ;  by  replacing  in  them  a  part  of  the  hydrogen 
by  hydroxyl  or  oxygen,  compounds  are  formed  which  are  more  soluble,  generally 
in  proportion  to  the  more  oxygen  they  contain.  Thus  butyl,  C4H10,  is  almost  in- 
soluble in  water  ;  butyl  alcohol,  C4Hc,(0H)o,  readily  soluble  ;  and  butylene  alcohol, 
C4Hg(0H)j,  mixes  with  water  in  all  proportions.  Succinic  acid,  C^HgOj,  is  more 
soluble  than  butyric  acid,  C^HgOn ;  and  malic  acid,  C^HgOg,  is  very  deliquescent." 

It  remains  now  to  give  in  this  chapter  a  classification  of  the  organic 
compounds  met  Anth  in  the  body.  Two  classifications  might  be  given 
— the  one  based  on  chemical,  the  other  on  physiological  considera- 
tions. Thus,  one  might  classify  the  substances  under  the  headings  of 
the  various  series  of  hydrocarbons,  but  as  not  a  few  of  the  substances 


CHEMICAL  CONSTITUTION  OF  ORGANIC  CONSTITUENTS.    55 

of  interest  to  physiologists  cannot  yet  have  their  place  accurately  fixed,  I 
prefer  to  give  a  physiological  classification — that  is,  one  in  which  they 
can  be  grouped  according  to  the  r6le  they  perform  in  the  general 
economy. 

I.   THE  NITROGENOUS  include— 

I.  THE  PROTEIDS,  OR  ALBUMINOIDS.     No  formula  can  be  given. 

A.  Tkue  Albumins  : 

1.  Albumins— {I)  Serum  albumin  (blood),  and  (2)  egg  albumin  (white 

of  egg). 

2.  Globulins— {!)  Vitellin  (yolk  of  egg),  (2)  myosin  (muscle),  (3)  para- 

globulin  (blood),  and  (4)  fibrinogen  (blood). 
.S.  Fibrin  (blood  clot). 

4.  Proteim—(l)  Casein  (milk),    (2)    alkali  albumin,  and  (3)  syntonin 

(muscle). 

5.  Peptones— (I)  Albumin  peptones,  (2)  gelatin  peptones  (both  digestive 

products). 

6.  Crystallizahle  Alhuminoids—(\)    Hfemoglobin   (colouring   matter  of 

blood),  (2)  Vitellin  plaques  (?). 

7.  Soluble  Ferments— {\)  Ptyaliu  (saliva),  (2)  Pepsin  (gastric  juice),  (3) 

Pancreatin  (pancreatic  Juice),  (4)  Tripsin  (pancreatic  juice),  (5) 
Inversive  ferment  (saliva  ?),  (6)  Rennet  (stomach  of  calf),  (7)  Lactic 
ferment  (intestines),  (8)  Steatolytic  ferment  (pancreas),  (9)  Blood 
ferment  (blood). 

B.  Albuminous  Derwatives  : 

1.  Obtained  by  change  of  physical  conditions  or  by  chemical  action 

from  tissues— (1)  Paralbumin  (cysts),  (2)  Colloid  matter  (diseased 
liver,  etc.),  (3)  Amyloid  matter  (diseased  liver,  kidney,  etc.),  (4) 
Mucin  (mucus),  (5)  Nuclein  (nuclei  of  cells),  (6)  Spermatin  (semen). 

2.  Developed  in   tissues   and   obtained  by  boiling,  etc. — (1)  Collagen 

(yielding  gelatin),  (2)  Chondrigen  (yielding  chondrin),  (3)  Elastin 
(from  elastic  tissue),  (4)  Keratin  (from  epidermis,  etc. ). 

II.  FATTY  NITROGENOUS  MATTERS- 

1.  Phosphoglyceric  acid,  CsHgPOg,  nervous  matter. 

2.  Cholin,  or  neurin,  CgHigNO^,  bile,  etc. 

3.  Lecithin,  C44HgoNPOg,  in  nervous  tissues,  blood  corpuscles,  yolk  of 

egg,  etc. 

4.  Cerebrin,  CJ9H33NO3,  in  nervous  tissues. 

III.  AMINES— 

1.  Urea,  CH4N2O,  urine,  etc. 

2.  Oxaluric  acid,  C3H4N2O4,  urine. 

3.  Allantoin,  C4H6N4O3,  embryonic  fluids. 

IV.  AMIDES— 

1.  Glycocolle,  or  glycin,  C0H5NO2,  bile,  etc. 

2.  Leucin,  CgHjgNOg,  pancreas,  spleen,  intestinal  canal,  etc. 

3.  Tyrosin,  C9H11NO3,  pancreas,  intestinal  canal,  etc. 


56  THE  CHEMISTRY  OF  THE  BODY. 

4.  Creatin,  C4HgN302,  muscles,  etc. 

5.  Creatiniu,  C4H7N3O,  uiine,  etc. 

6.  Tauiiii,  C0H7NSO3,  muscles,  lungs,  f;uces. 

7.  Oystin,  C3H7NSO0,  urine,  etc. 

8.  Sarcosin,  C3H7NO2,  muscle. 

V.  NITROGEXOUS  ACIDS— 

1.  Sulphocyanic  acid,  CNHS,  saliva. 

2.  Uric  acid,  C5H4lN'403 — and  its  derivatives,  Parabanic  acid,  C3N2H.2O;;; 

Alloxan,  C4H2iS'._,04 ;  Guanin,  CjHgXaO ;  Sarcin,  or  hypoxan- 
thin,  C5H4N4O  ;  Xanthin,  C3H4N4O2 ;  Carnin,  CVH3N4O3— urine, 
etc. 

3.  Hippuric  acid,  CgHj,N03,  urine. 

4.  Inosinic  acid,  CioH]4N40j],  muscle. 

5.  Cryptophauic  acid,  C^oHjgNoOio.  urine. 

6.  Bile  Acids — (I)  Glycocholic  acid,  C2CH43NO6. 

(2)  Taurocholic  acid,  C.,6H45NSO;. 

(.3)  Cholalic  acid,  C24H40O5,  and  its  derivative,  dyslysin, 

C.24H3s03. 

(4)  Choloidic  acid,  C24H.J8O4. 

VI.  SALTS  formed  by  union  of  organic  acids  and  inorganic  bases.     These 
will  be  discussed  under  the  heads  of  their  respective  acids. 

1.  Hippurate  of  soda,  C9H8NaN03,  urine. 

2.  Hippurate  of  lime,  CgH^CaNOs,  urine. 

3.  Urate  of  soda,  C5H3NaN403,  urine. 

4.  Urate  of  potash,  C5H3KN4O3,  urine. 

5.  Oxalate  of  lime,  C2HCa04,  urine. 

6.  Glycocholate  of  soda,  C26H42NaNOg,  bile. 

7.  Taurocholate  of  soda,  C26H44NaNS07,  bile. 

8.  Sulphocyanide  of  potassium,  CNKS,  saliva. 

9.  Pheuolsulphate  of  potash,  CgHjO.  KSO3,  urine. 

VII.  NITROGENOUS  BODIES  CONTAINING  NO  OXYGEN— 

1.  Trimethylamine,  CgHgN,  urine. 

2.  Naphthylamine,  CjoHgN,  urine,  fa?ces. 

3.  Indol,  CgH-N,  freces,  etc. 

4.  Skatol,  C9H9N,  fceces. 

5.  Pyrrol,  CH3N,  faeces. 

VIII.  PIGMENTS— 

1.  Blood  Pigments:    (1)   Haemoglobin,    no   formula;    (2)    Haematin, 

C34H34N4Fe05 ;  (3)  Haematoidin. 

2.  Bile     Pigments:     (1)     Bilirubin,     C16H18N2O3 ;     (2)     Biliverdin, 

C16HJ8N2O4;  (3)  Choletelin,  C16H18N2O6 ;  (4)  Bilifuscin,  Ci6H2oN204; 
(5)  Biliprasin,  CisH.-,2N206  ;  (6)  HydrobUirubin ,  C32H44N4O7. 

3.  UEiXEPiGiLENTS  :  (1)  Urobilin,  C32H40N4O-;  (2)  Indican,  CsgHgiNOi-. 

4.  Other  Pigments:  (1)  Lutein,  yolk  of  egg,  etc.;  and  (2)  Melanin, 

eye,  etc.  (no  formula). 


CHEMICAL  CONSTITUTION  OF  ORGANIC  CONSTITUENTS.    57 

II.   THE  NON-NITROGENOUS  include— 

I.  ALCOHOLS:  (1)  Ethylic  alcohol,  CgHglOH),  urme,  etc.;  (2)  Cholesterin, 
C2gH440.HoO,  bile,  nervous  tissues,  etc.  ;  (3)  Glycerine,  C3Hg(0H);j, 
intestine,  etc.;  (4)  Phenol,  CgHgO,  faeces,  urine,  etc. 

IL  FATS:  (l)Tristearin,C3H5(O.Ci8H3gO)3;  (2)Tripalmitin,C3Hg(O.Ci6H3iO)3; 
(3)  Triolein,  €3115(0.01811330)3;  (4)  Soaps,  such  as  tristearates,  palmit- 
ates,  and  oleates  of  potash  and  soda. 

III.  CARBOHYDRATES— 

1.  Glucoses,  CgHjoOg,  :  (1)  Dextrose,   (2)  Chondroglucose,  (3)  Levulose, 

(4)  Mannitose,  (5)  Galactose,  and  (6)  Inosite  (muscle  sugar). 

2.  Sucroses,  C^2H220ii  :   Sucrose  (cane  sugar),  (2)  Lactose  (mUk  sugar), 

(3)  Maltose. 

3.  Ainyloses,    (CeHioOg)o :    (1)  Starch,   (2)    Glycogen,   (3)  Dextrin,  (4) 

InuLin,  (5)  Gums,  and  (6)  Cellulose. 

IV.  THE  NON-NITROGENOUS  ACIDS— 

1.  Acetic  Acid  Series,  Cr^^sS^i '•  (1)  Formic  acid,   CHjOg ;    (2)  Acetic 

acid,  C2H4O2 ;  (3)  Propionic  acid,  CgHgO^ ;  (4)  Butyric  acid, 
C4H8O.2 ;  (0)  Valerianic  acid,  CgH^oOo  ;  (6)  Caproic  acid,  CgHijOg ; 
(7)  (Enanthylic  acid,  CjR-^fi^;  (8)  Caprylic  acid,  C^B-^^0„;  (9) 
Pelargonic  acid,  CgHjgOo ;  (10)  Capric  acid,  CjoH^oOg ;  (11)  Lauro- 
stearic  acid,  C12H24O2 ;  (12)  Myristic  acid,  C14H08O2 ;  (13)  Palmitic 
acid,  CigH3202 ;  (14)  Margaric  acid,  C17H34O2  ;  (15)  Stearic  acid, 
CasiiseOa- 

2.  Glycollic  Acid  Series,    CnHsnOa :  (1)  Carbonic  acid,  CH2O3 ;  (2)  Gly- 

coUic  acid,  C2H4O3  ;  (3)  Lactic  acid,  C3Hg03 ;  (4)  Oxybutyric  acid, 
C4H8O3 ;  (5)  Oxy  valerianic  acid,  C5H;lo03  ?  (6)  Oxycaproic  acid, 
CSH12O3. 

3.  Oxalic  Acid  Series,  CnH2n-04  :  (1)  Oxalic  acid,  C2H2O4 ;  (2)  Malonic 

acid,  C3H4O4;  (3)  Succinic  acid,  C4Hg04;  (4)  Adipic  acid,  CgHj^o04; 

(5)  Pimelic  acid,  C7H13O4 ;  (6)  Suberic  acid,  CgHi404 ;  (7)  Sebacic 
acid,  C10H18O4. 

4.  Oleic  Acid  Series,  Cn^^--20i:  (1)  Acrylic  acid,  C3H402 ;  (2)  Crotonic 

acid,  CiHgOo ;  (3)  Angelic  acid,  CgHgOo ;  (4)  Oleic  acid,  C18H34O0. 


Chap.  IIL— THE  PROTEIDS  OR  ALBUMINOIDS. 

A.  Chemical  Chaeactees. 

These  organic  compounds  of  complex  chemical  constitution  are  the 
most  important  of  all  proximate  principles,  inasmuch  as  none  of  the 
phenomena  characteristic  of  life  can  occur  without  their  presence. 
They  form  the  substratum  of  all  tissues,  and  especially  are  they 
found  in  protoplasm,  forming  the  chief  mass  of  the  nitrogenous  matter 
of  plants  and  animals.  As  a  type  of  these  substances  we  may  take 
egg  albumin,  a  viscous,  non-crystalline,  colourless,  inodorous,  taste- 
less substance,  which  analysis  shows  to  consist  of  carbon,  hydrogen, 


58  THE  CHEMISTRY  OF  THE  BODY. 

oxygen,  nitrogen,  and  sulphur.  Tlic  name  proteid  {jrpoiTeiov,  })re- 
eminence)  was  first  given  b}^  Mulder  to  a  substance  he  obtained  by  the 
action  of  potash  on  albuminous  matter,  and  he  considered  it  to  be  the 
basis  or  radicle  of  all  albuminous  substances,  with  the  h3q3othetical 
formula  CygHogN^Oig.  It  has  been  shown,  however,  that  no  such  definite 
chemical  compound  exists,  and  that  what  Mulder  oljtained  was  merely 
albuminous  matter  more  or  less  modified.  The  composition  of  the  pro- 
teids,  according  to  Hoppe-Seyler,  varies  between  the  following  numbers — 


C 

H 

N 

S 

0 

From 

51-5 

6-9 

15  "2 

0-3 

20-9 

To 

54-5 

7-3 

17-0 

2-0 

23-5 

In  addition,  they  always  contain  a  small  quantity  of  the  chlorides  and 
phosphates  of  the  alkalies,  however  carefully  they  may  have  been  purified. 
Considerable  difference  of  opinion  still  exists  among  chemists  as  to  the 
constitution  of  these  bodies.  The  view  of  Mulder,  above  alluded  to,  that 
all  the  proteids  contain  the  same  radicle,  protein,  is  now  abandoned. 
Nasse  has  attempted  to  get  an  insight  into  their  molecular  construction 
by  studying  experimentally  the  mode  in  which  the  nitrogen  exists  in 
them.  He  treated  various  proteids  in  the  dried  and  powdered  state 
with  caustic  baryta  for  40  or  50  hours  and  examined  the  products  of 
decomposition.  The  conclusion  arrived  at  is  that  part  of  the  nitrogen 
is  held  fii'mly,  Avhilst  part  can  easily  be  displaced,  shomng  that  it  exists 
in  different  states  of  combination.  Comparing  the  action  of  caustic 
baryta  on  albumin  with  its  action  on  compounds,  the  molecular  structure 
of  which  is  fairly  well  known,  such  as  amines,  amides,  or  leucin,  Nasse 
thinks  that  "  a  definite  quantity  of  the  loosely-combined  nitrogen  of 
proteids  is  combined  as  in  amides ;  another  part  as  the  niti^ogen  in 
creatin  or  the  more  loosely-held  portion  of  the  nitrogen  of  uric  acid ;  and 
most  of  the  remainder  as  in  the  acid  amides  and  the  difficultly  expulsible 
nitrogen  of  creatin  or  sarcosin."  ^ 

More  extended  researches  in  a  similar  direction  have  been  made  by 
Schiitzenberger  who  heated  coagulated  albumin  or  other  proteids  with 
caustic  baryta  for  several  hours.  Ammonia  and  acetic  acid  were  thus 
obtained,  and  a  friable  light  yellow  residue  remained,  to  the  extent  of 
96  per  cent,  of  the  albumin  used.  It  would  appear  in  the  first  instance 
that  the  action  of  the  baryta  caused  a  fixation  of  water  and  a  decom- 
position into  (1)  the  fixed  residue  in  which  a  portion  of  the  nitrogen 
is  firmly  combined ;  (2)  volatile  products,  such  as  pyrrol,  indol,  etc. ; 
(3)  ammonia,    the   nitrogen   of   which    is   about  ^  part   of   the   total 

^  Watt's  Diet,  of  Chemistry,  vol.  vii.  p.  1023.  Nasse's  Experiments — Siudien- 
ilber  die  Elweisshorper.       Pfltiger's  Archives,  vi.  p.  589. 


THE  PROTEIDS  OR  ALBUMINOIDS,  59 

nitrogen  in  the  albumin ;  (4)  carbonic  acid ;  (5)  fatty  acids,  more  especi- 
ally acetic  acid;  and  (6)  oxalic  acid.  The  following  equation  illustrates 
this  decomposition — 

C24oH39oN6g075a3  +  57  HoO  =  C019H431N48O106  +  I6NH3  +  3C.H,04  +  SCO,  + 

Albumin.  Water.         Fixed  residue.      Ammonia.  Oxalic  acid.  Carbonic 

acid. 
4C2H4O2  +  C4H5N. 
Acetic  acid.    Pyrrol. 

The  fixed  residue,  by  the  prolonged  action  of  the  baryta  and  a  high 
temi^erature,  yields  (1)  tyrosin,  CgH^-^NOg;  (2)  amido-acids  of  the  fatty 
series,  such  as  leucin  (amido-caproic  acid),  butalanin  (amido-valerianic 
acid),  alanin  (amido-propionic  acid) ;  (3)  glutamic  and  aspartic  acids ; 
(4)  giutimic  acid;  (5)  tyroleucin;  (6)  leucei'ns,  which  are  combina- 
tions of  leucins  and  tyroleucins;  (7)  acids  of  the  general  formula 
C2iiH2„_iN06;  and  (8)  gluco-proteins,  bodies  of  a  sweetish  taste,  having  the 
formula  CiHouNo04  (n  =  10  or  12).  The  bodies  most  easily  obtained 
were  tyrosin  and  leucin,  the  former  to  the  amount  of  from  2  "3  to  3*5 
per  cent.  The  leucins,  having  the  general  formula  CnHoa+jNOo,  and  the 
leuceins,  having  the  general  formula  CaH.,ii_i]Sr02,  are  derived  from  the 
splitting  up  of  the  gluco-proteins.  The  longer  the  action  of  the  baryta 
is  continued  the  greater  is  the  proportion  of  leucins  and  leuceins 
formed,  but  at  the  beginning  of  the  process,  and  whilst  the  solution  is 
diluted,  gluco-proteids  form  the  chief  part  of  the  fixed  residue.  These 
in  turn  are  split  up  into  leucins  and  leuceins,  and  into  intermediate 
compounds  of  gluco-proteins  with  leucins  and  leuceins.  Thus, 
according  to  Schiitzenberger,  albumin  is  an  amido-derivative,  a  ureide, 
which  by  hydration  splits  up  into  a  large  number  of  amido-derivatives.^ 
The  researches  of  the  chemists  have  been  conducted  of  course  on  dead 
albumin.  But,  as  already  pointed  out,  the  dead  state  is  very  different 
from  the  living,  and  we  must  beAvare  of  drawing  conclusions  as  to  the 
chemical  condition  of  living  matter  from  an  analysis  of  the  substance 
after  death.  This  was  emphasized  so  long  ago  as  1837  by  John 
Fletcher,  a  very  suggestive  writer,  whose  speculative  opinions  are  still 
well  worthy  of  study  j^  but  it  was  not  until  1875  that  the  chemical 
difference  between  living  and  dead  protoplasm  was  again  pressed  on  the 
attention  of  physiologists  by  E.  Pfliiger.-^  Dead  albumin,  more  especially 
in  the  dry  state,  can  be  kept  without  change  for  a  great  length  of  time ; 

^  Schiitzenberger,  Becherches  sur  V Albiimhie  et  les  Matltres  Albuminoldes, 
Bulletin  de  la  Soc.  Chemique,  v.  23  and  24.  Also  Watt's  Bid.  ofChem.  v.  viii. 
p.  1682. 

~  Fletcher,  Budiments  0/ Physiology.     Edinburgh,  1837. 
■'  Pfltiger.     See  his  Archives,  vol.  x.  p.  251. 


60  THE  VHEMISTRY  OF  THE  BODY. 

it  is  indifferent  to  oxygen,  iiiid  it  has  the  character  of  chemical  stability. 
But  when  it  becomes  living  all  those  characters  are  reversed.  It  is  now 
unstable,  readily  decomposing  into  simpler  substances,  and,  as  has  been 
well  said,  "  the  molecule  of  albumin  begins  to  live  by  breathing  oxygen."  ^ 
Pfliiger  supposes  that  Avhen  assimilated  the  nitrogen  of  the  proteid  matter 
passes  from  the  state  of  more  or  less  stable  amides  in  the  dead  condition 
to  the  more  unstable  condition  in  which  it  exists  in  cyanogen  and  its  com- 
pounds. Further,  Pfliiger  showed  that  no  better  proof  could  be  given 
of  the  difference  between  the  constitution  of  the  dead  and  of  the  living 
molecule  of  albumin  than  the  affinity  of  the  living  state  for  oxygen. 
He  introduced  li^^ng  frogs  into  chambers  containing  no  oxygen  and  kept 
at  a  low  temperature,  and  observed  that  all  the  processes  of  life  continued 
for  many  hours,  that  is  to  say  there  Avas  constant  self-oxidation.  By  a 
rearrangement  of  the  atoms  or  groups  of  atoms  of  the  molecule  of 
dead  proteid  matter  it  becomes  alive.  It  has  a  strong  affinity  for 
oxygen,  and  it  may  then  split  up  into  simpler  bodies,  some  of  Avhich  do 
not  exist  among  the  decomposition  products  of  dead  proteid  matter. 
Whether  Pfliiger 's  conjecture,  that  the  constitution  of  living  proteid 
matter  is  that  it  contains  cyanogen  radicles  in  which  the  nitrogen  is 
loosely  combined,  be  true  or  not,  there  can  be  no  doubt  his  mode  of 
vie^ving  the  subject  has  been  of  great  value  to  science. 

Follo"\\ang  in  the  same  direction  are  the  able  researches  of  Loew  and 
Bokorny.^  Approaching  the  subject  from  the  point  of  view  of  chemists 
interested  in  the  chemical  changes  in  the  plant,  they  made  the  remark- 
able discovery  that  liAdng  protoplasm  (or  proteid  matter)  has  the 
property  of  reducing  silver  from  a  weak  alkaline  solution  of  silver 
nitrate,  whilst  dead  proteid  matter  has  no  such  effect.  The  observa- 
tion was  made  ^wiih.  the  protoplasm  of  various  alg^e,  but  the  results 
were  not  so  satisfactory  with  the  protoplasm  of  the  higher  plants,  and 
still  less  so  with  that  of  animal  tissues.  This  is  accounted  for  by 
LoeAV  and  Bokorny  by  the  statement  that  animal  protoplasm  is 
extremely  sensitive  to  even  weak  silver  solutions,  quickly  dying,  and 
that  thus  the  usual  reaction  does  not  occur.  By  careful  experiment  and 
reasoning,  they  show  that  the  efiect  is  not  due  to  anything  in  the 
vegetable  cell  except  protoplasm,  and  they  then  inquire  what  substance 
of  a  chemical  nature  in  the  protoplasm  would  have  such  a  reducing 
effect.  They  come  to  the  conclusion  that  in  the  protoplasm  there  is 
something  of  the  nature  of  an  aldehyde.  They  then  direct  attention 
to  the  formation  of  proteid  matter  in  plants,  shoA^ang  that  these  absorb 

^  Gamgee,  Physiological  Chemistry,  vol.  i.  p.  22. 

-  Oscar  Loew  and  Thomas  Bokorny,  Die  Chemische  Kraftquelle  im  Lthendtii 
Protoplasma.     Munich,  1882. 


THE  PROTEIDS  OR  ALBUMINOIDS.  61 

inorganic  nitrogen-compounds,  such  as  nitrates  and  sulphates  of 
ammonia.  These  are  probably  decomposed  in  the  plant  by  the  action 
of  the  salts  of  organic  acids,  setting  free  nitric  and  sulphuric  acids, 
and  these  in  turn  may  be  further  split  up,  so  as  to  supply  the  nitrogen 
and  sulphur  required  in  the  formation  of  proteids.  Further,  Loew 
and  Bokorny  start  with  formic  aldehyde,  and  by  uniting  it  ■v^^.th 
ammonia  they  produce  a  body  termed  the  aldehyde  of  aspartic 
acid.^  Aspartic  acid,  C^HylSTO^,  is  obtained  by  the  decomposition, 
under  the  action  of  acids  or  alkalies,  of  asparagin,  C^HgN^O,,  a 
substance  of  the  nature  of  an  amide  (the  amide  of  succinamic  acid, 
CHg .  NH2 .  CONH2 .  COOH),  frequently  found  in  leaves  and  in  young 
shoots  kept  in  the  dark.  The  accumulation  of  asparagin  in  young- 
shoots  kept  in  the  dark  is  explained  by  supposing  that  in  these  circum- 
stances some  of  the  proteid  already  in  the  shoot  decomposes,  yielding 
among  other  substances  asparagin,  and  that  this  asparagin  does  not  meet 
Math  the  appropriate  non-nitrogenous  matter  mth  which  it  could  com- 
bine to  form  proteid.  Loew  and  Bokorny  show  the  synthesis  of  a 
proteid  in  the  following  manner — 

NHo .  CH .  COH 

(1)  4CH0H       +       NH3      =  '     I  +-2E.fi. 

CH2 .  COH 

Formic  aldehyde.        Ammonia.  Aspartic  aldehyde. 

Then  by  polymerization  of  the  aspartic  aldehyde,  we  have — 

(NHo.CH.COH  \ 

(2)  3^        "I  ^=CioHi,N304  +  2H.,0. 

/  CHo.COHJ 

By  further  polymerization,  in  the  presence  of  a  sulphur  compound,  we 
have — 

(3)  6(Ci2Hi7N304)  -h  HoS  +  6H2  =  G7.H112N1SSO2.  +  2HoO, 

a  formula  representing  the  composition   of    ordinary  albimiin.      The 
synthesis  may  also  be  illustrated  in  another  manner. 
Kepresenting  the  aldehyde  of  aspartic  acid  thus — 

COH 

I 
CH— NH, 

CH.— COH, 

1  The  weak  point  in  this  theory  is  that  the  aldehyde  of  aspartic  acid  is  unknown 
to  chemists,  but  Loew  and  Bokorny  say  that  it  has  not  been  diligently  looked  for, 
and  that  it  is  no  doubt  unstable  and  evanescent. 


02  THE  CHEMISTRY  OF  THE  BODY. 

we  obtain  hy  coiulciisation,  as  above,  the  product — 

COH 

I 
CH— NH2 

C— COH 

il 
CH 

I 
CH— NH„ 

I 
C— COH 

II 
CH 

I 

CH— NHo 

I 
CH., 

I 
COH 

Then  in  a  manner  similar  to  the  building  up  of  complex  liodies  by 
successive  duplications,  along  with  condensation,  we  have  six  of  the 
above  grouped  as  follows  to  form  proteid  matter — 

CHOH  —  CHOH    CHOH  —  CHOH    CHOH  —  CHOH     [a] 

I  I  I  I  I  I 

CH— NH,    CH— NH,    CH— NH,    CH-NH.,    CH— NH,    CH— NH,      [h] 

I  "I  'I  'I  "I  "I 

C— COH      C— COH      C— COH      C— COH      C-COH       C— COH         (<■.) 

II  II  II  II  II  !l 

CH  CH  CH  CH  CH  CH  (f^) 

I  I  I  I  I  I 

CH-NHo    CH— NHo    CH— NH,    CH— NH,    CH— NH..    CH— NH.,      (e) 

I  ^      i  'I  "I  "I  "I 

C— COH       C— COH       C-COH      C— COH      C— COH       C-COH        ( /) 

II  II  II        '      II  II  :i 

CH  CH  CH  CH  CH  CH  (.7) 

I  I  I  I  I  I 

CH— NHo    CH— NH.,    CH— NH,    CH— NH.,    CH— NH.,    CH— NH.      (A) 

I  "1  "I  'I  '1  "I 

CH,  CH,  CH,  CH..  CH.,  CH.,  (i) 

I     '  I     ■  I     "  I     '  I     '  I     ' 

CH— OH      CH— OH  -  CH— OH      CH— OH—  CH— OH      CH— OH        (/.) 

— >  •  ^— 

The  formula  of  this  product  is  C72H^^4Nj8024,  differing  from  the 
formula  Lieberkiihn  gave  for  albumin,  C.^2Hii2Ni8022>  S,  by  2  atoms  of 
H,  2  of  0,  and  1  of  S.  This  ingenious  formula  also  shows  how,  by 
cleavage  of  the  molecule  of  albumin,  various  bodies  may  be  produced. 
Thus,  a  carbohydrate  might  arise  from  a  and  k ;  from  the  rows  5,  e,  h, 
rich  in  N,  by  taking  up  0,  we  obtain  guanin,  uric  acid,  kreatin : 
lines  g  and  d  constitute  a  benzol  nucleus ;  from  i  a  fatty  acid  group, 
which  by  three-fold  condensation  leads  to  stearic  acid.  All  these 
substances  have  been  obtained  from  proteid  matter,  either  by  the 
chemist  in  the  laboratory,  or  as  the  result  of  physiological  experiment. 


THE  P  ROT  BIDS  OR  ALBUMINOIDS.  63 

Similarly,  by  cleavage  in  the  vertical  direction,  and  the  absorption  of 
water,  leucin,  tyrosin,  and  other  bodies  may  be  produced.  Further, 
Loew  and  Bokorny  attribute  the  remarkable  energy  of  living  proteid 
matter  to  the  fact  of  the  existence  in  it  of  an  aldehyde  group  of  atoms, 
in  which  molecular  movements  are  constantly  taking  place.  Thus, 
representing   any   monatomic    radical    by   R,    we   have   an   aldehyde 

^0 
expressed  by  the  formula,  R C         .     Now,   in  such  a  compound 

two  affinities  are  opposed— (1)  the  0  to  the  H,  and  (2)  the  C  to  each 
of  0  and  H.  A  struggle  occurs  between  the  antagonistic  actions, 
causing  much  atomic  movement,  and  one  may  conceive  the  follo'v\dng 
changes  to  occur  in  rapid  succession — 

(1)  (2)  (3)  (4) 

E. C        ,     R C  ,     R C        ,     R C 

\H  -^  \H  \0H. 

If  the  affinities  in  2  and  4  be  satisfied  by  combining  with  another 
substance,  there  will  then  be  a  state  of  comparative  rest ;  but  a  neigh- 
bouring aldehyde  group  would  prol^ably  impair  the  stability,  and 
again  set  up  molecular  action.     Thus — 

CH— NH,  CH— NH 

I'll 
C— C==0      =     C  —  C— OH. 

!l      \  II         \ 

H  H 

Group  in  active  Group  in  passive 

albumin.  albumin. 

A  striking  fact  in  support  of  Loew  and  Bokorny's  theory  that  active 
proteid  matter  contains  a  chemical  substance  of  the  nature  of  an 
aldehyde  is  that  a  weak  solution  of  hydroxylamine  quickly  kills  pro- 
toplasm, a  result  that  may  be  explained  by  assuming  that  a  compound 
is  at  once  formed  by  the  action  of  hydroxylamine  on  the  aldehyde. 
Thus— 

^  0  H0\  .^X— 0— H 

R_C  +       hJn  =  R— C  +H— 0— H. 

\H  H/  \H 

Aldehyde.        Hydroxylamine.  Aldoxan.  Water. 

Or,  C,H30|       ^      HO 


N  =r  CH3  .  CNHOH,  or  C0H4NHO  +  H2O. 

Acetic  aldehyde.     Hydroxylamine.  Acetic  aldoxan. 


I  have  entered  somewhat  fully  into  these  theoretical  views  regarding 
the  composition  of  proteids  because  it  is  only  by  a  consideration  of  such 
that  we  can  understand  how  it  is  that  when  proteids  are  oxidized  there 
is  the  simultaneous  production  of  fatty  acids,  of  aromatic  compounds. 


G4  THE  CHEMISTRY  OF  THE  BODY. 

and  of  bodies  analogous  to  urea.  Further,  the  consideration  of  the 
complexit}'  and  the  instability  of  the  molecule  leads  the  mind  to  the 
conception  of  certain  forms  of  vital  action  being  due  to  molecular  move- 
ments of  a  chemical  character. 

Let  us  next  examine  some  of  the  more  obvious  chemical  characters  of 
the  proteids.  These  may  be  demonstrated  by  making  a  filtered  solution 
of  egg  albumin  (white  of  egg).  "  Only  certain  of  the  proteids  are 
soluble  in  water,  all  are  soluble  Avith  the  aid  of  heat,  in  concentrated 
acetic  acid,  and  in  solutions  of  caustic  alkalies ;  they  are  insoluble  in 
cold  absolute  alcohol  and  in  ether."  (Gamgee,  op.  cit.)  It  can  be 
readily  sho^vn  that  the  albumin  is  precipitated  (1)  by  the  strong  mineral 
acids ;  (2)  by  acetic  acid  and  ferrocyanide  of  potassium  ;  (3)  by  acetic 
acid  and  a  large  amount  of  a  concentrated  solution  of  any  neutral  salt 
of  the  alkalies  or  alkaline  earths  ;  (4)  by  basic  acetate  of  lead  ;  (5)  by 
mercuric  chloride  ;  (6)  by  tannic  acid ;  and  (7)  by  alcohol.  In  the  pre- 
sence of  free  alkali  they  are  slightly  soluble  in  hot  alcohol.  The  follow- 
ing special  tests  may  then  be  applied — (1)  Boil  and  then  add  a  few 
drops  of  strong  nitric  acid ;  the  precipitate  formed  is  insoluble  in  nitric 
acid.  Serum  and  egg  albumin  solutions  show  opalescence  at  a  tem- 
perature of  from  60°  to  65°  C,  and  coagulation  occurs  from  72°  to  73°  C. 
(Hoppe-Seyler.)  (2)  Add  acetic  acid  and  a  solution  of  ferrocyanide  of 
potassium  ;  a  white  precipitate.  (3)  Acidulate  "VAdth  acetic  acid,  and 
add  a  concentrated  solution  of  sodium  sulphate ;  a  precipitate. 
(4)  MiUon's  reaction.  Dissolve  1  part  by  weight  of  mercuiy  in  2  parts 
of  nitric  acid  of  a  .specific  gra\dty  of  1"42,  and  dilute  each  volume  of 
liquid  Avith  tAvo  A'olumes  of  Avater.  Add  a  feAv  drops  of  this  solution  to 
solution  of  proteid,  and  on  heating,  the  fluid  becomes  of  a  i:)urple-red 
colovur.  (5)  Xantho-protein  reaction.  Add  a  fcAv  drops  of  strong  nitric 
acid ;  boil ;  cool ;  and  then  add  a  few  drops  of  solution  of  ammonia ;  a 
yelloAv  colour  is  produced  if  proteid  matter  is  present.  (6)  PiotroioskVs 
reaction.  Add  a  few  drops  of  a  solution  of  sulphate  of  copper  and  of  a 
solution  of  caustic  soda  or  potash;  heat;  a  violet  colour  results. 
(7)  Adamkieiuicz's  reaction.  Add  excess  of  glacial  acetic  acid  and  then 
concentrated  sulphuric  acid;  a  violet  colour  AAdth  feeble  fluorescence 
is  produced. 

B.  Pha^sical  Characters. 

If  a  solution  of  albumin,  such  as  serum-albumin,  in  serum  of  blood, 
Avhich  also  contains  saline  matters  and  crystalline  organic  bodies,  be 
placed  in  a  dialyzer  (see  Figs.  19  and  20)  in  distilled  water,  it  Avill  be 
found  that  the  crystalline  matters  pass  through  the  parchment  mem- 
brane into  the  Avater,  AA^hilst  the  proteid  matter  remains  in  the  dialyzer. 


THE    PROTEIDS  OR  ALBUMINOIDS, 


65 


Solutions  of  other  proteids  behave  in  a  similar  way,  unless  they  are 
combined  with   saline   matters,   when   a   portion    may   pass   through. 


Fig.  10. — Hoop  Dialyzer,  consisting  of  a  sheet  of  moist 
parchment  paper  stretched  and  tied  over  a  ring  of  gutta- 
percha. 

Proteids  belong  to  the  group  of  colloids,  thus  described  in  the 
classical  researches  of  Thomas  Graham — "  Although  often  largely 
soluble  in  water,  they  are  held  in  solution  by  a  most  feeble  force.     They 


Fig.  20.— Another  form  of  Dialyzer,  in  which 
the  parchment  is  stretched  and  tied  across  the 
wide  end  of  a  bulb. 

appear  singularly  inert  in  the  capacity  of  acids  and  bases,  and  'm  all  the 
ordinary  chemical  relations.     But,  on  the  other  hand,  their  peculiar 
physical  aggregation  with  the  chemical  indifference  referred  to,  appears 
I.  E 


GG  'i'HJ^  CHEMISTRY  OF  THE  BODY. 

to  be  required  in  substances  that  can  interfere  in  the  organic  processes 
of  life.  The  plastic  elements  of  the  animal  l)ody  are  found  in  this  class. 
As  gelatin  appears  to  be  its  type,  it  is  proposed  to  designate  substances 
of  the  class  as  colloids,  and  to  speak  of  their  peculiar  form  of  aggregation 
as  the  colloidal  condition  of  matter.  Opposed  to  the  colloidal  is  the 
crystalline  condition.  Substances  affecting  the  latter  form  will  be 
classed  as  crystalloids.  The  distinction  is  no  doulit  one  of  intimate 
molecular  constitution."  ^ 

Along  -with  other  organic  bodies,  solutions  of  the  proteids  have  the 
l^rojierty  of  rotating  the  plane  of  the  rays  of  polarized  light.  A  general 
knowledge  of  the  principles  on  which  the  optical  properties  of  various 
organic  substances  are  examined  is  required  of  the  physiological  student, 
and  as  the  use  of  the  polariscope  will  be  frequently  referred  to,  I  shall 
here  give  a  brief  account  of  the  nature  of  polarized  light,  and  of  the 
structure  of  a  Polarizing  Apparatus. 

The  nature  of  polarized  light  is  thus  happily  illustrated  by  a  distin- 
guished Avriter  on  Physics — 

' '  Ordinary  light  consists  of  vibrations  taking  place  always  in  planes  at  right 
angles  to  the  direction  of  the  ray,  but  ia  all  directions  in  those  planes.  That  is, 
if  the  ray  travels  along  the  axle  of  a  wheel,  the  vibrations  composing  it  are  all  iu 
the  plane  of  the  wheel,  but  are  executed  along  any  or  all  of  its  spokes.  The  effect 
of  reflecting  light  from  certain  substances,  or  of  passing  it  through  certain  crystalline 
substances,  is  to  cause  all  the  vibrations  to  take  place  in  the  same  direction — 
that  is,  along  one  spoke  of  the  wheel  and  the  spoke  opposite  to  it.  The  light  is 
then  said  to  be  polarized.  Now,  if  the  wheel,  without  being  rotated,  be  slid  along 
the  axle,  the  spoke  along  which  the  vibrations  take  place  will  trace  out  a  plane. 
When  no  rotative  force  is  applied  to  the  polarized  light,  the  vibrations  all  take 
place  in  this  plane,  and  the  light  is  said  to  be  plane  polarized.  If  we  twist  the 
reflector  or  crystal,  which  we  use  as  a  polarizer,  round  the  direction  of  the  ray  as 
an  axis,  we  shall  shift  this  plane  in  the  same  way  as  if  we  cause  the  wheel  to  turn 
on  its  axis  and  so  shift  the  spoke  along  which  the  vibrations  take  place  ;  but  when 
the  wheel  is  slid  along  the  axis,  this  spoke  will  still  trace  out  a  plane — only  that 
plane  will  not  be  the  same  as  before.  That  is,  if  we  turn  the  polarizing  mirror  or 
crystal,  we  turn  the  plane  of  polarization,  but  the  light  still  remains  plane  polar- 
ized. We  cannot  detect  by  the  eye  in  what  plane  light  is  polarized,  or,  indeed, 
whether  or  not  it  is  polarized  at  all.  In  order  to  do  so,  we  have  to  take  advan- 
tage of  the  following  natural  law  :  Transparent  bodies  which  have  the  power  of 
polarizing  light  in  any  given  plane  are  opaque  to  light  already  polarized  in  a  plane 
at  right  angles  to  that  plane."  ...  "  Thus  to  determine  in  what  plane  light 
is  polarized,  we  have  only  to  take  a  crystal  which  has  the  power  of  polarizing  light 
in  a  certain  plane  fixed  with  regard  to  its  axis,  and  to  turn  it  round  till  the  light 

^  See  Young's  edition  of  Graham's  Physical  and  Chemical  Researches,  p.  553. 
The  paper  from  which  quotation  is  made  appeared  in  Phil.  Trans.  1861. 


THE  P  ROTE  IDS  OR  ALBUMINOIDS. 


67 


Fig.  21. 


-Diagram  showing  action 
of  Nicol's  Prism. 


is  extinguished.     We  then  know  that  the  light  is  polarized  in  a  plane  at  right 
angles  to  that  plane  in  the  crystal."  ^ 

Light  is  readily  polarized  by  passing  it  through  an  optical  apparatus,  called  a 
JSHcoVs  Prism.  This  consists  (see  Fig.  21)  of 
two  prisms  of  transparent  calc-spar  or  Iceland 
spar  A  BCD,  CDEF,  cemented  together  with 
Canada  balsam  at  the  faces  CD,  and  the  faces 
AB,  EF,  cut  so  as  to  make  an  angle  of  68°  with 
theedges^ E, BF.  Theincident  ray m?iisdivided 
into  two  rays,  both  of  which  are  polarized ;  the 
one,  no,  termed  the  ordinary  ray,  follows  the 
ordinary  laws  of  refraction,  remaining  always 
in  the  plane  of  incidence  and  having  a  constant 
index  of  refraction  ;  the  other,  ne,  called  the 
extraordinary  ray,  being  polarized  perpendi- 
cularly to  the  principal  section  of  the  crystal, 
has  its  direction  not  confined  to  the  plane  of 
incidence,  "  unless  that  plane  coincides  with  or 
is  perpendicular  to  the  principal  section,  and 
its  index  of  refraction,  excepting  in  the  last- 
mentioned  case,  varying  continually  with  the 
angle  of  incidence. "  -  By  the  Nicol's  prism, 
the  ordinary  ray  suffers  total  reflection  in  the 
direction  oP,  whilst  the  extraordinary  ray  passes  in  the  direction  ef,  and  thence 
issues  as  fo  parallel  to  mn.  An  eye  placed  at  g  would  see  one  image  formed  by 
the  extraordinary  ray  nefg.  Hence  only  one  ray  passes  through  a  Nicol's  prism, 
that  is,  a  ray  polarized  in  a  plane  perpendicular  to  the  principal  section,  or  the 
short  diagonal  of  the  rhomb  ab.  One  Nicol's  prism,  suitably  mounted,  is  termed 
a  polarizer,  because  by  itlight  is  brought  into  a  polarized  state  ;  if  now  another 
Nicol's  prism  be  held  between  the  first  one  and  the  eye,  it  will  be  found  that  no 
light  passes  through  when  this  second  prism  is  so  rotated  as  to  have  its  principal 
section  at  right  angles  to  that  of  the  first,  that  both  are  perfectly  transparent 
when  their  principal  sections  are  parallel,  and  that  light  of  diminished  intensity 
is  transmitted  in  intermediate  positions.  This  second  Nicol's  prism  is  termed 
the  analyzer,  because  by  it  the  state  of  the  light  polarized  by  the  first  Nicol  is 
determined. 

If  now  a  beam  of  light,  polarized  by  a  Nicol's  prism  in  a  horizontal  plane,  be 
passed  through  a  tube  containing  a  solution  of  albumin  or  of  sugar,  its  plane  of 
polarization  on  emergence  will  be  rotated  to  one  side  or  the  other  of  the  hori- 
zontal. To  understand  this,  we  must  conceive  the  case  of  two  rays  of  light  of  the 
same  amplitude  travelling  along  the  same  path,  polarized  so  as  to  be  at  right  angles 
to  each  other,  and  differing  in  phase  by  a  quarter  of  a  wave  length,  then  the 
resultant  wave  would  have  its  molecules  rotating  in  circles  transversely  to  the 
direction  of  the  ray.  This  is  termed  circular  polarization,  and  the  effect  is  the 
same  as  "if  the  ray  were  polarized  in  one  plane,  and  that  plane  were  made  to 
rotate  round  the  direction  of  the  ray  as  an  axis,  making  a  complete  revolution 
during  the  time  of  one  vibration."^    Mr.  Gordon  gives  an  ingenious  mechanical 


^  Gordon,  Physical  Treatise  on  Electricity  and  Magnetism,  vol.  ii.  p.  206. 
2  Watt's  Diet,  of  Chem.  vol.  iii.  p.  6o4.     ^  Ihid.  vol.  iii.  p.  674. 


68  THE  CHEMISTRY  OF  THE  BODY. 

illustration  of  this  state  of  matters  :  ''  Let  us,  as  before,  represent  the  plane  of  polar- 
ization by  the  direction  of  the  spokes  of  a  wheel,  and  let  us  slide  the  wheel  backward 
and  forward  on  the  axis,  and  cause  it  to  rotate  at  the  same  time  so  that  the  spoke 
is  always  in  the  plane  of  polarization  at  the  point  where  the  wheel  is  on  the  axis. 
The  case  of  natural  rotation  will  then  be  illustrated  by  considering  the  tiirning  of 
the  wheel  to  be  produced  by  the  guiding  action  of  a  spiral  or  long  screw  thread 
cut  on  the  axis.  Thus,  as  the  wheel  moves  along,  the  spoke  traces  out  a  twisted 
surface,  while,  when  the  wheel  is  slid  back  again,  the  spoke  comes  back  along  the 
same  surface."^  Further,  the  direction  of  the  movement  of  the  ether  molecules 
from  the  centi-e  of  the  circle,  or  in  other  words,  the  direction  of  the  plane  of  polar- 
ization, may  be  to  the  right,  like  the  movement  of  the  hands  of  a  watch,  or  to  the  left, 
the  revei'se  direction,  and  substances  rotating  to  the  right  are  dextro-rotatory,  whilst 
those  to  the  left  are  hT?vo-rotatory.  This  effect  on  polarized  light  is  due  to  the 
molecules  of  the  body  in  solution,  and  it  follows  that  the  amount  of  rotation  will 
depend  on  the  length  of  the  column  of  the  solution  and  upon  the  strength  of  the 
solution.  As  the  degree  of  rotation  varies  according  to  the  wave  lengths  of  the 
rays  of  the  spectrum,  the  light  chosen  should  be  yellow  rays,  such  as  are  emitted 
from  a  colourless  gas  flame  in  which  common  salt  is  volatilized.  On  these 
principles  instruments  are  constructed  termed  Polarimefers,  or  when  employed  for 
solutions  of  sugar,  Sarrharinteters,  of  which  a  convenient  form,  made  by  Soleil,  is 
shown  in  Fig.  22. 


Fio.  22. — Saocharimetor  of  Soleil. 
Suppose  then,  to  put  the  matter  in  a  simple  form,  that  the  fluid  to  be  examined 
is  placed  in  a  glass  tube  surrounded  by  brass,  and  closed  at  both  ends  with  plate 
glass  discs,  to  fit  watertight,  screw-caps  pressing  firmly  on  the  discs.  The  length 
of  the  column  of  fluid  is  usually  1  decimetre.  The  tube  may  be  placed  on  the 
support  in  the  position  of  the  dotted  line  (Fig.  22),  between  two  Nicol's  prisms 
at  a  and  b.  The  one  Nicol  is  the  polarizer,  the  other  the  analyzer.  Set  the  two 
Nicol's  prisms  so  that  their  principal  sections  are  at  right  angles  and  then,  as 
above  explained,  on  looking  through  the  apparatus  at  a  yellow  light  the  field  will 
be  dark  so  long  as  the  tube  is  not  interposed.  When  the  tube  is  put  in  position 
the  field  is  at  once  lit  up,  and  then  the  analyzing  prism  must  be  rotated  until  the 
light  disappears.  The  angle  through  which  the  analyzer  has  been  turned 
measures  the  rotation  produced  by  the  solution  in  the  tube.  With  this  arrange- 
ment the  difficulty  is  in  determining  when  the  light  disappears,  and  to  obviate 
this  an  appeal  is  made  to  the  sensitiveness  of  the  eye  to  colour.  It  is  well  known 
that  when  a  plate  of  the  uniaxial  crystal  of  quartz,  cut  at  right  angles  to  the  optic 
axis,  is  placed  between  two  Nicol's  prisms  with  their  axes  crossed  (that  is  with 
the  field  dark)  a  series  of  brilliant  colours  appears — red,  yellow,  green,  blue, 
according  to  the  thickness  of  the  quartz  plate.     This  is  because  quartz  exhibits 

^  Gordon,  073.  cif.  p.  208. 


THE  PROTEIDS  OR  ALBUMINOIDS. 


69 


circular  polarization  in  a  striking  Avay.  It  will  also  be  found  by  experiment  with 
different  colours  that  to  cause  the  colour  to  disappear  the  analyzer  must  be  rotated 
through  a  different  angle  for  each  colour,  an  angle  constant  for  a  given  thick- 
ness of  plate  for  each  colovir.  Thus,  with  a  quartz  plate  3  "75  mm.  thick  the  angles 
of  rotation  are  as  follows  : — Medium  red,  56°  "25; 
orange,  71°'25  ;  yellow,  90°  ;  green,  101°'25 ;  blue, 
120°;  indigo,  142°"o  ;  and  violet,  165°,  as  shown  in 
Fig.  23.  Observe,  the  angle  is  least  for  red  and  greatest 
for  violet.  Some  varieties  of  quartz  are  dextro-  whilst 
others  are  Isevo -rotatory,  but  for  a  given  thickness 
of  plate  in  both  cases  the  angle  of  rotation  is  the 
same.  Experiment  has  shown  that  with  a  quartz 
plate  3'75  mm.  thick,  when  the  principal  sections 
of  the  polarizer  and  analyzer  are  parallel,  the  red 
and  violet  rays  are  transmitted  with  only  slightly 
diminished  intensity,  the  resultant  colour  being 
purple,  which  passes  quickly  to  red  or  violet  on 
rotating  the  analyzer.  This  special  tint  (sensitive- 
tint,  transition-tint,  couleur  sensible,  teinte  de 
passage)  is  used  in  optical  arrangements  as  a 
standard  tint  because  it  is  easy  for  the  eye  to 
determine  when  this  tint  has  been  obtained  and 
when  it  disappears. 

Soleil  has  taken  advantage  of  these  facts  in  the  construction  of  the  Sacchari- 
meter,   a  diagram  of  which  is  shown  in  Fig.  24.      The  light  from  a  gas  flame  is 


Fig.  23.— Diagram  showing  the 
angular  rotation  of  a  beam  of 
white  light  (polarized  by  a  Nicol's 
prism  whose  principal  axis  is 
parallel  to  A  A)  caused  by  its  pas- 
sage through  a  quartz  plate  3'7j 
mm.  in  thickness,  r-r'  plane  of 
vibration  of  red,  o-o  of  orange, 
2/-?/' of  yellow,  gr-gr'  of  green,  h-h'oi 
blue,i-i'ofindigo,andr-i;' of  violet. 


u.  r      Q 

e-f§- 


Ellld^]^^ 


r'l.linil^l 


Fig.  24. — Diagram  showing  the  optical  arrangements  in 
Soleil's  Saccharimeter.     For  further  description,  see  text. 

polarized  by  a  Nicol's  prism,  c  {d  m.  Fig.  22) ;  and  it  then  passes  through  a  double 
plate  of  quartz  3-75  mm.  thick  (at  h  in  Fig.  22).  One  half  of  this  plate  is  dextro- 
[d),  whilst  the  other  is  lajvo-rotatory  {g),  as  seen  in  diagram,  <jd.  The  light  passes 
through  the  tube  containing  the  solution,  placed  in  the  position  of  the  dotted  line 
in  Fig.  22,  then  traverses  a  quartz  plate  g,  cut  perpendicularly  to  its  axis,  then 
through  an  arrangement  called  the  compensator  at  r,  then  through  the  analyzer,  a 
Nicol's  prism,  a,  and  lastly  through  a  telescope  L.  The  following  description  of 
the  compensator  and  of  the  general  action  of  the  instrument  is  given  by  the  late 
Mr.  Henry  Watts  in  the  article  "  Light  "  in  Watt's  Dictionary  of  Cheviidry,  vol. 
iii.  p.  674.     (See  Fig.  24.) 

"  RR  is  a  horizontal  section  of  the  compensator,  consisting  of  two  quartz-prisms 
perpendicular  to  the  axis,  and  of  contrary  rotation  to  the  plate  q.  These  prisms 
can  slide  one  over  the  other  horizontally  and  in  contrary  directions,  so  as  to  vary 
the  thickness  which  the  modified  light  has  to  traverse.    They  are  set  in  motion  by 


70  THE  CHEMISTRY  OF  THE  BODY. 

a  toothed  pinion  fixed  to  the  button  (B  in  Fig.  22),  and  acting  on  two  racks 
adapted  to  the  lower  part  of  the  mounting  of  the  prisms.  One  of  these  mountings 
carries  an  ivory  scale  (seen  a  little  to  the  ri^ht  of  a  in  Fig.  22),  represented 
separately  at  E  ;  the  other,  a  vernier,  which  slides  along  the  scale,  and  serves  to 
measure  the  opposite  displacement  of  the  two  prisms.  When  the  zeros  of  the 
scale  and  vernier  coincide  the  two  prisms  are  opposite  to  one  another,  and  their 
thicknesses  are  together  equal  to  that  of  the  plate  q,  the  rotatory  power  of  which 
is  therefore  neutralized  by  them.  The  analyzer  may  then  be  turned  by  means  of 
an  endless  screw  into  such  a  position  that  the  two  halves  of  the  double  quartz 
plate  may  exhibit  the  sensitive  tint.  If  the  tube  containing  the  liquid  be  then  put 
in  its  place,  the  two  halves  gd  will  then  exhibit  veiy  different  colours :  and  to 
restore  them  to  equality  the  compensator  r  must  be  so  adjusted  as  to  produce,  to- 
gether with  the  plate  q,  an  inversion  opposite  to  that  of  the  liquid,  either  by 
increasing  the  thickness  of  the  double  prism,  r,  or  by  diminishing  it,  so  as  to  allow 
the  action  of  the  plate  q  to  predominate.  The  direction  in  which  the  vernier  is 
moved  along  the  rule,  which  is  marked  with  two  series  of  divisions  on  opposite 
sides  of  the  zero-point,  indicates  the  direction  of  the  rotation  exerted  by  the  liquid, 
and  the  displacement  of  the  vernier  gives  the  angle  of  deviation  when  the  thick- 
ness of  quartz  corresponding  to  one  division  of  the  scale  is  known.  These  divisions 
are  usually  made  to  correspond  with  the  tenth  of  a  millimetre  ;  the  vernier  indicates 
a  tenth  of  these  so  that  the  estimation  maybe  made  to  the  hundredth  of  a  millimetre. 
The  half  of  this  quantity  suffices  to  produce  an  appreciable  difference  of  tint  in  the 
two  halves  of  the  double  quartz  plate.  When  either  the  light  or  the  liquid  in  the  tube 
is  coloured,  this  colour,  added  to  that  produced  by  the  polarization,  modifies  the 
sensitive  tint  and  diminishes  the  accuracy  of  the  observation.  To  neutralize  this 
colour,  Soleil  places  at  the  extremity  [d,  Fig.  22)  of  the  instrument  a  doubly- 
refracting  prism,  n  (Fig.  24),  and  a  quartz  plate,  i  (Fig.  24),  fixed  in  a  socket  which 
can  be  turned  round  its  own  plane  by  means  of  a  toothed  wheel  or  pinion  (D  in 
Fig.  22),  worked  by  the  button  (C  in  Fig.  22).  This  plate  is  interposed  between 
the  two  prisms  n  and  c,  the  second  of  which  acts  as  an  analyzer,  and  yields  a 
colour  which  may  be  varied  by  turning  the  prism  n,  so  that  a  position  of  this 
])rism  may  be  found  which  gives  a  tint  capable  of  sensibly  neutralizing  that  of  the 
liquid  or  of  the  light  employed."  ^ 

By  means  of  such  an  instrument  "the  specific  rotatory  power,  "[a],  of  a  solution  of 
any  substance  may  be  determined  in  degrees,  and  the  term  designates  "the 
rotation  of  the  plane  of  polarized  light  produced  by  1  gramme  of  substance 
dissolved  in  1  cubic  centimetre  of  liquid  when  examined  in  a  column  1  deci- 
metre thick."  Let  e  =  the  quantity  of  substance  in  a  imit  weight  of  solution  ; 
/  the  length  of  column  ;   and  a  the  angle  of  rotation,  the  angle  of  rotation  for 

a 
unit  of  length  will  be  -,.      But  as  solution  may  cause  condensation  of  volume, 

divide  the  quantity    ,  by  the  density,  5,  of  the  solution.     The  specific  rotatory 

a 
power  then  =  -,^.     Suppose  a  solution  containing  155  milligrammes  of  cane  sugar 

in  a  gramme  of  water  has  a  specific  gravity  of  1  '06  and  that  the  transition  tint  is 
obtained  by  a  rotation  of  24°  in  a  column  of  fluid  20  centimetres  long,  then  the 
specific  rotatory  power  is 

24 ^^ 

^'^^  ~  -155x20x1 -Of)  ^  ^°''^- 
^  A  description  of  Laurent's  Polarimeter,  a  very  sensitive  instrument,  is  given 


THE  PROTEIDS  OR  ALBUMINOIDS. 


71 


The  specific  rotatory  power  [a]  of  seruin  albumin  is  -  56°,  of  egg 
albumin  -  33°-5  (Hoppe-Seyler)  or  -  38°-08  (Haas),  of  paraglobulin 
-  59°-75  (Haas),  of  sodium  albuminate  -  55°,  of  syntonin,  prepared  by 
the  action  of  dilute  hydrochloric  acid  on  myosin  of  muscle,  -  72°  (Hoppe- 
Seyler),  and  of  casein  dissolved  in  sulphate  of  magnesia  -  80°.  These 
measurements  are  for  yellow  light  near  D  line  of  spectrum,  and  hence 
represented  by  [a]  -q. 

C.  Physiological  Characters. 

Proteid  matters,  such  as  albuminates,  or  substances  related  to  them, 
are  found  in  all  the  tissues  and  fluids.  The  following  table  from 
Gorup-Besanez,  gives  the  proportion  in  1000  parts — 


FLUIDS. 

TISSUES. 

Cerebro-spinal  fluid,    - 

-      0-9 

Spinal  cord, 

-    74-9 

Aqueous  humour, 

-       1-4 

Brain, 

-     86-3 

Liquor  amnii, 

-       7-0 

Liver, 

-  117-4 

Pericardial  fluid, 

-     23-6 

Thymus  of  calf,  - 

-  122-9 

Lymph, 

-     24-6 

Egg,    -        -        .        . 

-  134-3 

Pancreatic  juice, 

-     33-3 

Muscles,      -        -        - 

-  161-8 

Synovial  fluid,     - 

-    39-1 

Middle  coat  of  arteries. 

-  273-3 

Milk,  -         -         -         - 

-     39-4 

Cartilage,    - 

-  301-0 

Chyle, 

-    40-9 

Bone,  .         -         -         - 

-  345-0 

Blood, 

-  195-6 

Crystalline  lens,  - 

-  383  0 

All  are  derived  from  the  vegetable  or  animal  substances  constituting 
food.  Ultimate  analysis  shows  a  great  resemblance  between  animal 
and  vegetable  proteids,  and  it  may  be  inferred  that  the  proteids  of 
animals  are  only  modifications  of  those  found  in  plants.  A.  Brittner^ 
gives  the  following  analysis — 


Egg  albumin, 

C 

H 

N 

0 

S 

54-00 

16-55 

6-99 

22-82 

1-63 

Blood  albumin,    - 

53-50 

15-60 

7-14 

22-46 

1-.30 

Plant  albumin.    - 

54-98 

15-84 

7-31 

20-65 

1-22 

Blood  fibrin, 

52-40 

18-07 

7-03 

21-29 

1-22 

Plant  fibrin,  - 

53-82 

16-04 

7-30 

21-80 

1-04 

Animal  casein,    - 

54-67 

15-78 

7-46 

22-97 

1-12 

Plant  casein. 

53-94 

16-47 

7-16 

21-93 

0-50 

As  will  be  afterwards  studied,  proteids  are  converted  by  the  digestive 
process  into  peptones  and  in  this  condition  pass  into  the  blood.  From 
the  blood  they  are  partly  absorbed  by  the  tissues,  becoming  for  a  time 
part  of  the  living  matter,  and  they  may  partly  exist  in  the  blood  in  a 

in  Gamgee's  Physiological  Chemistry,  p.  8  et  seq.  For  full  details  regarding  instru- 
ments of  this  description  see  Landolt's  Handbook  of  the  Polariscope,  1882. 

1  A.  Brittner,  N.  Rep.  Pharm.  xxi.  66-108,  129-150.     Quoted  in  Watt's  Diet,  of 
Ghem.  vol.  viii.  p.  1684. 


Tl 


THE  CHEMISTRY  OF  THE  BODY, 


state  of  combination  with  saline  matters.  The  processes  occurring  in 
the  living  matter  lead  again  to  a  splitting  up  of  the  complex  molecule, 
and  simpler  bodies  are  formed ;  these  again  decompose,  and  after  a  series  of 
descending  steps,  urea,  carbonic  acid,  and  sulphates  become  the  ultimate 
products  eliminated  from  the  body  by  various  channels.  It  is  imi)or- 
tant  to  observe  that  the  product  carrying  off  nearly  the  whole  of  the 
nitrogen  is  urea,  and  it  is  instructive  now  to  compare  the  percentage 
composition  of  proteid  and  urea — 


C                   H 

0 

N 

S 

Proteid,  -       -       -       - 
Urea,      -       -      .      - 

53               7-30 
20               6-6 

23  04 

26-67 

15-53 

46-67 

1-13 

This  table  shows  that  urea  contains  about  three  times  as  much  nitrogen 
as  proteid  matter,  or  100  grms.  of  urea  contain  as  much  nitrogen  as  300 
grms.  of  proteid.     (Foster.) 

Chap.  IV. —CHARACTERS  OF  THE  SPECIAL  PROTEIDS. 
A.  True  Albumins. 

1.  The  Albumins. — Their  general  characters  are  thus  summed  u}): — 
They  all  contain  nitrogen  and  sulphur ;  their  chemical  constitution  oscil- 
lates round  the  f ollo^-ing :  Cj^H-jST^gOg^S.  AmorjAous,  soluble  in  water 
and  various  acids,  usually  soluble  in  alkalies ;  almost  insoluble  in  alcohol 
and  ether.  Aqueous  solutions  are  neutral.  They  yield  in  flame  an  odour 
of  burned  horn,  giving  off  ammoniacal  products,  and  leaving  a  residue  of 
ash  which  consists  mostly  of  phosphate  of  lime.  Left  to  themselves 
they  decompose  very  easily.  Calcined  with  potash  orboiled Avith sulphuric 
acid,  they  furnish  leucin  and  tyrosin.  Concentrated  nitric  acid,  when 
hot,  transforms  them  into  a  yellow  body,  xanthoproteic  acid.  Treated  by 
acids,  alkalies,  or  after  putrid  decomposition,  they  yield  the  folloAving 
products  :  oily  volatile  acids,  oxalic,  acetic,  formic,  valerianic,  fumaric, 
and  asparagic  acids;  leucin,  tyrosin,  ammonia,  etc.  By  oxidation  of 
albumin,  formic,  acetic,  propionic,  butyric,  valeric,  capric,  and  benzoic 
acids,  and  the  aldehydes  of  these  acids,  various  organic  volatile  bases, 
acetonitrile,  valeronitrile,  and  propionitrile  may  be  obtained. 

(1)  Serum  Alhumin. — When  dried,  it  is  a  clear  yellow,  transparent, 
vitreous  substance,  soluble  in  water ;  the  solution  is  somewhat  opales- 
cent, and  lightly  fluorescent.  At  70°  C.  heat  coagulates  it  if  the  solution 
is  not  very  alkaline.  In  this  coagulation  there  always  remains  a  small 
quantity  of  alkaline  albuminate,  and  the  liquid  may  even  become  alka- 
line.    According  to  Mathieu  and  Urbain,  the  carbonic  acid  dissolved  in 


CHARACTERS  OF  THE  SPECIAL  PROTEIDS.  73 

the  albumin  combines  with  it  under  the  influence  of  the  heat  and  is  the 
cause  of  the  coagulation.  Solutions  of  albumin,  deprived  of  carl^onic 
acid  by  being  placed  in  a  vacuum,  become  incoagulable.  Alcohol  precijj- 
itates  it  from  its  solutions ;  carbonic,  acetic,  tartaric,  phosphoric  acids 
do  not  precipitate  it ;  the  concentrated  acids  precipitate  it,  especially 
nitric,  metaphosphoric,  picric,  carbolic,  and  tannic  acids.  The  alkalies 
transform  it  into  basic  albumin.  It  dissolves  in  concentrated  nitric 
acid ;  most  of  the  metallic  salts  precipitate  it.  After  being  deprived  of 
all  its  salts  by  the  dialyzer,  it  is  not  precipitated  by  heat  or  alcohol,  but 
is  precipitated  by  ether.  Deprived  of  its  volatile  salts,  and  especially  of 
the  carbonate  of  ammonia  by  the  absolute  vacuum,  it  is  transformed  into 
a  matter  said  to  be  identical  with  fibrinogen  and  fibrinoplastic  substances. 
Kept  several  days  in  the  vacuum,  at  a  temperature  of  40"  to  60°  C,  it 
abandons  considerable  quantities  of  gas,  consisting  mostly  of  carbonic 
acid,  hydrogen,  and  a  small  quantity  of  nitrogen.  It  de\dates  polarized 
light  to  the  left. 

(2)  Egg  Albumin. — When  dried  in  air  it  forms  a  pale,  yellowish, 
translucent  mass,  easily  triturated  to  a  white  powder.  It  does  not 
dissolve  readily  in  water,  but  the  presence  of  any  alkaline  salt  causes 
it  to  dissolve  easily.  An  aqueous  solution  deviates  the  plane  of 
polarized  light  to  the  left.  A  solution  on  being  heated  becomes 
opalescent  at  60°  C,  begins  to  deposit  a  coagulum  at  60°  to  63°  C,  and  at 
a  temperature  a  little  higher  the  whole  mass  coagulates.  It  is  in- 
soluble in  alcohol  or  ether.  Ether  only  coagulates  a  portion  of 
albumin  in  solution.  The  reactions  with  acids  are  the  same  as  those  of 
serum  albumin.  The  chief  distinction  between  serum  albumin  and 
egg  albumin  is  that  ether  does  not  precipitate  the  former  whilst  it 
precipitates  the  latter. 

(3)  Vegetable  Albumin. — In  the  juices  of  many  plants  a  substance 
exists  having  similar  properties  to  the  albumins  above  described.  It 
coagulates  when  heated  from  65°  to  70°  C,  and  it  gives  the  same  reactions 
as  animal  albumin  with  the  acids,  etc.  Existing  in  neutral  or  acid 
fluids  in  the  plant,  it  is  found  in  the  juice  of  carrots,  turnips,  cabbages, 
the  green  stems  of  peas,  potatoes,  and  in  wheat  flour ;  it  is  also  found  in 
oleaginous  seeds.  It  difi"ers  from  legumin  (vegetable  casein)  by  being 
precipitated  by  heat,  but  not  by  acetic  acid. 

2.  The  Globulins. — Albuminoid  matters  insoluble  in  water,  soluble 
in  a  strong  solution  of  chloride  of  sodium ;  their  solution  coagulated  by 
heat ;  changed  into  syntonin  by  very  dilute  hydrochloric  acid,  and  into 
alkali-albumins  by  the  action  of  alkalies.     They  include — 

(1)  Fitellin,  a  substance  existing  in  yolk  of  egg ;  it  is  not  precipitated 
from  its  solutions  by  common  salt.     Its  solutions  coagulate  at  70°  to 


74  THE  CHEMISTRY  OF  THE  BODY. 

75°  C.       It  is  changed  into  syntonin  hy  the  action  of  dilute  hydro- 
chloric acid. 

(2)  Myosin. — This  substance  exists  in  a  fluid  condition  in  living 
muscle,  and,  by  its  spontaneous  coagulation  after  death,  the  condition 
called  cadaveric  rigidity  is  produced.  It  may  be  obtained  by  pressure 
from  the  muscles  of  a  frog  recently  killed.  It  is  transformed  by  Avcak 
acids  into  syntonin ;  its  saline  solution  is  coagulated  by  heat  like 
albumin  at  55°  to  60°  C. ;  alcohol  precipitates  it.  It  is  readily  soluble 
in  a  weak  solution  of  common  salt,  and  it  is  precipitated  from  such  a 
solution  on  saturation  ^dth  common  salt. 

(3)  Paraglohilin. — Serum-globulin  or  fibrinoplastic  substance  :  a  sub- 
stance existing  in  the  blood,  soluble  in  weak  solutions  of  common  salt ; 
from  weak  alkaline  solutions  it  is  precipitated  by  a  small  quantity  of 
common  salt ;  "  a  further  addition  of  this  body  leads  to  re-solution  of 
the  precipitate,  which  is  thrown  down  again  when  the  amount  of  sodium 
chloride  in  solution  exceeds  20  per  cent."  (Gamgee,  op.  cit.)  It  is  pre- 
cipitated completely  by  magnesium  sulphate.  "The  temperature  of 
coagulation  varies  (according  to  amount  of  salts  present  and  mode  of 
heating)  between  68°  and  SO"",  on  an  average,  75°  C."     (Gamgee.) 

(4)  Fibrinogen,  a  substance  also  existing  in  the  blood.  It  is  soluble 
in  water  and  in  Aveak  solution  of  sodium  chloride.  It  is  "precipitated 
from  them  completely  by  the  addition  of  sodium  chloride  when  this 
amounts  to  12  to  16  per  cent."  (Gamgee.)  Carbonic  acid  gives  a 
precipitate  which  forms  ^vith  difficulty;  it  is  also  precipitated  by  a 
mixture  of  3  parts  of  alcohol  to  1  part  of  ether,  and  by  sulphate 
of  copper  ;  the  precipitate  is  insoluble  in  an  excess  of  the  reagent.  The 
temperature  of  coagulation  is  56°  C. 

3.  Fibrin. — This  is  an  albuminous  body  formed  during  the  coagula- 
tion of  blood,  chyle,  or  lymph.  It  is  produced,  according  to  one  theory, 
by  the  combination  of  the  two  soluble  albuminoids  above  described, 
fibrinogen  and  fibrinoplastic  substance.  Fibrinogen  is  found  in  all  fluids 
which  may  transude  from  the  blood  into  the  tissues,  in  the  fluid  part 
of  the  blood  itself,  called  the  liquor  sanguinis,  in  lymph  and  in  chyle  : 
whilst  fibrinoplastic  substance  exists  in  the  blood  corpuscles  and  in 
small  quantity  in  the  liquor  sanguinis.  The  conditions  favouring  the 
union  of  these  two  substances  to  form  fibrin  will  be  described  in  treat- 
ing of  the  coagulation  of  the  blood. 

AVhen  obtained  by  washing  blood  clot,  it  consists  of  white  amorphous 
filaments ;  insoluble  in  water,  alcohol,  and  mineral  acids,  it  swells  in 
weak  acids  and  in  solutions  of  alkaline  salts ;  it  is  solul^le  in  weak 
acids  (acetic,  lactic,  and  phosphoric  acids),  potash,  solutions  of  alkaline 
salts,  -^-^  %  solution  of  chloride  of  sodium ;  f  errocyanide  of  potassium 


'      CHARACTERS  OF  THE  SPECIAL  PROTEIDS.  75 

precipitates  it  from  its  acid,  and  acetic  acids  from  its  alkaline,  solutions. 
"  When  heated  for  many  hours  at  40°  C.  in  dilute  hydrochloric  acid  it 
dissolves,  and  the  solution  contains  acid  albumin."  (Gamgee.)  Fibrin 
decomposes  ozone,  evolving  oxygen  without  seeming  to  suffer  change. 
With  ozone  and  a  few  drops  of  tincture  of  guaiacum,  it  gives  a  blue 
colour. 

4.  The  Proteins  or  Derived  Albumins. — These  are  proteid 
bodies,  insoluble  in  pure  water  and  in  solutions  of  common  salt,  but  are 
readily  soluble  in  dilute  hydrochloric  acid  and  in  dilute  alkalies.  They 
are  not  coagulated  by  heat.     The  proteins  include — 

(1)  Casein. — This  substance  is  coagulated  from  milk  by  heat  with  the 
addition  of  an  acid,  and  by  rennet.  If  any  albuminous  substance  be 
treated  with  an  alkali,  and  if  the  solution  be  neutralized  by  acetic  acid, 
a  substance  chemically  identical  with  casein  is  obtained.  Leguviin, 
found  in  the  grains  of  leguminous  plants,  is  identical  with  casein.  It  is 
insoluble  in  water,  and  soluble  in  waters  lightly  alkalinized.  Its  solution 
is  not  coagulated  by  heat;  it  is  soluble  in  hydrochloric  acid,  less  so  in  acetic 
acid.  Its  solutions  are  precipitated  by  alcohol,  sulphate  of  magnesia, 
chloride  of  calcium,  and  metallic  salts.  When  heated  with  a  strong 
solution  of  caustic  potash,  potassium  sulphide  is  formed.  (Gamgee.)  By 
lengthened  boiling  with  water,  it  gives  lactic  acid  and  creatinin. 

(2)  Alkali  Albumin. — This  is  a  substance  obtained  by  the  action  of 
dilute  alkalies  upon  the  proteids.  In  the  presence  of  alkaline  phosphates 
its  solutions  are  not  precipitated  by  neutralization ;  thus  it  is  distin- 
guished from  acid  albumin  or  syntonin.  When  heated  with  a  strong 
solution  of  caustic  potash,  potassium  sulphide  is  not  formed,  thus  diifering 
from  casein,  to  which  it  is  very  closely  related.     (Gamgee.) 

(3)  Acid  Albumin  or  Syntonin. — This  substance  is  obtained  by  the. 
action  of  dilute  acids,  especially  hydrochloric  acid,  on  proteids  in  solu- 
tion, and  by  the  action  of  strong  hydrochloric  acid  on  solid  proteids. 
It  is  also  the  first  product  of  digestion  in  the  stomach.  It  is  distin- 
guished from  basic  albumin,  because  its  solution  in  weak  acids  and 
alkaline  carbonates  is  precipitated  by  neutralization  (even  in  presence  of 
alkaline  phosphates).  It  has  two  other  principal  tests  :  (1)  its  solution 
in  lime  water  is  partly  coagulated  by  heat ;  (2)  the  same  solution  gives 
a  precipitate,  while  hot,  with  chloride  of  calcium,  sulphate  of  magnesia, 
and  chloride  of  sodium. 

5.  The  Peptones. — These  are  products  of  the  digestive  process, 
and  they  are  distinguished  by  the  following  characters : — They  are  very 
soluble  in  water,  insoluble  in  absolute  alcohol  and  ether,  but  alcohol 
precipitates  them  with  difiiculty  from  an  aqueous  solution ;  heat  does 
not  coagulate  them;   they  are  neither  precipitated  by  acids  nor  by 


76  THE  CHEMISTRY  OF  THE  BODY. 

alkalies,  but  they  are  precipitated  by  bichloride  of  mercury,  or  acetate 
of  lead,  or  ammonia ;  ferrocyanide  of  potassium,  and  acetic  acid  throw 
down  a  px-ecipitate.  They  are  pi'ccii)itated  by  ;i  large  excess  of  u])solute 
alcohol  and  by  tannic  acid.  "  In  the  presence  of  much  caustic  potash  or 
soda,  a  trace  of  a  solution  of  copper  sulphate  produces  a  beautiful  rose 
colour."  (Gamgee.)  They  are  very  diffusible.  They  rotate  to  the  left 
the  plane  of  a  ray  of  polarized  light. 

6.  Crystallizable  Albuminoids.— These  are  (1)  ha^noglobin,  the 
colouring  matter  of  the  blood,  which  will  be  described  in  treating  of 
blood,  and  (2)  vitellin  plaques,  a  peculiar  albuminoid  substance  found 
in  the  yolk  of  the  eggs  of  fishes,  and  said  to  resemble  aleuron  grains  in 
plants. 

7.  Soluble  Ferments. — As  will  be  seen  in  treating  of  fermentation, 
soluble  ferments  are  albuminoid  or  proteid  matter  in  a  peculiar  mole- 
cular condition. 

B.  Albuminous  Derivatives. 

The  albuminous  derivatives  consist  of  two  groups  :  (1)  those  arising 
from  proteids  in  consequence  of  chemical  transformations  ;  and  (2)  those 
arising  from  physical  changes  or  from  the  changes  happening  in  the 
development  of  tissue. 

1.  Albuminous  Derivatives  Chemically  produced.— These  an; 
substances  closely  related  to  those  just  described.  Among  them,  in  addi- 
tion to  certain  substances  found  in  diseased  tissues  we  have  the  intercel- 
lular substance  found  in  bone  and  connective  tissue,  known  as  coUagoi, 
which  yields  gelatin  on  boiling.  Cartilage  supplies  an  analogous  body 
by  prolonged  boiling,  called  chondrin.  In  like  manner,  elastic  tissues 
yield  elastin;  and  epithelium,  hair,  nail,  and  epidermis  yield  JcemfAv, 
which  is  remarkable  for  its  richness  in  sulphur.  Analyses  of  the 
albuminous  derivatives  show  that  gelatin  and  chondrin  are  a  little 
richer  in  oxygen  and  a  little  poorer  in  carbon  than  albuminous  bodies, 
whilst  elastin  contains,  on  the  contrary,  more  carbon  and  less  oxygen. 
Gelatin  is  not  precipitated  by  any  acid  except  tannic  acid,  while 
chondrin  is  precipitated  by  nearly  all  acids.  Both  are  soluble  in  water. 
Keratin  is  not  dissolved  by  boiling  water  or  by  weak  acids,  but  it  is 
dissolved  by  alkalies  and  concentrated  acids.  Elastin  is  dissolved  only 
in  concentrated  alkalies. 

(1)  Paralbumin. — This  is  a  form  of  albumin  often  found  in  ovarian 
cysts  and  in  dropsical  fluids,  and  is  distinguished  from  the  albumin  of 
serum  by  two  characters  :  the  precipitate  obtained  by  alcohol  is  soluble 
in  water ;  and  it  coagulates  incompletely  by  heat. 

(2)  Colloid  matter. — This  is  a  peculiar  gelatinous,  colourless  or  faint- 


CHARACTERS  OF  THE  SPECIAL  PROTEIDS.  77 

yellow,  diill,  or  translucent  substance  resulting  from  a  physiological 
metamorplioses  of  cells.  It  is  often  found  in  the  thyroid  gland,  causing 
a  tumour  called  goitre.  Acetic  acid  causes  it  sometimes  to  swell ;  it  is 
readily  stained  by  carmine ;  it  is  soluble  in  cold  and  hot  water,  for  the 
most  part  not  in  alcohol  or  ether,  but  in  caustic  alkalies.  "  It  has  not 
a  single  positive  character;  it  is  distinguished  from  albumin  by  its 
insolubility  in  acetic  acid,  from  mucus  by  the  extent  of  coagulation  with 
acetic  acid,  and  from  lardaceous  substance  by  the  want  of  colour  vnih 
iodine  and  sulphuric  acid."  (Wagner's  Manual  of  General  Pathology, 
p.  329.)  Colloid  matter  is  held  by  some  to  be  modified  mucin,  whilst 
others  regard  it  as  albumin  which  has  become  insoluble  in  acetic  acid  on 
account  of  the  presence  of  chloride  of  sodium.  It  is  undoubtedly  a 
modified  proteid  substance,  having  most  of  the  chemical  characteristics 
of  proteids. 

(3)  Amyloid  matter,  or  Lardacein. — This  substance  exists  in  a  form  of 
degeneration  of  tissue  (waxy  degeneration),  specially  affecting  the  small 
arteries  and  capillaries,  in  which  the  tissue  acquires  a  dull  lustre  and 
translucent  appearance.  The  parts  become  brownish-red  on  the  addi- 
tion of  diluted  tincture  of  iodine,  whilst  parts  containing  no  amyloid 
matter  are  coloured  yellow.  After  the  addition  of  dilute  or  concentrated 
sulphuric  acid,  the  tissues  assume  a  violet,  rarely  a  blue  hue,  which  may 
remain  unchanged  for  hours  or  weeks,  or  after  a  short  time  may  dis- 
appear. Water  does  not  dissolve  amyloid  matter ;  concentrated  alkalies 
dissolve  it ;  alcohol  and  ether  have  no  effect.  Dilute  acetic  acid  has  no 
effect ;  but  the  strong  acid  may  cause  it  to  swell  up.  It  is  insoluble 
also  in  alkaline  carbonates,  and  it  is  not  acted  on  by  the  gastric  juice  at 
the  temperature  of  the  body.  Kekul6  has  shown  that  amyloid  matter 
contains  cholesterin,  that  it  contains  no  body  similar  to  starch  or  cellu- 
lose as  the  reaction  with  iodine  and  sulphuric  acid  would  lead  one  to 
infer,  and  that  it  is  modified  proteid  matter,  possibly  an  intermediate 
step  between  albuminous  matter  and  fat  and  cholesterin.  In  the 
nervous  centres  (brain  and  cord),  in  the  prostate  gland,  and  in  the  lungs, 
small,  round,  oval,  homogeneous,  or  concentrically  laminated  bodies  are 
occasionally  met  with,  called  corpora  amylacea,  which  become  blue  or 
bluish-grey  by  iodine  alone,  or  quite  blue  after  the  addition  of  sulphuric 
acid.  Some  of  these  bodies,  containing  more  albuminous  substance  than 
others,  become  green,  brown,  or  yellow.  Hot  water  and  caustic  alkalies 
dissolve  them ;  alcohol  and  ether  have  no  effect.  Pathologists  are  of 
opinion  that  the  matter  forming  these  bodies  is  not  the  same  as 
ordinary  amyloid  matter. 

(4)  Muciii. — This  is  a  substance  existing  in  the  mucus  secreted  by 
mucous  membranes ;  it  exists  in  the  connective,  and  more  especially  in 


78 


THE  CHEMISTRY  OF  THE  BODY. 


embryonic  tissues ;  it  is  said  to  form  the  chief  constituent  of  the  bodies 
of  some  invertebrates  {Helix),  and  it  is  found  in  large  amount  in  the 
bile.  It  is  a  glutinous  substance,  soluble  in  water,  in  weak  solutions  of 
the  alkalies  and  alkaline  earths ;  it  is  precipitated  by  alcohol,  by  weak 
acids,  and  acetic  acid  ;  it  is  not  coagulated  by  heat.  Alkaline  or  neutral 
solutions  of  mucin  are  not  precipitated  by  sulphate  of  copper,  bichloride' 
of  mercury,  nitrate  of  silver,  perchloride  of  iron,  etc.  It  is  not  pre- 
cipitated by  acetic  acid  and  ferrocyanide  of  potassium,  nor  by  tannic 
acid,  but  it  is  precipitated  by  acetate  of  lead  from  neutral  or  weak 
alkaline  solutions.  It  contains  C,  H,  N,  0,  but  no  S.  Dr.  Gamgee 
gives  the  following  elementary  analyses  of  mucin  by  various 
observers — 


I. 

From  mucous 
contents  of  a 
cyst.  (Scherer.) 

II. 
From  sub- 
maxillary gland. 
(Obelensky.) 

III. 

From 

Helix  pomo.tia. 

(Elchwald.) 

c.  - 

H.  - 

N.   - 
0.    - 

52-17 

7-01 

12-64 

28-18 

52-31 
7-22 

11-84 
28-63 

48-94 
6-81 
8-50 

35-38 

These  analyses  sho^v  that  it  is  a  substance  related  to  the  proteids. 
It  is  probably  a  product  of  the  differentiation  of  the  protoplasm  of 
certain  animal  cells.     (Gamgee,  op.  cit.) 

(5)  Nuclein. — The  nuclei  of  cells  are  believed  to  contain  an  organic 
body  containing  phosphorus.  It  has  been  isolated  from  pus  cells  in 
sufficient  quantity  for  purposes  of  analysis,  and  appears  as  a  greyish 
mass,  insoluble  in  dilute  hydrochloric  acid  but  soluble  in  a  weak 
solution  of  caustic  soda.  The  analysis  given  by  Miescher  of  the  nuclein 
from  salmon-melt  and  by  Hoppe-Seyler  of  the  nuclein  of  pus  cells 
agree  in  finding  from  2-28  (pus)  to  9-59  (spermatozoa)  per  cent,  of 
phosphorus  present.  Further,  in  the  nuclein  of  yolk  of  egg  Worm- 
Miiller  found  2-2,  2-68,  and  7-9  per  cent,  of  phosphorus.  Gamgee  con- 
siders the  results  of  analyses  so  unsatisfactory  as  to  lead  him  to  deny  the 
existence  of  nuclein  as  "  a  definite  chemical  individual  possessed  of 
constant  composition."     (Gamgee,  op.  cit.  p.  243.) 

(6)  Sperrnatin  is  the  name  given  to  a  substance  found  by  Vauquelin 
in  the  semen  of  a  man  and  by  Kolliker  in  that  of  a  bull  and  stallion. 
It  was  not  coagulated  by  heat,  became  slightly  turbid  on  the  addition  of 
acetic  acid,  whilst  excess  of  the  acid  dissolved  it.  It  was  also  precip- 
itated by  ferrocyanide  of  potassium.  Probably  it  is  not  a  distinct 
substance  but  modified  mucin  or  an  albuminate  of  an  alkali. 


CHARACTERS  OF  THE  SPECIAL  PROTEIDS,  79 

2.  Albuminous  Derivatives  physically  and  histogenetically 
produced. 

(1)  Collagen. — The  organic  basis  of  all  the  connective  tissues,  such  as 
ordinary  white  fibrous  tissue,  tendon,  fascia,  and  the  organic  matter  of 
bone,  consist  of  a  substance  termed  collagen  (KoAAa,  glue)  which  yields 
gelatin  on  boiling.  This  well  known  substance  swells  in  cold  water;  is 
soluble  in  boiling  water,  and  gelatinizes  on  cooling;  it  is  soluble  in  acids 
and  alkalies,  but  is  insoluble  in  alcohol,  ether,  and  chloroform.  Dis- 
solved with  the  aid  of  heat  in  glycerine,  on  cooling,  a  jelly — glycerine- 
jelly — is  formed.  Solutions  of  gelatin  are  precipitated  by  tannin  and 
bichloride  of  mercury;  they  are  not  precipitated  by  solutions  of  acetate 
of  lead,  thus  differing  from  chondrin,  nor  by  acetic  acid  and  ferro- 
cyanide  of  potassium.  The  aqueous  solutions  are  Isevo-rotatory 
of  polarized  light  to  the  extent  at  30°  C.  of  [a]  130°.  (Hoppe-Seyler.) 
Collagen  is  regarded  as  the  anhydride  of  gelatin,  as  Hofmeister 
found  that  by  heating  gelatin  for  some  time  at  130°  C.  it  lost  -755 
per  cent,  of  water  and  became  a  body  identical  with  gelatin.  (Gamgee.) 
Thus— 

C102H151N31O39  +  HoO  =  Ci02Hi49]Sr3iO38. 

Gelatin.  Collagen. 

Prolonged  boiling  causes  gelatin  to  lose  its  property  of  coagulating,  and 
Hofmeister  states  that  the  mixture  then  contains  two  bodies  related  to 
peptones,  to  which  he  gives  the  names  semiglutin  (CgjHggNj^.^Ogs)  and 
hemicollin  (C^^H^oN^^^O^g).  Further,  he  found  that  in  thus  decomposing, 
collagen  combines  with  water.     Thus — 

C102H149K31O38  +  SH^O  -  CgsHgsNi^Oo.,  +  C47H,oNi,Oi9. 
Collagen.  Semiglutin.  Hemicollin. 

Semiglutin  is  precipitated  by  platinum  tetrachloride  Avhilst  hemicollin  is 
not.  Fiu-ther,  by  boiling  in  sulphuric  acid  gelatin  yields,  like  other  pro- 
teids,  ammonia,  leucin,  glycin,  and  perhaps  aspartic  acid;  the  action 
of  caustic  baryta  in  sealed  tubes  is  to  give  "  ammonia,  carbon  dioxide, 
acetic  and  oxalic  acids,  and  a  mixture  of  amido-acids  (containing  glycin 
and  alanin,  amido-butyric  acid,  traces  of  glutamine,  etc.)."  (Gamgee, 
op.  cit.) 

(2)  Chondrigen. — The  basis  of  the  matrix  of  cartilage  is  a  substance, 
chondrigen,  which  yields  chondrin  on  boiling.  If  chondrigen  is  digested 
in  water  at  a  temperature  of  120°  C.  for  several  hours  in  a  Papin's  digester 
it  dissolves  and  the  solution  contains  chondrin.  This  substance  is 
soluble  in  hot  water,  and  gelatinizes  in  the  cold.  It  is  insoluble  in 
alcohol  and  ether  and  in  cold  water.  Its  solutions  are  precipitated  by 
alcohol  as  well  as  by  mineral  acids,  acetic  acids,  alum,  perchloride  of 


80  THE  CHEMISTRY  OF  THE  BODY, 

iron,  acetate  of  lead,  and  nitrate  of  silver;  the  precipitate  is  soluble  in 
an  excess  of  the  reagent.  The  precipitate  by  acetic  acid  is  redissolved 
by  alkaline  salts,  which  disting\iishes  chondrin  from  albuminoid  matters. 
Prolonged  boiling  in  dilute  hydrochloric  or  sulphuric  acids  produces  a 
substance  termed  chondrorjlucose,  -which  is  laevo-rotatory  to  polarized 
light  and  reduces  cupric  salts.  A  similar  substance  is  obtained  from 
mucin  by  boiling  in  dilute  acids.  With  prolonged  boiling  in  dilute 
sulphuric  acid,  chondrin  yields  leucin  but  no  t}TOsin  or  glycocin. 
Morochowitz  denies  the  existence  of  chondrin  as  a  distinct  substance, 
and  regards  it  as  a  mixture  of  gelatin,  mucin,  and  salts.  This  \'iew  is 
supported  by  Gamgee  in  the  follo^^^ng  suggestive  sentence — "If  these 
views  be,  as  the  author  believes,  correct,  all  the  tissues  belonging  to  the 
connective  tissue  group  possess  common  chemical  character  in  that  their 
ground  substance  is  in  all  cases  a  body  transformed  into  gelatin  by  the 
prolonged  action  of  boiling  water;  this  being  mixed  in  greater  or  less 
proportion  Avith  mucin  which,  as  we  have  seen,  undoubtedly  plays  the 
part  in  many  forms  of  connective  tissue  of  a  connecting  or  cementing 
substance."     (Gamgee,  op.  cit.  p.  271.) 

(3)  Elastin. — From  the  Ugamentum  mi-chce  and  wherever  elastic  tissue 
exists,  a  substance  called  elastin  may  be  extracted  by  boiling  first  in 
ether  and  alcohol,  then  for  a  long  time  in  water,  then  in  acetic  acid,  and 
lastly  in  a  concentrated  solution  of  caustic  soda.  When  dried,  it  is  a 
hard,  brittle,  yellowish  substance,  insoluble  in  water,  ammonia,  acetic 
acid,  or  alcohol.  In  solution  it  is  not  precipitated  by  the  mineral  acids, 
but  tannic  acid  precipitates  it  from  a  neutralized  solution.  "  It  is 
soluble  in  boiling  solution  of  caustic  potash,  in  cold  concentrated 
sulphiiric  acid,  and  in  concentrated  nitric  acid."     (Gamgee.) 

(4)  Keratin. — This  substance  is  obtained  bj'  boiling  horn,  hair,  feathers, 
or  cuticle,  in  ether,  alcohol,  Avater,  and  dilute  acids  successiA^ely.  It  is 
insoluble  in  alcohol  and  ether;  it  swells  in  water,  and  still  more  so  in 
acetic  acid.  It  is  soluble  in  solutions  of  caustic  soda  and  potash.  When 
boiled  with  dilute  sulphuric  acid,  keratin  yields  leucin,  tyrosin,  volatile 
fatty  acids,  and  aspartic  acids.  "  Nitric  acid  dissolves  it,  and  oxalic 
acid  is  formed  as  an  ultimate  product."  (Gamgee.)  Keratin  is  remarkable 
for  the  large  proportion  of  sulphur  existing  in  it  in  a  loose  state,  and 
hence  it  yields  sulphuretted  hydrogen  when  heated  in  sealed  glass  tubes 
up  to  150°  to  200°  C.,  and  the  residue  is  first  dissolved  by  boiling  in 
alkalies  and  then  treated  Avith  acetic  acid.  The  amount  of  sulphur 
varies  in  specimens  of  keratin  prepared  from  different  epidermic  tissues. 
Keratin  from  human  hair  contains  sulphur  varying  from  3  to  8 '23  per 
cent.     (Gamgee.) 

The  chemical  composition  of  the  four  albuminous  derivatives — gelatin. 


CHARACTERS  OF  THE  SPECIAL  PROTEIDS. 


81 


chondrin,    elastin,    and    keratin — is    contrasted   with   allDumin   in   the 
foUowinsc  table  ^ — ■ 


Serum 
Albumin. 

Mucin. 

(Obolen- 

sky.) 

Gelatin,     i  Choudrin. 
(Hof-          (Schiitzen- 
meister.)    1     berger.) 

Elastin. 
(Mulder.) 

Keratin. 
(Mulder.) 

c.  -     - 

H.  -      - 

N.  -      - 
0.  -      - 

S.   -      - 

52-7 

6-9 

15-4 

20-9 
0-8 

52-31 

7-32 

11-84 

28-63 

50-75 

6-47 

17-86 

24-92 

doubtful. 

50-16 

6-58 
14-18 
29-18 
doabtful. 

55-47 

7-54 

16-09 

20-90 

51-00 

6-94 

17-51 

21-75 

2-80 

The  following  table- contrasts  the  chief  reactions  of  gelatin,  chondrin, 
and  mucin -^ — 


Gelatin. 

Chondrin. 

Mucin. 

Acetic  acid. 

No  precipitate 

Precipitate,  sol- 

Precipitate, in- 

but   dissolves 

uble   in   solu- 

soluble in  sol- 

in    acid.       Is 

tions  of  alka- 

iitions  of    al- 

precipitated 

line  salts. 

kaline  salts. 

when    heated 

with  alkaline 

salts. 

Mineral  acids. 

]S^o  precipitate. 

Precipitate,  sol- 

Precipitate,sol- 

uble in  excess. 

uble  in  excess. 

Tannic  acid. 

Yellow  precip- 
itate. 

Opalescence. 

No  effect. 

Acetate  of  lead. 

No  precipitate. 

Precipitate, 

Precipitate  by 

partly  soluble 

basic    acetate 

m  excess. 

of  lead. 

Alum. 

No  precipitate. 

Precipitate,  sol- 
uble in  excess. 

Precipitate. 

Mercuric  chlo- 

White   precip- 

Opalescence 

Slight    turbid- 

ride. 

itate. 

only. 

ity. 

When    decom- 

Leucinandgly- 

Leucin ;  no  glj'- 

Leucin  and  ty- 

posed  by  boil- 

cocin      form- 

cocin ;       also 

rosinandbody 

ing   in   dilute 

ed  ;  no  sugar 

chondroglu- 

s  imilar   to 

acids. 

stulT. 

eose. 

chondroglu- 
cose. 

Chap.  V.— NITROGENOUS  PROXIMATE  PRINCIPLES  OTHER  THAN 
THE  PROTEIDS. 

A.  Fatty  Niteogenous  Matters. 

There  are  at  least  four  bodies  that  may  be  classed  imder  this  head — 
lecithin,  cholin  or  neurin,  phospho-glyceric  acid,  and  cerebrin — all  of 

^  Compiled  from  Gamgee's  Physiological  Chemistry,  vol.  i. 

^  See  Charles'  Physiological  and  Pathological  Chemistry,  p.  134. 


82  THE  CHEMISTRY  OF  THE  BODY. 

which  are  related  chemically  and  physiologically  to  a  substance  called 
protagon,  already  referred  to. 

1.  Protagon,  CjeoHgogNgPOyj,  is  a  substance  existing  in  nervous  matter, 
and  specially  in  the  brain  and  spinal  cord  ;  it  is  also  found  in  the  coloured 
and  colourless  blood  corjjuscles,  in  most  animal  fluids,  and  in  yolk  of  egg. 
It  is  a  neutral  substance,  insoluble  in  water,  soluble  in  boiling  alcohol  and 
in  boiling  fats,  but  is  insoluble  in  cold  alcohol.  AVhen  boiled  with  baryta 
water  it  yields  glucose,  phospho-glyceric  acid  (CgH^PO,.,),  and  a  body 
similar  to  neurin,  but  differing  from  it  by  having  one  molecule  of 
water  less  than  neurin — thus,  CjH^gNO.  According  to  Hojipe-Seyler, 
protagon  is  a  mixture  of  lecithin  and  cerebrin,  whilst  Bayer  regards 
it  as  a  glucoside.  It  has,  however,  been  conclusively  established  by 
Gamgee  and  Blankenhorn  that  it  is  a  definite  chemical  body,  thus 
confirming  the  original  opinion  of  its  discoverer,  Liebreich. 

2.  Lecithin,  C^Hg^XPOg  +  H^O,  is  also  found  in  nervous  matter,  in 
the  blood  corpuscles,  and  in  j^olk  of  egg.  AVhen  obtained  from  eggs, 
it  is  a  white,  waxy,  hygroscopic  mass,  coloiu^less,  soluble  in  alcohol, 
ether,  chloroform,  sulphide  of  carbon,  benzol,  and  in  the  fats.  When 
heated  Avith  baryta  water,  it  is  split  up  into  phospho-glyceric  acid, 
cholin,  neurin,  and  stearate  of  baryta.  "\'\Tien  ignited  it  burns  away, 
lea\ing  as  a  residue  only  metaphosphoric  acid.  (Gamgee.)  Dr.  Gamgee 
doubts  its  existence  in  quantity  in  the  brain  tissue,  and  he  says  that 
among  the  numerous  phosphorized  matters  obtained  from  an  alcoholic 
solution  of  brain  matter,  lecithin  is  to  be  reckoned.  No  sufficient 
proof  of  its  identity  has,  however,  yet  been  furnished.  Such  matters 
from  an  alcoholic  extract  of  brain  are  protagon,  cholesterin,  and  a 
group  of  phosphorized  bodies,  to  which  the  general  name  cerehin  may 
be  applied.  To  understand  the  constitution  of  lecithin,  consider,  in  the 
first  place,  its  relations  to  phospho-glyceric  acid  and  neiu'in. 

a.  Phospho-glyceric  acid,  CgHgPOg,  or  C3H5 .  (OH), .  0  .  PO  .  (OH),, 
may  be  obtained  pure  as  a  syrupy  licj[uid,  easily  decomposed  by  heat 
into  glycerine  and  phosphoric  acid,  of  which  substances  it  is  really  a 
combination.     Thus — 

r  OH  r  OH  (OH 

C3H5J  OH  -(-  HaPOi     =     C3H54  OH         or  C3H5  ^  OH  +H0O. 

tOH  IPO4H0  (O.PO(OH)o 

Glycerine.  Phospho-glyceric  acid. 

One  molecule  of  water  is  formed,  and  it  may  be  said  that  phospho- 
glyceric  acid  is  produced  by  the  union  of  glycerine  and  phosphoric  acid 
with  the  loss  of  one  molecule  of  water. 

h.  Neurin  or  Cholin,  C^H^^XOg,  is  also  formed  by  the  decomposition 
of  lecithin,  and  it  is  identical  with  one  of  the  constituents  of  the  bile 


FA  TTY  NITROGENO US  MA  TTERS.  83 

acids.  It  is  a  syrupy  liquid,  soluble  in  alcohol  and  ether,  and  alkaline 
in  reaction.  It  may  be  thus  represented  :  CgH^ .  Isr(CH3)3 .  (011)2. 
When  heated  it  decomposes  into  ethylene  glycol  and  trimethylamine, 
and  it  will  be  observed  that  the  hydroxyls  are  united  to  the  ethylene 
glycol.     Thus — 

C2H4.N(CH3)3.(0H),     =     C2H,.(0H).     +     ^{CY^^)^. 

Neuiin.  Ethylene  glycol.        Trimethylamine. 

Neurin  has  been  formed  synthetically.     (Gamgee.) 

Now,  lecithin  may  be  regarded  as  built  on  the  type  of  phospho- 
glyceric  acid,  in  which  two  of  the  hydrogens  are  replaced  by  the 
radicle  of  a  fatty  acid  (oleic,  stearic,  pabnitic),  while  one  atom  of 
hydrogen  of  the  phosphoric  acid  is  replaced  by  one  molecule  of  cholin, 
less  one  molecule  of  hydroxyl.     Thus — 

fOH 

CgHg-^    OH  ; 

tO.PO(OH)2 

Phospho-glyceric  acid. 

then  CjgHgy  -  H^O  +  0  =--  CjgHgjO,  radicle  of  stearic  acid ;  then 

I   0  .   CigHggO 

[^•^^\     0  .  C2H4 .  N(CH3)3 .  OH  ; 
Lecithin. 

or,  C44H9QNPO9,  supposing  the  radicle  of  stearic  acid  exists  in  the 
compound,  which  may  be  called  distearyl-lecithin. 

Thus,  by  its  decomposition,  lecithin  may  yield  phospho-glyceric  acid, 
glycerine,  trimethylamine,  and  ethylene  glycol,  and  this  may  account 
for  the  occasional  appearance  of  trimethylamine  in  some  of  the  secre- 
tions. A  consideration  of  its  constitution  also  suggests  its  relationship 
to  cholin — one  of  the  products  of  the  decomposition  of  the  bile  acids. 

3.  Cerebrin  is  a  substance  of  varying  formulae  extracted  from  nervous 
matter,  and  differing  from  lecithin  in  not  containing  phosphorus. 
There  is  no  trustworthy  evidence  that  it  is  a  definite  chemical  com- 
pound. Gamgee  has  extracted  from  the  brain  by  alcohol  at  45°  C.  a 
body  which  he  has  provisionally  named  pseudo-''.erelrin,  and  to  which  he 
attaches  the  formula  C^^Hg^iSrOg.  Dr.  Thudichum  states,  as  the  result 
of  an  elaborate  research,  that  he  has  separated  from  brain  matter 
phosphorized  bodies  belonging  to  three  groups — the  keplialins 
(C42H79NPO13),  the  myelins,  of  varying  formulae  (C^oHgoNPOg, 
C,oH,,NPO,o>  C^oHg^N^PO^o,  C.^H.^gK^POg,  Cg^Hg^NPOg,^  and 
C39Hg2lSr,POg),  and  the  lecithins — bodies  of  great  instability,  and 
hence  of  uncertain  composition.  ^ 

^  For  a  full  critical  account  of  this  difficult  subject,  see  Gamgee's  Physiological 
Chemistry,  vol.  i.  pp.  425-447  ;  also  Dr.  Thudichum's  Research,  Reports  of  Medical 
Officer  of  the  Privy  Council  and  Local  Government  Board,  1874,  p.  113  et  seq. 


84 


THE  CHEMISTRY  OF  THE  BODY. 


B.  The  Amides. 
1.   Urea. — The  typical  substance  belonging  to  this  group  is  urea, 
CH4N0O.     It  may  be  regarded  as  constructed  on  the  ty})e  of  two  mole- 
cules of  ammonia,  in  which  two  hydrogens  are  replaced  by  the  dyad 
radical  CO,  thus- 


N 


N 


NH., 


-CO  =  CO 


NH., 


CON.H^. 


It  is  thus  a  carbamide.  This  view  shows  how,  by  uniting  ^^dth  Avater, 
urea  is  readily  changed  into  carbonate  of  ammonia — 

C0|NH:+g:0  =  C0|g;^g^0r(NH,),C0, 

Urea.  Carbonate  of  ammonia. 

Again,  urea  is  related  to  cyanic  acid,  which  may  be  looked  on  as  a 
carbamide,  that  is,  ammonia  in  which  two  atoms  of  hydrogen  are 
replaced  by  CO— 


N 


N 


CO 
H  ' 


or  HCNO. 


Cyanic  acid. 

Cyanic  acid  Avith  water  changes  into  carbonic  acid  and  ammonia,  and 
cyanate  of  ammonia  is  readihT-  transformed  into  urea  merely  by  mole- 
cular rearrangement — 

HCNO   -f-   HoO  =  CO.  +  NH.„  and 

NH4CNO'      -        CN0H4O. 
Cyanate  of  ammonia.  Urea. 

Urea,  found  chiefly  in  the  urine,  is  also  met  -with  in  the  blood,  lymph, 

chyle,  bile,  aqueous  and  vitreous 
humours  of  the  eye,  and  in  many 
of  the  liquids  of  the  body.  It  is 
also  found  in  nearly  all  the  organs, 
and  especially  in  the  liver,  spleen, 
and  lungs.  About  .30  grammes 
on  an  average,  Avith  a  mixed  diet, 
are  excreted  by  the  kidneys  of 
an  adult  man  in  24  hours.  It  is 
always  increased  in  amount  by  a 
diet  rich  in  proteids ;  but  it  does  not 
disappear  from  the  urine  even  during 
starvation,  as  the  individual,  in  a 
sense,  then  lives  on  the  tissues  of 
the  body,  and  practically  the  diet, 
if   one  can  apply  the   term   to   food  thus   supplied,  contains   protcid 


Fig.  2."). — Urea.  a.  Four-sided  prisms  ; 
I).  Indefinite  crystals,  such  as  are 
usually  formed  in  alcoholic  solutions. 


THE  AMIDES, 


85 


matter.  When  obtained  pure,  it  consists  of  elongated,  prismatic, 
four-sided  crystals,  terminated  by  one  or  two  oblique  surfaces.  (See 
Fig.  25.)  Nitric  acid  forms  nitrate  of  urea,  a  salt  which  takes  the  form 
of  octahedra,  or  lozenge-shaped  tablets,  or  hexagons  (Fig.  26).  Oxalic 
acid  forms  flat  or  prismatic  crystals  of  oxalate  of  urea  (Fig.  26).     Urea  is 


O.o 


Fig.  26. — Nitrate  and  Oxalate  of  Urea,    a,  a.  Nitrate  of  urea  ;  &,  b.  Oxalate  of  urea. 

inodorous,  and  has  a  bitterish-saline  taste.  It  is  soluble  in  water  and 
alcohol,  but  not  in  ether.  It  is  not  precipitated  by  acetate,  nor  by 
subacetate  of  lead,  but  it  is  thrown  down  by  mercuric  nitrate,  forming 
a  whitish  precipitate,  having  the  formula  (CO]Sr2H4)2Hg(N03)2  +  3HgO, 
and  containing  urea  and  mercuric  oxide  in  the  proportion  of  10  to  72. 
Mtrous  acid,  chlorine,  hypochlorite  and  hypobromite  of  soda  decompose 
it  into  nitrogen  and  carbonic  acid — 


CONOH4  +  N203 

=  CO2  +   2HoO  +  2N2. 

CONgH^  +  H0O  +  3CI2 

=  COo  +  No  -t-  6HC1. 

CON0H4  +  SNaBrO 

=  COo  -K   No  +  2H20-(-3NaBr. 

On  the  reaction  of  mercuric  nitrate  with  urea  depends  Liebig's  well-known 
volumetric  process  for  the  estimation  of  the  amount  of  urea  in  a  fluid,  and  on  its 
reaction  with  hypobromite  of  soda  is  founded  the  method  of  determining  the 
amoiint  of  urea  from  the  amount  of  nitrogen  evolved,  devised  first  by  Knop  and 
since  modified  and  improved  by  many  chemists.  These  methods  will  be  described 
in  treating  of  the  analysis  of  the  urine. 

By  fermentation,  under  the  action  of  a  specific  organism  {Micrococcus 
Urece),  it  is  transformed  into  carbonate  of  ammonia — 
CON2H4  -t-  2H2O    =  (NH4)2C03. 

Urea.  Carbonate  of  ammonia. 

When  dry  chlorine  is  passed  over  urea,  the  following  reaction  occurs — 

3(CON2H4)   4-  SCla  =  C3H3O3N3  +  N2  +  5HC1  +  NH4CI. 
Urea.  Cyanuric  acid. 


86  THE  CHEMISTRY  OF  THE  BODY. 

When  heated  with  a  mixture  of  caustic  potash  and  })ermanganate  of 
potash,  it  is  decomposed  into  carbonic  acid  and  ammonia.  There  is 
still  considerable  obscurity  as  to  the  origin  of  urea,  but  the  evidence 
will  be  better  appreciated  after  a  study  of  the  metabolic  changes  occur- 
ring in  the  tissues,  and  more  especially  after  the  study  of  the  functions 
of  the  liver  and  kidneys.  It  is  sufficient  to  state  here  that  there  is  no 
evidence  showing  that  it  is  derived  from  uric  acid.  No  doubt  it  is  a 
product  of  the  splitting  up  of  nitrogenous  matters.  We  have  seen  that 
decomposition  of  the  albumin-molecule  may  produce  leucin,  ty rosin, 
glycocolle,  and  amido-acids  or  amides ;  and  these  substances,  especiall}' 
the  two  first,  are  found  in  the  alimentary  canal,  and  probably  are  thence 
absorbed  and  carried  to  the  liver.  In  cases  of  acute  atrophy  of  the 
liver,  urea  is  said  to  disappear  from  the  urine,  and  it  has  been  supposed 
that  this  occurs  because  the  hepatic  cells  cannot  effect  such  chemical 
changes  on  leucin  and  tyi'osin  as  normally  produce  urea.  Further,  the 
direct  injection  of  leucin  and  glycocolle  into  the  bowel  increases  the 
amount  of  urea,  and  "  all  the  nitrogen  of  the  leucin  and  of  the  glyco- 
colle appears  in  the  urea."  (Beaunis.)  It  will  be  seen  that  this  is  strong 
presumptive  e'vddence  in  favour  of  the  Aaew  that  urea  may  be  a 
decomposition  product  of  such  bodies ;  but  one  must  admit  that  the 
effect  maj'  be  due  not  to  a  direct  transformation,  but  to  the  action  of 
leucin  and  its  allies  on  the  general  metabolism  of  proteid  matter  in 
the  liver.  It  has  also  been  sho^^ai  that  amides,  such  as  glycocolle, 
sarcosin,  and  taurin,  when  introduced  into  the  body  so  as  to  be  carried 
to  the  liver,  increase  the  urea  (Salkowski),  but  they  may  appear  in  the 
urine  as  uramides,  that  is,  bodies  formed  by  a  combination  of  NHCO 
(cyanic  acid)  "vnth  the  amide  introduced.  Thus  glycocin  and  cyanic 
acid  form  hydantoinic  acid,  sarcosin  (methyl-glycocolle)  with  cyanic  acid 
forms  methyl-hydantoinic  acid  (Schultzen),  and  taurin  with  cyanic  acid 
forms  tauro-carbamic  acid  (uramo-isthionic  acid)  (Salkowski) — 

NH2 .  CH, .  CO  .  OH  +  CO  .  NH  =  NH  .  CONH, .  CH, .  CO  .  OH. 

Glycocolle.  Cyanic  acid.  Hydantoinic  acid. 

NHo .  CH„ .  CHo .  SO, .  OH  -f  CO .  NH  =  NH .  CONH, .  CH, .  CH, .  SO, .  OH. 

Taurin.  Cyanic  acid.  Tauro-carbamic  acid. 

There  is  e\ddently  then  some  relation  between  glycocolle,  sarcosin, 
leucin,  tyrosin,  and  urea,  although  the  chemist  has  not  succeeded  in 
effecting  a  direct  transformation  of  any  of  these  bodies  into  urea.  But 
if  not  directly  derived,  may  not  urea  originate  from  certain  bodies  in 
their  turn  springing  from  the  amides,  glycocolle,  sarcosin,  etc.,  or  at  all 
events  having  a  common  origin  "sWth  these  1  For  example,  suppose  by 
decomposition  of  albuminoids  that  cyanic  acid  were  produced,  then  one 
can  conceive  urea  originating  thus — 


THE  AMIDES.  87 

NHCO    +    NHCO  +  HjO  =  CON^H^  +  CO.,. 

Cyanic  acid.  Cyanic  acid.  Urea.  Carbonic  acid. 

Chemists  have  not  yet  found  cyanic  acid  as  a  product  of  the  decom- 
position of  the  amides,  so  that  this  origin  of  urea  is  doubtful.  Another 
theory  that  has  been  put  to  the  test  of  experiment  with  unsatisfac- 
tory results  is,  that  urea  may  be  produced  by  the  formation  from 
albuminoids  of  ammonia,  and  that  the  carbonate  of  ammonia  produced 
by  the  union  of  ammonia  with  carbonic  acid  may  then,  by  losing  water, 
become  urea.  To  test  this  view,  salts  of  ammonia  have  been  administered 
to  animals,  and  the  effect,  if  any,  on  the  elimination  of  urea  has  been 
scrutinized.  Kniriem  and  Salkowski  state  that  the  urea  eliminated  by 
the  rabbit  is  increased  by  giving  the  animal  chloride  of  ammonium 
or  nitrate  of  ammonia;  in  the  dog,  however,  Salkowski  did  not  ob- 
serve this  effect.     The  point  in  dispute  is  thus  stated  by  Beaunis — 

"  This  fact,  which  led  Voit  and  Feder  to  deny  the  results  obtained  by  Kniriem 
and  Salkowski,  has  been  explained  by  Schmiedeberg  and  his  pupils,  by  showing 
how  differently  the  dog  and  the  rabbit  are  influenced  by  acids.  Schmiedeberg  and 
Walter  have  shown  that  in  the  dog,  the  ingestion  of  hydrochloric  acid  increases 
notably  the  elimination  of  ammonia  by  the  urine  ;  this  ammonia,  necessary  for 
the  elimination  of  hydrochloric  acid,  the  latter  takes  from  the  organism  ;  but  if, 
instead  of  the  hydrochloric  acid  being  introduced  in  a  free  condition,  it  is  introduced 
in  chloride  of  ammonium,  there  is  no  formation  of  urea,  because  the  ammonia  is  re- 
tained by  the  hydrochloric  acid,  which,  in  place  of  borrowing  the  ammonia  from 
the  organism  itself,  employs  that  directly  supplied.  This  is  shown  by  the  fact 
that  if  a  dog  receives  carbonate  of  ammonia  instead  of  the  chloride  of  ammonium, 
a  part  of  the  carbonate  appears  in  the  urine  as  urea.  If,  however,  following  the 
example  of  Munk,  the  organism  of  the  dog  is  placed  in  the  same  conditions  as  that 
of  a  rabbit  by  rendering  the  urine  alkaline  by  a  vegetable  diet,  then  the  chloride 
of  ammonium  only  appears  partially  in  the  urine,  a  half,  or  less,  of  the  salt  intro- 
duced contributing  to  the  formation  of  urea."  ^ 

If  then  ammoniacal  salts  increase  the  amount  of  urea  eliminated,  we  may 
suppose  with  Salkowski  that  cyanic  acid  arising  from  the  decomposition 
of  proteids  unites  with  the  ammonia  to  form  cyanate  of  ammonia,  which, 
by  molecular  transformation,  then  becomes  urea.  Normally  then  the 
reaction  would  be  thus — 

CO.NH  4-  CO.NH  +  H^O  =  CON2H4  +  CO2. 

Cyanic  acid.       Cyanic  acid.  Urea. 

whilst  the  reaction  after  the  administration  of  ammonia  woidd  be — 
2C0NH     +     2NH3     =     2CO]Sr2H4. 

Cyanic  acid.  Ammonia.  Urea. 

Thus,  whilst  it  is  clear  that  urea  results  from  decomposition  of  proteid 

matters,  the  exact  steps  by  which  this  is  accomplished  are  unknowai, 

^  Beaunis,  op.  cit.  vol.  i.  p.  147. 


88 


THE  CHEMISTRY  OF  THE  BODY. 


and  the  question  whether  nrea  may  arise  from  decomposition  onl_y,  or  from 
the  synthesis  of  products  of  decomposition,  is  still  unsettled. 

2.  Oxalurk  acid,  C-jH^NoO^. — This  substance  is  urea  in  which  one 
atom  of  hydrogen  is  replaced  l^y  the  residue  of  oxalic  acid,  that  is  oxalic 
acid  CgHqOj,  minus  hydroxy],  HO  or  C^O.jH — 


CO 


NH., 


NHo 

Urea. 


CO 


NH., 

NH'.  C,0;)H. 

Oxaliiric  acid. 


Heated  in  the  presence  of  water,  it  is  decomposed  into  oxalic  acid  and 
oxalate  of  urea — 


2(C3H4N204)     +     2(H,0)     = 

Oxaluric  acid.  Water. 


(CH4N,0).C,H,04 

Oxalate  of  urea. 


+     C,H,0,. 

Oxalic  acid. 


The  nature  of  this  acid  Avill  be  further  referred  to  in  discussing  uric 
acid  and  its  derivatives,  of  which  oxaluric  acid  is  one. 

3.  Allantow,  C^H^N^Og,  is  also  a  derivative  of  uric  acid,  found  in  the 
amniotic  and  allantoic  fluids  of  the  emliryo,  in  the  urine  of  neAvly-borii 
children,  and  in  the  urine  of  certain  animals,  such  as  the  clog  and  cat. 
It  may  be  formed  artificially  by  treating  uric  acid  with  water  and  per- 
oxide of  lead,  or  by  acting  on  uric  acid  Avith  potassium  ferrocyanide  and 
caustic  potash.  It  forms  shining  colourless  prisms  (Fig.  27),  is  taste- 
less, and  is  soluble  in  160  parts  of 
water  at  20°  C.  and  in  30  parts  of 
boiling  water.  Heated  with 
nitric  or  hydrochloric  acids,  it  is 
changed  into  uric  and  allanturic 
acids ;  sulphiuric  acid  splits  it  up 
into  carbonic  acid,  carbonic  oxide, 
and  ammonia,  Avhilst,  when  boiled 
with  baryta  water,  it  gives  oft* 
ammonia  and  i:)recipitates  oxalate 
of  bariimi.  When  1  part  of  gly- 
oxalic  acid  is  heated  with  2  parts  of  urea  to  100°  C.  for  eight  or  ten 
hours,  allantoin  is  formed,  and  from  this  reaction  it  is  regarded  as  the 
diureide  of  glyoxalic  acid,  thus — 

NH  -  CH  -  NH  -  CO  -  NH., 
CO  I 

NH  -  CO 

Pelouze   discovered   an   acid,    allanturic   acid,  C-.HjoNp,Og(?),    produced 
from  allantoin  by  the  action  of  dilute  nitric  acid,  thus — 

H„0     = 


Fio.  27. — Allantoin. 


2(C,H6N,03) 

Allantoin. 


C^HjoNfiOe 
Allanturic  acid. 


CONgH^. 

Urea. 


THE  A  MIDO-A  GIBS. 


89 


Chap.  VL— NITROGENOUS  PROXIMATE  PEINCIPLES. —Continued. 

The  Amides,  or  Amido-Acids. 

When  we  examine  the  chemical  constitution  of  plants,  we  find  they 
contain  non-nitrogenous  and  nitrogenous  bodies.  As  examples  of  the 
former,  we  have  (1)  carbohydrates,  such  as  cellulose,  starch,  dextrin,  gum, 
and  cane  and  grape  sugar ;  (2)  the  varieties  of  the  essential  oils  and 
resins ;  and  (3)  vegetable  acids.  The  nitrogenous  compounds  comprise 
in  addition  to  proteids,  the  colouring  matters  of  plants,  the  j)rincipal  of 
which  is  chlorophyll,  and  organic  bases  termed  alkaloids.  These  bases 
contain  nitrogen,  in  addition  to  carbon,  oxygen,  and  hydrogen.  The 
following  are  examples — 


Aconitine, 
Asparagiae, 
Atropine, 
Biberine,  - 
Br  u  cine,  - 
Caflfein,     - 
Cinchonine, 
Codeine,  - 
Conine,     - 
Morphine, 
Narceine, 
Narcotine, 
Nicotine,  - 
Papaverine, 
Quinine,   - 
Kinoline, 
Sinapine,  - 
Strychnine, 
Thebaine, 
Theine,     - 
Theobromine, 


C30H47NO7 
C4H8N2O3  - 
CiyH^NOa 
C19H21NO3 

C2sF,6N204 

CsH.oN^O, 
C,oH24N,0 
C18H21N2O3 

C3H15N  - 
C17H19NG3 

C^H^gNOg 

C^^HasNOy 

^loHi4N2     - 

C.,oH2iN04 

C,oH24N,0, 

C9H7N  - 
C16H23NO5 

C^iH^^N^Oa 
Ci9H,iN,03 
C8H10N4O2 
C7H8N4O2  - 


Aconitum  napellus. 

Asparagus  officinalis. 

Atropa  belladonna. 

Biberis  vulgaris. 

Strychnos  nux  vomica. 

Tea,  coffee,  etc. 

Cinchona  bark. 

Opium. 

Conium  maculatum. 

Opium. 

Opium. 

Opium. 

Tobacco. 

Opium. 

Cinchona  bark. 

Cinchona  bark. 

White  mustard. 

Strychnos  nux  vomica. 

Opium. 

Tea,  coffee. 

Cacao  beans. 


Chemically,  these  bodies  are  regarded  as  compound  ammonias — that 
is,  bodies  in  which  one,  two,  or  three  equivalents  of  hydrogen  are  re- 
placed by  radicles.  Thus  conine  may  be  rejoresented  as  ammonia  in 
which  two  atoms  of  hydrogen  are  replaced  by  the  monatomic  radicle, 
C4H7,  and  nicotine  as  a  condensed  ammonia  in  which  all  the  atoms  of 
hydrogen  are  replaced  by  the  triatomic  radicle  CgHy.     Example— 


(C4H,)^ 
H 


MN  =  aH,,N. 


Conine. 


C5H7 

CgHy 

Nicotine. 


No  =  C,„a4N, 


In  the  animal  economy  certain  bodies  are  found  which  apparently 


CgH^NO, 

Cystin,     - 

-      C,H-NSO., 

C,,H„N03 

Sarcin,     - 

-      CgH.N.O^ 

CHgNO., 

Xanthiu,- 

-      CsH^NA 

c;h7no;s 

Guaiiin,    - 

-      C5H5N5O 

C:HgN30, 

Alloxan,  - 

-      C,H,N,0, 

C4H7N3O 

Urea, 

-      CH4N,,0 

90  THE  CHEMISTRY  OF  THE  BODY. 

have  a  somewhat  similar  chemical  structure.  They  differ  in  chemical 
composition  from  the  vegetable  alkaloids,  however,  by  containing  less 
nitrogen  and  oxygen  in  proportion  to  the  amount  of  carbon.  These 
substances  are — 

Leucin,      .        -        - 

Tyrosin,     - 

Glycocin  or  glycocoUe, 

Taurin, 

Creatin, 

Creatinin,  - 

It  is  probable  that  certain  of  these  bodies  are  amides — ammonias  in 
which  one  or  more  atoms  of  hydrogen  are  replaced  by  radicles  of  an 
acid,  or  amido-acids — that  is,  acids  in  which  one  or  more  hydrogen  atoms 
of  the  radicle  of  the  acid  are  replaced  by  NH^.  Thus  lU'ea,  as  already 
explained,  may  be  regarded  as  carbamide,  or  ammonia  containing  the 
diatomic  radicle  of  carbonic  acid.     Example — 

g^N,  CO  Ho  (  N.,  =  CH^K.O. 

^^■f  '  h:  i  "        ■ 

Ammonia.  Badicle  of  CO2.  Carbamide.  Urea. 

In  like  manner,  on  the  type  of  one  molecule  of  water,  glycocin  may 
be  regarded  as  amido-acetic  acid,  leucin  as  amido-caproic  acid,  and  sar- 
cosin,  one  of  the  derivatives  of  creatin,  as  amido-methyl-acetic  acid. 
In  the  amido-acid  group  of  the  latter  substance  one  atom  of  hydrogen  is 
replaced  by  CHg  (methyl),  thus — 


CsHioONHolo 
H  J  ^ 

C.,H0(CH3)NH.,  )  , 

hT 

or 
C2H5NO, 
Glycocin  or  amido- 
acetic  acid. 

or 
CeHigNO, 

Leucin  or  amido- 
caproic  acid. 

or 
C3H-NO0 

Sarcosin  or  methyl- 
glycocin,  or  amido- 
methyl-acetic  acid. 

The  amides  are  often  conjugated  bodies,  and  they  may  behave  either 
as  bases  forming  unstable  compounds  with  acids,  or  they  may  play  the 
part  of  feeble  acids,  which,  A\"ith  the  loss  of  water,  unite  with  alkaline 
bases.  The  chief  point  of  physiological  importance  is  their  instability^ 
especially  under  the  conditions  prevailing  in  the  living  body. 

1.  GlycocoUe,  or  Glycm,  or  Glycocin,  CoHjXOg,  as  above  sho^vn,  is 
amido-acetic  acid.  It  forms  a  constituent  of  glycocholic  acid,  one  of 
the  acids  of  the  bile.  Combining  Avith  benzoic  acid,  it  forms  hippuric 
acid.  "When  uric  acid  is  acted  on  with  warm  hydriodic  acid,  it  splits 
up  into  glycocoUe,  iodide  of  ammonium,  and  carbonic  acid,  a  reaction 
which  indicates  that  glycocoUe  is  related  to  uric  acid — 

CgH4lir403     +     SHI     +     5H2O     =     CoHgNO.     -f     3NH4I     +     SCOj. 

Uric  acid.        Hydriodic  acid.  GlycocoUe.  Iodide  of  Carbonic  acid. 


ammonium. 


THE  AMIDO-ACIDS. 


91 


The  decomposition  of  gelatin  yields  glycocolle  among  other  substances, 
and  it  is  possible  that  glycocolle  may  be  produced  in  the  liver  from 
gelatin  absorbed  from  the  alimentary  canal.  Glycocolle,  when  thus 
formed,  unites  Avith  cholalic  acid  to  produce  glycocholic  acid,  and  it  may 
also  unite  with  any  benzoic  acid  present  to  form  hippuric  acid.  In  the 
intestine,  no  doubt,  glycocholic  acid  is  decomposed,  and  the  glycocolle 
liberated  passes  into  the  blood.  It  has  been  suggested  that  it  may 
then  be  decomposed  into  methylamine  and  carbonic  acid,  thus — 


CH.  .  NH., 
1 
CO  .  OH  . 

=      N 

H 

H      + 
CH3 

CO 

Glycocolle. 

Methylamine. 

This   methylamine    (not   found   free   in   the   body),   may,   in   certain 

circumstances,    form    trimethylamine,   which    sometimes    is    present. 

Again,    the   oxidation   of   glycocolle   produces    carbonic    acid,    oxamic 

acid,    oxalic    acid,    and   water;    and    oxamic 

acid,    ill    turn,    is    readily    decomposed    into 

ammonia  and  oxalic  acid.      In  a   pure  state, 

glycocolle  appears  in  the  form  of  rhombohedric 

or    prismatic    crystals    (Fig.    28),     having    a 

sweetish    taste.      These    are   soluble   in   cold 

water,  and  they  are  insoluble  in  cold  alcohol 

and  ether.      The   solution  is    acid.      When  a 

solution  of  glycocolle  is  boiled  with  a  solution 

of  hydrated  cupric  oxide,  a  blue  solution  is 

formed,  from  which  bluish  needle-shaped  crystals 

separate  on  cooling. 

2.  Leucin,  C^-^^O.j,  is  amido-caproic  acid, 
leucic  acid,  or  oxy-caproic  acid,  that  is  to  say,  the  hydroxyl  of  leucic 
acid  is  replaced  in  leucin  by  the  radicle  NH,.     Thus — 

CH3  CH2 .  OH  CH2 .  NH2 


Fig.  2S.— Glycocin,  or  glyco- 
colie,  or  glycin. 

It  is  related  to  an  acid. 


(CHs)^ 
CO.  OH 

Caproic  acid. 


(CHa)^ 
CO.  HO 

Leucic  acid  or  oxy- 
caproic  acid. 


(CHa)^ 

I 
CO.  HO 

Leucin. 


It  has  already  been  pointed  out  (p.  59)  that  leucin  exists  in  consider- 
able amount  among  the  decomposition  products  of  proteids  when  the 
proteids  are  split  up  by  the  action  of  strong  caustic  alkalies  or  sulphuric 
acid.  Leucin  is  also  formed  when  proteids  are  decomposed  by  putre- 
faction and  by  pancreatic  digestion.  It  is  found  in  many  of  the  tissues 
and  organs,  more  especially  in  the  pa  creas,  and  in  smaller  quantities 


92 


THE  CHEMISTRY  OF  THE  BODY. 


ill  the  liver,  kidneys,  spleen,  thymus,  lymphatic  glands,  and  the  brain. 

In  some  pathological  conditions,  such  as  leidcremia  and  acute  atrojjhy  of 

the  liver,  it  is  found  in  the 
urine  in  the  form  of  yellowish- 
hrown  lialls  (Fig.  29)  or 
spheres,  highly  refractive,  and 
consisting  of  masses  of  fine 
needle-shaped  crystals.  Leu- 
cin  is  inodorous,  it  is  soluble 
in  water,  slightly  in  alcohol, 
l)ut  not  in  ether.  Its  solu- 
tions are  neutral  in  reaction 
and  almost  tasteless.  Leucin 
originates  in  the  body  by  the 
decomposition  of  proteids. 
In  turn,  it  splits  up  into  fatty 
acids  and  ammonia.  Thus, 
by  heat  it  is  decomposed  into 
carbonic  acid  and  amyl- 
amine — 


■^^^ 


Fig.  29. — Spheroidal  crystalline  masses  of  leucin. 
a,  A  very  minute  simple  spherule  ;  b,  hemispher- 
oidal  masses  ;  c,  c,  a;,^gi-egates  of  small  globules  ; 
d,  a  larger  globule  supporting  two  halves  ;  e,  /, 
large  spheroids  richly  studded  with  minute  seg- 
ments ;  (I,  g,  (I,  ri,  laminated  globules,  some  with 
smooth,  some  with  rough  surface,  and  of  very 
various  sizes. 


CH.,.NH., 

1 

CH., .  NH., 

1 

:GB.^)i 

(CH2)3 

CO .  OH . 

CH3 

Leucin. 

Amylamine. 

+      CO., 


By  hydriodic  acid  it  is  decomposed  into  caproic  acid  and  ammonia, 
thus — 

CH.,.NHo  CH, 


(CH.)4 

CO . OH . 

Leucin. 


+      2H      =     (CH2)4 


+     NH,. 


CO . OH . 

Caproic  acid. 


With  concentrated  sulphuric  acid,  leucin  yields  ammonia  and  valeric 
acid,  and  with  permanganate  of  potash,  oxalic  acid,  carbonic  acid, 
valeric  acid,  and  ammonia.  Possibly,  in  the  body,  similar  decomjoosi- 
tions  may  occur,  which  accounts  for  the  traces  of  these  substances 
found  in  some  organs.  Thus,  valeric  acid  has  been  found  in  the  sweat 
and  in  epidermic  matters  containing  leucin.  It  has  also  been  conjec- 
tured that  leucin  may  be  one  of  the  steps  towards  the  formation  of 
urea,  and  this  is  supported  experimentallj-  by  the  fact  that  the  admini- 
stration of  leucin  to  dogs  increases  the  amount  of  urea  eliminated  by 
the  Iddneys. 


THE  AMIDO-AGIDS. 


98 


3.  Tyrosin,  CgHj^^NOg,  is  the  amide  of  oxyplienylpropionic  acid,  and 
is  related  on  the  one  hand  to  a  fatty  acid,  propionic  acid,  and  on  the 
other,  to  phenic  acid,  an  aromatic  substance,  thus — 

CH,  CH3  CH3  CH3 

I  I  I  I 

CH.  CH .  NH.       CH .  (CfiHj  .OH)      C  .  (CgHi .  OH)NH, 

I    ■  I  '      I  ■  ! 

CO  .OH         CO .  OH         CO  .OH  CO .  OH  . 

Propionic  acid.        Alaain.        Oxyphenylpropionic  acid.  Tyrosin. 

Here  observe  that  one  atom  of  hydrogen  in  propionic  acid  is  replaced  by 
the  radicle  oxyphenyl  (C^H^  .  OH),  and  when  the  remaining  hydrogen 
in  oxyphenylpropionic  acid  is  replaced  by  NH.,,  tyrosin  is  produced  ; 
or,  as  shown  above,  tyrosin  may  be  looked  on  as  alanin  (the  amide  of 
propionic  acid),  in  which  one  atom  of  hydrogen  is  replaced  by  oxy- 
phenyl. Tyrosin  is  usually  found  along  "vvith  leucin,  and  like  it, 
results  from  the  decomposition  of  proteids.  Occasionally  found  in  the 
urine,  it  is  probably  entirely  decomposed  in  the  body,  and  it  has  been 
sho^vn  that  the  administration  of  tyrosin  to  a  living  animal  is  not 
followed  by  its  apjjearance  in  the  urine,  but  by  the  appearance  of 
.phenol  and  phenol-sulphates,  indicating  its  relation  to  the  aromatic 
compounds.  Tyrosin  crystal- 
lizes in  slender,  colourless,  mi- 
croscopic needles  (Fig.  30).  It 
is  slightly  soluble  in  cold  water, 
but  is  insoluble  in  alcohol  and 
ether.  Whilst  burning,  it  smells 
like  burnt  horn.  Oxidation  by 
bichromate  of  potash  yields  oil 
of  bitter  almonds,  hydrocyanic, 
benzoic,  formic,  acetic,  and  car- 
bonic acids.  Firia's  test :  Heat 
the  substance  with  a  few  drops 
of  concentrated  sulphuric  acid  in 
a  watch-glass  ;  when  the  solu- 
tion is  cold,  add  a  little  water 
and  a  few  morsels  of  chalk, 
when  there  will  be  effervescence  ; 
filter ;  evaporate  to  small  bulk, 
and  add  two  drops  of  a  neutral 
solution  of  perchloride  of  iron ; 
a  violet  colour  indicates  tyrosin. 
in  water  ;  add  several  drops  of  a  neutral  solution  of  mercuric  nitrate  ; 
boil,  and  a  rose-coloured  fluid  with  a  reddish  precipitate  indicates  tyrosin. 


Fig.  30. — Acioular  crystals  of  tyrosin.  a, 
Single  crystals  ;  b,  6,  smaller  and  larger 
groups  of  the  same. 

Hoffmann's  test:  Dissolve  substance 


91 


THE  CHEMISTRY  OF  THE  BODY 


4.  Creatin,  C^HgNgOo  +  HoO,  is  related  to  another  amide,  sarcosin, 
(methyl-glycocin,  or  amido-methyl-acetic  acid).  This  substance,  sarco- 
sin, united  to  cyanamide,  gives  creatin,  thus — 

CH..NH,        CH.J        CH,.N  "    "  " 


CO.  OH 

Glycocin  or  Methyl, 

.iinido-acetic  acid. 


CO.  OH 

Methyl  glycocoUe 
or  sarcosin. 


+     C.N 
I 
I 
NH, 

Cyanamide. 


CH.,.N 


C.NH 


CO.  OH    NHo 

Creatin. 


Another   view  is  that  it  is  related  to  urea,   in   which  one  atom  of 

hydrogen  is  replaced  by  sarcosin,  less  one  molecule  of  hydroxyl — 

/CH3 

/CH3 


NHo 

I 
CO 

I 
NH., 


CHo .  N 

I 
CO 


-H 


NH, 

I 
CO 


CH., .  N 


N CO 

I 
H 


\H 


Urea.       Sarcosin,  less  hydroxyl.  Creatin. 

This  vieAV  is  supported  liy  the  fact  that  creatin  boiled  vnth.  baryta  water 
yields  sarcosin  and  urea — 

C4H9N3O,    +    H,0    =    C3H7NO.    +     CON0H4 

Creatin.  Sarcosin.  Urea. 

Creatin  is  found  in  the  muscles,  nervous  tissues,  the  blood,  the 
liquor  amnii,  and  the  testicle,  but  not  in  glands.  It  appears  in 
the  form  of  colourless  rhombohedric  prisms 
(Fig.  31).  It  is  soluble  in  water,  almost  in- 
soluble in  alcohol;  its  solutions  are  neutral. 
By  oxidation,  creatin  gives  oxalic  and  carbonic 
acids  and  methyluramine,  C^H^-Ng.  Although 
found  in  the  muscles,  it  has  not  been  proved 
that  it  is  increased  in  amount  by  causing  the 
muscles  to  contract,  and  its  presence  appears 
to  depend  more  on  the  natiire  of  the  diet  than 
on  a  breaking  clown  of  the  proteid  matter  of 
the  muscles  during  activity.  An  animal  diet 
increases,  whilst  a  vegetable  diet  decreases  its  amount.  With  an 
animal  diet,  an  allied  substance,  creatinin,  into  which  creatin  is 
readily  transformed,  appears  in  the  urine,  but  it  has  been  held  that 
this  excess  of  creatinin  comes  from  the  creatin  in  the  animal  food. 

5.  Creatinin,  C^H-XgO,   closely   related    to   creatin,   is   also   related 
to    a  body  named    methylhydantoin,   being  transformed    into  it  and 
ammonia  when  heated  T\ath  baryta  water  to  100°  C. — 
CH2 .  N(CH3)  CH. .  N(CH3) 


Fig.  31.— Creatin. 


I         CO 

I      I 

CO  .  NH 

Methylhydantoin. 


C.NH 


CO  .  NH. 

Creatinin. 


THE  AMIDO-ACIDS. 


95 


It  is  readily  derived  from  creatin.      Thus 
"vvitli  hydrocMoric  acid,   or  even  when 
creatin  is  subjected  to  prolonged  boil- 
ing, it  parts  witli  water,  and   creatinin 
is  formed,  thus — 


when  creatin  is  heated 


C4H9N3O, 

Creatin. 


CiH^NaO   +   HoO 
Creatinin. 


Fig.  32.— Creatinin. 


Creatinin  forms  large,  brilliant,  colour- 
less prisms,  having  an  alkaline  taste 
(Fig.  32).  It  is  soluble  in  water  and 
alcohol,  scarcely  soluble  in  ether.  It 
has  a  strongly  alkaline  reaction.  Oxid- 
ized, it  yields  methyluramine,  C2H7N3. 
A  concentrated  solution  of  chloride  of 
zinc  (not  acid)  produces  a  finely  granu- 
lar precipitate,  or  groups  of  fine  needles 

or  prisms,  of  a  double  chloride  of  zinc  and  creatinin ;  this  chloride, 
treated  with  sulphide  of  ammonium,  reproduces  creatin  by  taking  an 

equivalent  of  water — 

CjHyKjO     +    H^O     =     C4H9N3O2 

Creatinin.  Creatin. 

Test. — A  solution  of  creatinin,  as  in  urine,  acidulated  by  nitric  acid,  gives 
with  phospho-molybdic  acid  a  yellow  crystalline  precipitate,  soluble  in  hot  nitric 
acid. 

The  transformation  of  creatin  into  creatinin  does  not  occur  in  the 
blood  (which  contains  no  creatinin),  and  it  would  appear  that  it  occurs 
in  the  kidneys,  as  there  is  always  creatinin  and  not  creatin  in  the 
urine.  Ligature  of  the  ureters,  however,  is  not  followed  by  the  appear- 
ance in  the  kidney  of  creatinin,  but  of  creatin,  pointing  to  the 
transformation  happening,  not  in  the  substance  of  the  kidney,  but 
in  the  urine.  As  to  the  possible  transformation  of  creatin  into 
urea,  there  is  conflicting  evidence.  Munk  found  that  the  administra- 
tion of  creatin  to  man  and  the  dog  was  followed  by  an  increase  in 
the  amount  oi  creatinin  in  the  urine,  and  also  by  an  increase  in  the 
amount  of  urea.  The  change  of  creatinin  into  lu-ea  was  supposed  by 
Oppler,  Zaleski,  and  others  to  occur  in  the  Iddney,  as  extirpation  of 
the  kidney  was  found  by  them  to  cause  not  an  increase  of  the  urea  in 
the  blood,  but  of  creatin  in  the  muscles.  On  the  other  hand,  if  the 
ureters  were  ligatiured,  urea  accumulated  in  the  blood  and  the  amount 
of  creatin  in  the  muscles  was  normal.  Similar  experiments  by  Voit  and 
Meissner,  and  by  Voit  and  Gscheidlen  have,  however,  given  negative 
results.  "V^Tien  one  considers  the  severe  nature  of  the  operations,  and 
the  impossibility  of  the  animals  surviving  for  more  than  a  few  hours,  it 


96 


THE  CHEMISTRY  OF  THE  BODY. 


is  not  surprising  tha  tresults  should  be  contradictory.  The  matter  then 
stands  thns — that  whilst  in  the  laboratory  by  various  methods  creatin 
can  be  decomposed  into  sarcosin  and  urea,  there  is  no  proof  that  this 
occui's  in  the  l)ody. 

6.  Taurin,  CoH^NSOy,  is  an  organic  body  related  to  isthionic  acid, 
or  sulphurous  acid  in  which  an  atom  of  hydrogen  is  replaced  by  a 
monatomic  radicle  oxyethylene  ((CH2)o.0H),  and  in  turn  the  replace- 
ment of  the  hydroxyl  in  isthionic  acid  by  NHo  produces  taurin,  thus  — 
SO., .  OH.,  CHo .  OH  CH., .  OH  CH., .  NH, 


CHo 


CH, 

I 

SO., .  OH 
Isthionic  acid. 


CH., 

I 
SO, .  OH. 

Tuurin. 


Sulphurous  acid.  Oxyethylene. 

"With  cholalic  acid,  taurin  forms  one  of  the  bile  acids,  taurocholic 
acid,  just  as  glycocin,  unites  with  the  same  acid  to  produce  glyco- 
cholic  acid.  Another  point  of  resemblance  between  glycocin  and 
taurin  is  that  cyanic  acid  combines  with  glycocin  to  form  hydantoinic 
acid,  whilst  cyanic  acid  with  taurin  leads  to  tauro-carbamic  acid,  thus — 
CH., .  NH,  CH., .  NH  .  CO 


CO.  OH 

Glycocin. 

CH, .  NH., 

I 
CH2 .  SO. , 

Taurin. 


OH 


CO  .  OH     NH, 

Hydantoinic  acid. 

CH2 .  HN .  CO 

I  I 

CH, .  SO, .  OH  .  NH, 

Tauro-carbamic  acid. 


Tauro-carbamic  acid  exists  in  the  urine  and  may  originate  by  the  union 
of  taurin  with  cyanic  acid.  Taiirin,  arising  from  the  decomposition 
of  taurocholic  acid,  is  found  in  small  amount  in  the  intestinal  canal  and 

faeces,  and  also  in  muscle,  in  the 
lungs,  in  the  urine  of  the  ox,  and 
in  the  liver  and  spleen  of  certain 
fishes.  Its  origin  is  unknown. 
From  the  small  amount  in 
the  faeces,  and  the  relatively 
large  amount  found  in  the 
liver,  it  is  probable  that  jDart  of 
the  taurin  is  decomposed  into 
simpler  substances.  As  potash 
splits  it  U2)  into  carbonate  of 
ammonia  and  the  sulphite  and 
acetate  of  potash,  it  has  been 
conjectured  that  the  alkalies  of 
the  bile  may  so  transform  it,  and  that  the  sulphates  of  the  mine  may 


Fig.  33. — Taurin.  a.  Six-sided  prisms  ; 
b.  Irregular  sheaf-like  masses  from  an 
impure  solution. 


THE  NITROGENOUS  ACIDS. 


97 


be  partly  derived  from  this  source.  Taurin  crystallizes  in  the  form  of 
colourless  six-sided  prisms  (Fig.  33).  It  is  soluble  in  water,  and  is 
insoluble  in  alcohol  and  in  ether. 

7.  Cystin,  CgH-NSO^,  is  amido-lactic  acid,  thus — 

CH„ .  OH  CH3 

"HS 


CH. 

I 

CO.  OH 

Lactic  acid. 


c  ■■ 

I 

CO 


^NHj 
OH 

Cystin. 


Fig.  34.— Cystin. 


It  is  found  as  a  constituent  of  a  rare  form  of 

urinary  calculus,   and   occasionally  in  the  urine, 

more  especially  of  the  dog.     Its  origin  is  unknown. 

It   forms   rhombohedric   or   hexagonal   colourless 

plates  (Fig.  34).     It  is  insoluble  in  water,  alcohol, 

and  ether,  but  is  soluble,  like  uric  acid,  in  ammonia,  in  the  mineral  acids, 

and  in  a  solution  of  oxalic  acid.     If  heated  on  a  silver  surface  with  a 

little  caustic  soda,  it  gives  a  brownish-black  spot  of  sulphide  of  silver. 

8.  Sarcosin,  CgH^NO^,  has  been  already  referred  to  in  treating  of 
ci-eatin,  and  we  have  seen  that  it  is  methyl-glycoUe,  C2H4(CH3)N'02.  It 
has  not  been  found  in  the  body,  but  it  may  be  obtained  by  heating 
creatin  with  baryta  water.  It  crystallizes  in  rhombohedric  colourless 
columns.  It  is  very  soluble  in  water,  less  so  in  alcohol,  and  not  at  all 
in  ether. 


Chap.  VII. -THE  NITROGENOUS  ACIDS. 


1.  Sulphocyanic  Add,  CNHS,  united  to  potassium  or  sodium  to  form 
a  sulphocyanide,  is  almost  invariably  found  in  the  saliva,  and  it  has 
occasionally  been  found  in  the  urine,  in  milk,  and  in  the  blood.  It  may 
be  detected  by  giving  a  red  colour  (sulphocyanide  of  iron)  with  a  solu- 
tion of  perchloride  of  iron.  Some  have  supposed  that  it  may  originate 
from  the  decomposition  of  carious  teeth,  but  it  has  been  found  where 
this  condition  did  not  exist. 

2.  Uric  Acid,  CgH^N^Og,  is  one  of  the  most  important  bodies  of  this 
group,  inasmuch  as  it  is  related  to  a  number  of  nitrogenized  substances, 
often  met  with  in  the  solids  and  fluids.  Much  diversity  of  view  still 
exists  as  to  its  chemical  nature.  Baeyer  regards  it  as  formed  by  the 
union  of  a  radicle  cyanamide  with  tartronic  or  oxymalonic  acid — 

CO .  OH         fNH.,  CO  .  NH  .  CN 

I  2J     I    "  I 

CH.OH     +  [CN      =      CH.OH  +     2HoO 

CO  .OH  CO  .  NH  .  CN 

Tartronic  acid.     Cyanamide.  Uric  acid. 

I.  G 


98 


THE  CHEMISTRY  OF  THE  BODY 


or,  tAvo  molecules  of  bydroxyl  in  tartronic  acid  are  replaced  by  two 
cyanamides,  which  each  lose  an  atom  of  hydrogen,  and  these,  Avith  the 
molecules  of  hydroxyl,  form  Avater.  Another  vieAv  put  forAA^ard  by 
Medicus  is  to  consider  uric  acid  as  containing  a  nucleus  of  3  atoms  of 
carbon,  and  that  this  Avith  tAA^o  residues  of  urea  forms  uric  acid  or  a, 
di-iu^eide,  thus — 


—CO 

I 
C— 

II 

— c— 

Nucleus. 


CO 
NH 

Residue  of  urea. 


NH— CO 

I  I 

CO      C— NH\ 

I  II  / 

NH— C— NH  / 

Uric  acid. 


CO. 


This  suggests  the  relationshij:)  of  a  number  of  the  bodies  allied  to 
uric  acid,  such  as  alloxan,  urea,  parabanic  acid,  allantoin,  oxaluric  acid, 
xanthin,  sarcin,  and  guanin,  thus — 

NH— CO  NH,  NH— CO  NH-C  .  OH 

I  I     ■  I 

CO— CO  CO  CO 


NH— CO 

Alloxan. 

NH., 

I 
CO 


NH. 

Urea. 

CO.  OH 


NH— CO 

Parabanic  acid. 


NH- 

CO 

NH- 


-C— NH- 

Allantoin. 


CO— NH, 


NH-CO 


NH— CO 

Oxaluric  acid. 


CO      C— NH 

!        II 

NH— C  —  N 

Xanthin. 


CH 


NH— CO 


CH 

11         II 
N—  C  - 

Sarcin 


NH. 

-N- 


NH- 

I 
NH  =  C 


CH 


I^H— C  - 

Guanin 


CO 

I 

C— NH 

II 

N- 


CH 


Most  oxidizing  substances  coiiA^ert  uric  acid  into  alloxan  or  parabanic  acid : 
and  AA^hen  boiled  AAdth  water  and  peroxide  of  lead,  it  yields  allantoiTi. 
AVhen  oxidized  in  the  presence  of  Avater  it  giA^es  up  tAA'o  of  its  hydrogen 
atoms  to  the  oxidizing  agent,  while  the  dehydrogenized  residue  (dehy- 
duric  acid)  reacts  A\dth  AA'ater  to  form  mesoxalic  acid  and  urea — 


CsH^N^Oa 
Dehyduric  acid. 


4HoO 


CsH.Os 

Mesoxalic  acid. 


2CN2H4O 

Urea. 


Dilute  nitric  acid  acts  upon  uric  acid  and  produces  alloxan,  and  this 
when  heated  AA-ith  baryta  AA^ater  is  resoU'ed  into  mesoxalic  acid  and  urea — 

\-        2H„0 


C^HoN^Og 

Dehydm-ic  acid. 
C^NoH^Oi 

Alloxan. 


HoO 


CiNoH,04 

Alloxan. 
Slesoxalic  acid. 


CNoH.O 

Urea. 

CNjH^O 

Urea. 


Alloxan  may  be  regarded  as  a  mon-ureide  of  mesoxalic  acid  formed  by 


THE  NITROGENOUS  ACIDS.  99 

the  union  of  one  molecule  of  the  acid  with  one  molecule  of  urea,  less 
two  of  water,  and  formed  thus — 

C3H0O5  +  CNoHiO     -    2H2O  r=  C4N2H2O, 

Mesoxalic  acid.  Ureiu  Alloxan. 

Again,  the  hypothetical  dehyduric  acid  is  a  di-urekle  of  mesoxalic 
acid,  that  is,  it  is  formed  by  the  union  of  one  molecule  of  mesoxalic  acid 
with  two  molecules  of  urea,  less  four  molecules  of  water,  thus — 

C3H2OS        +        2(CH4N20)  -  4HoO        =        C3H2N4O3 

Mesoxalic  acid.  Urea.  Dehyduric  acid. 

By  hydrogenizing  mesoxalic  acid,  tartronic  acid  is  produced;  and  by 
hydrogenizing  alloxan,  we  obtain  another  comjDOund  known  as  dialuric 
acid.  These  bodies,  tartronic  acid  and  diakmc  acid,  bear  the  same  rela- 
tion to  uric  acid  as  mesoxalic  acid  and  lurea  bear  to  dehyduric  acid, 

thus — 

C3H2O3  C4N,H,04  CgN4H203 

Mesoxalic  acid.  Alloxan.  Dehyduric  acid. 

C3H40g  C,N,H,0,  CsN.H.Oj 

Tartronic  acid.  Dialuric  acid.  Uric  acid. 

Thus  we  have  three  groups  of  bodies  related  to  uric  acid  :  (a)  an-ureides, 
non-nitrogenous  acids,  such  as  tartronic  and  mesoxalic  acids;  (h)  mon- 
ureides,  consisting  of  a  residue  of  the  acid  added  to  one  residue  of  urea, 
such  as  dialuric  acid  and  alloxan;  and  (c)  di-ureidcs,  consisting  of  a 
residue  of  the  acid  added  to  two  residues  of  urea,  such  as  uric  acid  itself. 
It  is  important  also  to  observe  the  origin  of  other  bodies  belonging  to 
these  groups.  Thus  mesoxalic  acid,  the  most  complex  non-nitrogenous 
product  that  can  be  obtained  by  the  oxidation  of  uric  acid,  is  one  of  a 
series  of  an-ureides,  each  of  which  contains  one  CO  group  more  than 

the  preceding,  thus  — 

CH2O3    Carbonic  acid. 
C2H2O4  Oxalic  acid. 
CoHoOj  Mesoxalic  acid. 

Acted  on  by  nascent  oxygen,  mesoxalic  acid  loses  its  excess  of  CO  and 
becomes  oxalic  acid,  thus :  CgHgOg  +  0  =  CO2  +  C2H2O4.  Hence  when  uric 
acid  is  oxidized  beyond  the  point  of  producing  mesoxalic  acid,  oxalic  acid 
may  be  formed,  and  this  may  conjugate  with  one  mol.  of  urea  to  form 
a  mon-ureide,  parabanic  acid,  or  with  two  mol.  of  urea  to  form  a  di- 
ureide,  mycomelic  acid.  If  the  oxidation  of  uric  acid  proceeds  further 
than  the  oxalic  acid  stage,  carbonic  acid  is  formed,  and  this  is  also  theo- 
retically capable  of  forming  ureides.  Thus  allophanic  acid  is  the  mon- 
ureide  of  carbonic  acid,  but  no  di-ureide  exists.  Alloxan,  the  mon-ureide 
of  mesoxalic  acid,  is  formed  from  mesoxalate  of  urea  by  the  elimination 
of  two  mol.  of  water,  but  if  only  one  mol.  of  water  is  removed,  a 


100 


THE  CHEMISTRY  OF  THE  BODY. 


related  body,  alluxanic  acid,  is  produced.  Similarly,  oxalic  acid  yields 
two  mon-ureides,  parabanic  acid  and  oxahiric  acid.  The  relation  of  these 
bodies  is  seen  in  the  following  table,  modified  from  that  given  by 
Odling.     {Lectures  on  Animal  Cheinistri/,  p.  133.) 

Di-uroides. 


An-ureidos. 
CHoO.  Carbouic. 
CMjSi  Glyo.xalic. 
CM.fii  Oxalic. 


C.H4O4  :Malonic. 
C^HjOg  Tartronic. 
C3BUO5  Mesoxalic. 


Mon-ureides. 
C0N0H4O3  Allophanic. 
CgN^.HjO^  Lantanuric. 
C3N.JH4O4  Oxaluric. 
CgNoHoO^  Parabanic. 

C4N2H4O3  Barbituric. 
C4N0H4O4  Dialuric. 
C4N',Ho04  Alloxan. 


C4N4H6O:,  AUautoin. 


€5X41140  Hypoxanthin. 
GgN4H402  Xanthin. 
C5N4H4O3  Uric  acid. 


The  substance  termed  alloxantin  is  foi'med  by  the  union  of  two  consecu- 
tive mon-ureides,  dialuric  acid  and  alloxan,  ^Wth  the  elimination  of 
Avater,  thus  — 

C4N0H4O4  +  C4N0H0O4  -  H,,0= C8N4H4O,. 


Dialuric  acid.      Alloxan. 


Alloxantin. 


It  -will  also  be  seen  that  xanthin  is  the  di-ureide  of  barbituric  acid, 
which  again  is  the  mon-ureide  of  malonic  acid,  and  this  in  turn  can  be 
obtained  from  tartronic  acid  by  deoxidation.  Closely  related  to  xanthin 
is  hypoxanthin.  Uric  acid  deoxidized  by  sodium  amalgam  yields  a 
mixture  of  xanthin  and  hypoxanthin,  and  hypoxanthin  may  be  con- 
A-erted  into  xanthin  by  oxidation  with  nitric  acid. 

Uric  acid  is  found  in  the  urine,  either  in  the  free  condition  to  a  very 
^,,-— :^  small  extent  or  in  the  form  of  the  urates  of 

^^^^^^ss;^^   . '^^     potash  and  soda,  perhaps  the  most  common 

forms  of  urinary  deposit.  The  daily  amount 
eliminated  by  an  adult  man  Avith  a  mixed 
diet  is  from  '5  to  1  gram.;  -with  a  vegetable 
diet  it  may  fall  to  '3  gram.,  and  with  a  rich 
animal  diet  it  may  amount  to  as  much  as  1  '5 
gram.  It  also  is  met  Avith  in  urinary  calculi 
and  in  the  chalky  deposits  in  the  joints  of 
gouty  persons.  Traces  also  are  found  in  the 
blood,  kidneys,  spleen,  lungs,  brain,  and 
muscular  tissue.  It  forms  a  large  part  of 
the  excrement  of  birds  and  of  reptiles. 

Pure  uric  acid  crystallizes  in  colourless 
rhombic  rectangular  or  hexagonal  plates,  or 
in  rectangular  prisms.  "WTien  obtained  from 
urine,  it  is  coloured  more  or  less  by  the  urinary  pigment,  and  forms 
rhombs,  lozenges,  or  rectangular  prisms,  and  these  are  grouped  so  as  to 


Fig.  35. — Uric  acid,  a,  a,  Rhombs 
and  rectangular  prisms ;  b,  forms 
from  human  urine  ;  c,  dumb-bell 
crystals.  In  right  hand  corner, 
rosette. 


THE  NITROGENOUS  ACIDS.  101 

form  rosettes,  barrels,  or  dumb-bell  like  forms.  (See  Fig.  35.)  Uric 
acid  is  tasteless  and  inodorous.  Its  solubility  is  small  as  it  requires  for 
its  solution  1,900  parts  of  cold  water  and  15,000  parts  of  hot  water; 
it  is  insoluble  in  alcohol  and  ether.  Its  solutions  are  feebly  acid.  It 
is  dibasic. 

There  are  several  well  known  salts  of  uric  acid. 

(a)  Urates  of  soda.  These  form  the  chief  part  of  the  deposit  of  urates 
commonly  found  in  urine  and  are  readily  recognized  by  their  disappearance 
on  heating.  There  are  two  urates  of  soda — the 
neutral  salt,  CgHgN^OgNa^,  which  forms  nodular 
masses,  and  the  acid  urate,  CgHgN^OgNa,  which  is 
usually  amorphous  and  rarely  crystallizes  in  urine. 
The  latter  is  soluble  in  1,200  parts  of  cold  water  and  in 
25  parts  of  boiling  water.  The  chalky  deposits  in  the 
joints  of  gouty  persons  are  almost  entirely  composed 
of  this  salt,  and  from  these  it  may  be  obtained  in 
forms  represented  in  Fig.  36. 

■^  ^  .  Fig.  36.— Acid  urate  of 

(o)  Urates  of  potash  correspondina;  to  those  of  soda  soda,  a,  Needles,  usually 

T  ,•:  .^  *.  ,  .  aggregated ;  6,  6,  spher- 

may   be  made  by  saturating  a  solution  of  potassium  oidai  masses. 
hydrate  with  uric  acid,  when  they  may  be  crystallized  as  fine  needles, 
but  they  do  not  often  occur  in  urinary  sediments.  i^  V  ^ 

(c)  Acid  urate  of  ammonia,  Q>^.^^.JiJ^^^,  is  found     '^    ^ 
in   alkaline   urine,  either  as  a   pinkish  amorphous 
powder  or  in  the  form  of  globular  masses  having 
little  spicules  proceeding;  from  them  (Fia;.  37).     The 

^     .     .  -,  \      &  /  Pjg_  37._xjrate  of 

neutral  salt  is  unknown.  ammonia. 

{d)  Acid  urate  of  lime,  (G^.^^O^.^G^i,  occurs  in  urinary  sediments 
and  calculi,  and  appears  in  the  form  of  fine  needles. 

(e)  Acid  urate  oflithia,  CgHgN^OgLi,  is  the  most  soluble  salt  of  uric  acid. 
"It  may  be  artificially  prepared  by  dissolving  uric  acid  in  a  warm 
solution  of  lithium  carbonate.  It  crystallizes  in  needles,  which  dissolve 
in  60  parts  of  water  at  50°  C,  and  do  not  separate  when  the  solution  is 
cooled."     (Witthaus,  Manual  of  Chemistry.) 

Tests  for  Uric  Acid. — (1)  Murexide  test:  Put  a  little  of  the  substance 
to  be  examined  on  a  white  porcelain  plate  or  lid,  add  two  drops  of 
nitric  acid,  heat  and  evaporate  till  dry ;  if  the  substance  is  uric  acid, 
it  dissolves  in  nitric  acid,  and  gives  on  evaporation  a  yellow  or  reddish- 
yellow  residue,  which  becomes  reddish-purple  by  adding  a  drop  of 
caustic  ammonia,  and  bluish-violet  with  soda  or  potash.  The  purple 
colour  is  readily  brought  out  by  bringing  a  glass  rod  dipped  in  ammonia 
solution  near  the  residue  after  evaporation.  (2)  Dissolve  the  substance 
to  be  examined  in  a  few  drops  of  solution  of  caustic  soda,  and  filter ;  add 


102  THE  CHEMISTRY  OF  THE  BODY. 

to  the  liquid  chloride  of  ammonium  in  excess,  and  there  will  be  a  precip- 
itate of  urate  of  ammonia  which,  by  the  addition  of  hydrochloric  acid, 
yields  crystals  of  uric  acid.  (3)  The  microscopic  examination  of  the 
crystals  so  as  to  determine  their  form.  (4)  Garrod's  test :  To  detect  uric 
acid  in  serum,  place  about  2  c.c.  of  the  serum  in  a  flat  watch-glass  and 
acidulate  with  acetic  acid ;  a  fine  fibril  of  linen  thread  is  placed  in  the 
liquid,  which  is  set  aside  and  allowed  to  evaporate  for  two  or  three 
hours ;  the  fibril  is  then  examined  microscopically  when  it  Avill  be  found 
to  have  crystals  of  uric  acid  adherent  to  it. 

The  ori[jin  of  u.ric  acid  is  still  douljtful.  Its  relationship  to  guanin, 
sarcin,  and  xanthin  has  already  been  pointed  out.  Guanin  and  sar- 
cin  have  been  changed  into  xanthin,  but  the  latter  has  not  been  con- 
verted into  uric  acid.  Uric  acid,  however,  reduced  by  sodium  amalgam, 
has  yielded  sarcin  and  xanthin,  and  the  ultimate  products  of  the 
oxidation  of  all  four  bodies  are  the  same,  namely,  parabanic  acid,  oxaluric 
acid,  and  urea.  These  four  bodies — guanin,  sarcin,  xanthin,  and  uric 
acid — therefore,  probably  represent  four  stages  of  oxidation,  of  which 
uric  acid  is  the  last. 

Uric  acid  forms  the  principal  product  of  the  decomposition  of  nitro- 
genous matters  in  animals  so  different  as  birds  and  reptiles.  In  the 
bird  there  is  rapid  oxidation  and  a  high  temperature,  while  the  reverse 
conditions  exist  in  the  reptile,  and  still  the  chief  nitrogenous  substance 
in  the  excrements  of  both  classes  is  uric  acid,  a  fact  for  which  no  satis- 
factory explanation  can  be  offered.  Even  urea  in  the  bird  appears  to  be 
changed  into  uric  acid,  as  it  has  been  found  that  the  ingestion  of  urea  by 
fowls  is  followed  by  an  increased  elimination  of  uric  acid.  On  the  other 
hand,  the  ingestion  of  sarcosin  by  fowls  diminishes  the  amount  of  uric 
acid,  and  in  other  animals,  inhalations  of  oxygen  or  of  protoxide  of  nitro- 
gen, the  administration  of  sulphate  of  quinine,  and  a  vegetable  diet,  also 
diminish  it.  Quinic  acid  and  benzoic  acid  and  an  animal  diet  increase 
the  amount  of  uric  acid  eliminated. 

Further,  it  is  supposed  that  a  portion  of  the  uric  acid  formed  is 
eliminated  as  such,  while  another  portion  is  transformed  by  oxidation 
into  other  substances.  Thus  it  may  readily  be  changed,  first  into 
alloxan,  then  into  parabanic  acid,  then  into  oxaluric  acid,  then  into 
oxalic  acid  and  urea,  and  ultimately  into  carbonic  acid  and  water, 

thus — 

(1)  C5H4N4O.  +  H,0  +  0  =  C4H2N,04  +  N0H4CO. 

Uric  acid.  Alloxan.  Urea. 

(2)  C4H2N,04  +  0  =  C3H2N0O3  +  CO.. 

Alloxan.  Parabanic  acid. 

(3)  CsH^N^Os  +  H,0  =  C3H4N2O4. 

Parabanic  acid.  Oxaluric  acid. 


THE  NITROGENOUS  ACIDS.  103 

(4)  C3H4N2O4  +  HoO  =  CN^H^O  +  C2H2O4. 

Oxaluric  acid.  Urea.  Oxalic  aaid. 

(5)  C2H2O4  +  0  =  2C0.  +  H2O. 
Oxalic  acid. 

Another  view  is  that  uric  acid  by  oxidation  is  changed  into  allantoin 
and  that  this  substance  is  resolved  by  successive  stages,  in  which  new 
compounds  appear,  into  urea  and  parabanic  acid,  the  latter  being  then 
split  up  into  urea,  carbonic  acid,  and  water,  as  has  already  been  shown, 
thus — 

(1)  C5H4N4O3  +  H^O  +  0  =  C4H6N4O3  +  CO2. 

Uric  acid.  Allantoin. 

(2)  C4HSN4O3    +    HoO    =    CN2H4O    +    C3H4N0O3. 

Allantoin.  Urea.  Allanturic  acid. 

(3)  2{C3H4N203)  =   C3H2N2O3  +   CsHgN^Oa. 
Allanturic  acid.       Parabauic  acid.    Hydaoto'inic  acid. 

Allanturic,  parabanic,  and  hydantoinic  acids  have  not  been  found  in  the 
body,  but  allantoin  is  met  with  in  the  urine  of  the  newly  born.  Fur- 
ther, Salkowski  has  found  that  the  ingestion  of  uric  acid  by  dogs  is 
followed  by  the  appearance  of  allantoin  in  the  urine.  The  evidence 
both  from  chemical  considerations  and  the  observation  of  some  pheno- 
mena of  disease  is  in  favoiu"  of  the  view  that  a  portion  of  uric  acid 
may  be  resolved  into  urea,  and  that  this  transformation  is  aided  by 
active  oxidations. 

The  substances  specially  related  to  uric  acid  are  the  following — 

(1)  Guanin,  C5H5N5O,  has  been  found  in  the  liver  and  pancreas.  It 
is  a  white  or  yellowish,  amorphous,  odourless,  tasteless  substance,  almost 
insoluble  in  water,  alcohol,  and  ether,  but  easily  soluble  in  acids  and 
alkalies.  Evaporated  on  a  bit  of  platinum  foil  with  a  drop  of  fuming 
nitric  acid,  it  gives  a  yellowish  residue  which  becomes  red  on  the  addi- 
tion of  a  drop  of  caustic  soda,  and  gives  a  purple  colour  on  heating. 
Derived  from  the  splitting  up  of  albuminous  matters,  it  probably  gives 
origin  to  xanthin  and  ultimately  to  urea. 

(2)  Sarcin  or  Hypoxanthin,  C^H^N^O,  has  been  found  in  the  spleen, 

pancreas,   supra-renal    capsules,  muscles,  liver,   marrow  of  bone,  the 

urine,    the  liver  in  acute  yellow  atrophy,   and   the  blood  and  urine 

of  leucocythaemia.     It  occurs  in  the  state  of  nodular  masses  formed  of 

fine  colourless  needles,  soluble  in  300  parts  of  cold  and  78  parts  of 

boiling  water.     (Witthaus.)     Oxidized  by  nitric  acid  it  gives  xanthin, 

thus — 

C5H4N4O  +  0  =  C5H4N4O0. 

Hypoxanthin.  Xanthin. 

(3)  Xanthin,  C^^HJ^^O^,  sometimes  termed  xanthic  oxide,  is  found  in 
a  rare  form  of  urinary  calculus,  in  human  urine  after  the  use  of  sulphur 


104.  THE  CHEMISTRY  OF  THE  BODY. 

baths  and  inunctions,  and  in  the  pancreas,  spleen,  liver,  thymus,  and 
brain.  It  is  a  pale  yelloAv  amorphous  powder,  slightly  soluble  in  cold 
water,  insoluble  in  alcohol  and  ether,  and  soluble  in  ammonia.  Dissolved 
in  a  drop  or  two  of  nitric  acid  and  evaporated,  a  yellowish  residue  is 
left  which  turns  reddish-yellow  on  the  addition  of  a  drop  of  solution  of 
caustic  potash,  and  violet-red  on  being  heated.  Calculi  of  xanthin  vary 
in  size  from  that  of  a  pea  to  that  of  a  jngcon's  egg.  They  are  hard, 
brownish-yellow,  smooth,  shining,  and  show  well-defined  concentric 
layers.     Their  broken  surface  assumes  a  waxy  polish  when  rubbed. 

(4)  AUanioin  and  oxaluric  acid  have  been  described.     (See  p.  88.) 

(5)  Caniin,  C-HgN^O.,  -t-  HgO,  occurs  in  the  form  of  chalky  crystals, 
readily  soluble  in  warm  water  but  insoluble  in  alcohol  and  ether.  It  is 
intimately  related  to  sarcin  and  it  may  be  considered  as  a  compound  of 
that  body  and  acetic  acid,  thus — 

CgfljN^O      +      C2H4O2      =      C,H8N403 

Sarcin.  Acetic  acid.  Carnin. 

It  may  be  obtained  from  extract  of  meat.  Doses  of  from  -05  to  '2 
gramme  exert  a  slightly  depressing  influence  on  the  heart. 

3.  Hippuric  acid,  C9H9NO3,  or  benzyl-glycocol,  is  glycocolle  in  which 
one  atom  of  hydrogen  has  been  replaced  by  the  radicle  benzyl,  C^.Hg.CO, 

thus — 

CH,  -  NH„  CH, .  NlCfiHg .  CO)H 

I     '  '  I     " 

CO .OH  CO .  OH 

Glycocolle.  Hippuric  acid. 

It  is  isomeric  with  acetamidobenzoic  acid,  C.^Hg(C\,H30)NOo.  AVhen 
heated  with  the  mineral  acids,  or  the  alkalies,  or  when  influenced  by 
certain  ferments,  such  as  that  of  decomposing  urine,  hippuric  acid  is 
converted  into  glycocolle  and  benzoic  acid — 

C9H9NO3     +     H2O     =     C2H5NO,     +     C^HgOo 

Hippuric  acid.  Glycocolle.  Benzoic  acid. 

Hippuric  acid  is  a  constant  constituent  of  the  urine  of  herbivora  and  of 
human  urine  in  the  form  of  hippurate  of  soda  (CgHgNaNOg .  H2O) 
or  of  lime  Ca(C9HgN03)2  •  SH^O.  Only  a  very  small  amount  exists  in 
urine  in  the  free  state.  It  crystallizes  in  transparent,  colourless  prisms 
(Fig.  38).  Bj^  slow  evaporation  from  dilute  solutions,  crystals  arc 
obtained  similar  to  those  of  the  triple  phosphate  of  ammonia  and 
magnesia.  (Frey.)  It  is  soluble  sparingly  in  water,  and  more  readily 
in  hot  alcohol  or  ether.  It  dissolves  unchanged  in  hydrochloric  acid, 
and  on  boiling  the  solution  it  is  converted  into  benzoic  acid  and  gly- 
cocolle.    The  folloAving  are  the  tests  by  which  hippuric  acid  may  be 


THE  NITROGENOUS  ACIDS. 


105 


Fig.  3S. — Hippuric  acid,  a,  a,  Prisms  ; 
6,  crystals  like  those  of  the  triple 
phosphate. 


readily  distinguislied  :  (1)  Lucke's  test:  Evaporate  with  excess  of  nitric 
acid ;  heat  residue  strongly,  and  an 
odour  of  hydrocyanic  acid  may  be  per- 
ceived. (2)  It  gives  a  brown  precip- 
itate with  ferric  chloride.  (3)  Heated 
with  lime,  it  gives  off  benzin  and  am- 
monia. Hippuric  acid  may  be  formed 
from  matters  supplied  in  the  food  or 
from  the  decomposition  of  albuminous 
matters  in  the  body.  It  is  well  known 
that  it  appears  in  the  urine  after  the 
administration  of  benzoic  acid,  or  of 
benzoates,  or  of  articles  of  food  con- 
taining benzoic  acid,  and  this  can  be 
explained  by  assuming  that  it  unites 
with  glycocin,  with  the  loss  of  a  molecule  of  water,  thus — 
CyHgOa    +    C3H5NO2     -     H2O    =    C3H9NO3 

Benzoic  acid.  Glycocin.  Hippuric  acid. 

Marchand,  after  taking  30  grains  of  benzoic  acid,  found  39'2  grains  of 
hippuric  acid  in  the  urine.  It  is  also  found  in  the  urine  after  the 
ingestion  of  cinnamic  and  mandelic  acids.  It  would  appear  also  that 
this  reaction  is  the  type  of  others.  Thus,  such  aromatic  acids  as 
toluilic,  anisic,  and  salicylic  acids  unite  in  the  body  with  glycocin  to 
form  toluric,  anisuric,  and  salicyluric  acids.  Quinic  acid  is  changed 
into  hippuric  acid  in  the  organism,  probably  first  into  benzoic  acid. 
The  large  amount  of  hippuric  acid  in  the  urine  of  herbivora  has  not 
received  a  satisfactory  explanation.  In  this  case  it  is  not  derived  from 
benzoic  acid  or  quinic  acid,  as  both  of  these  substances  are  usually 
absent  from  the  food  of  herbivora.  Shepard  and  Meissner  have  main- 
tained that  it  is  derived  from  the  cuticular  matter  of  plants,  and  from 
cellulose,  and  they  state  that  the  amount  of  hippuric  acid  is  increased 
by  a  diet  rich  in  such  matter,  such  as  the  straw  of  cereals,  whilst  it  is 
diminished  by  a  diet  of  potatoes,  carrots,  or  beet-root,  substances  rich 
in  starch  but  containing  little  of  the  cuticular  matter.  These  state- 
ments have  not  been  unquestioned,  and  it  has  been  pointed  out  that 
much  may  depend  on  the  kind  of  animal,  as  the  straw  of  oats  increases 
hippuric  acid  in  the  urine  of  the  ox,  but  not  in  that  of  the  rabbit. 
(See  Hippuric  acid.  Watt's  Diet,  of  Chem.,  2nd  supplement,  p.  647.) 

As  hippuric  acid  is  always  found  in  small  quantity  in  the  urine  even 
with  an  animal  diet,  it  has  been  supposed  that  it  may  originate  from 
the  decomposition  of  proteid  matter.  It  is  conceivable  that  such  a 
decomposition  may  give  rise  to  benzoic  acid  and  glycocoUe ;  and,  in 


106  THE  CHEMISTRY  OF  THE  BODY. 

that  case,  hippuric  acid  Avould  probably  be  formed.  This  union  may 
occur  in  the  liver  (Kiihne  and  Hallwachs),  or  in  the  tissues  (Bunge  and 
Schmiedeberg),  or  in  the  kidneys  (Shepard  and  Meissner) — most  pro- 
bably in  the  latter.  Thus,  it  has  been  found  that  after  ligature  of  the 
renal  vessels  in  the  dog,  no  hippuric  acid  appears  in  the  liver  or  in  the 
tissues  after  the  injection  of  benzoic  acid.  Again,  Bunge  and  Schmiede- 
berg have  found  that  when  blood  containing  glycocolle  and  benzoic 
acid  is  passed  through  a  kidney  by  an  artificial  circulation,  hippuric 
acid  appears  both  in  the  blood  returning  from  the  kidney  and  in  the 
fluid  that  in  these  circumstances  may  exude  from  the  ureter.  No 
definite  information  exists  as  to  the  substance  in  the  blood  that  thus 
yields  hippuric  acid.  Coloured  blood  corpuscles  and  oxygen  are  neces- 
sary. Some  have  supposed  that  it  may  arise  from  the  oxidation  of 
tyrosin ;  and  others,  that  a  substance  exists  which  may,  in  certain 
conditions,  become  urea,  and,  in  other  conditions,  hippuric  acid. 
(Beaunis.) 

4.  Inosinic  or  Inosic  acid,  CjoHj^lST^Oj^^,  is  a  substance  found  in  the 
mother  liquor  of  the  preparation  of  creatin  from  muscle  juice.  It  is 
uncrystallizable  ;  it  is  readily  soluble  in  water,  and  alcohol  precipitates 
it  from  its  aqueous  solution.  The  nature  and  properties  of  this  sub- 
stance have  not  been  fully  investigated. 

5.  Cryptophanic  acid,  C-^qH-^^ .fi^^,  is  said  by  Thudichum  to  exist  in 
human  urine.  It  is  an  amorphous,  gummy  mass,  transparent  and 
nearly  colourless,  readily  soluble  in  water,  and  less  soluble  in  alcohol. 
It  is  said  to  have  feeble  acid  properties.  (See  Journal  of  Chemical  Society 
[2]  viii.  132  ;  see  also  Beaunis,  Physiologie,  vol.  i.  p.  138.) 

6.  Bile  acids.  The  bile  of  most  animals  contains  the  sodium  salts  of 
amido-acids  of  complex  constitution.  Of  these  acids,  two  are  found  in 
the  bile  of  man,  namely,  glycocholic  acid  and  taurocholic  acid,  and 
these  in  turn  are  related  to  two  others,  cholalic  acid  and  choloidic  acid. 

(a)  Glycocholic  add,  C^^^H^gNOg,  the  cholic  acid  of  Gmelin,  exists  in 
human  bile  as  glycocholate  of  soda  in  amounts  varying  according  to  diet. 
An  animal  diet  diminishes  the  quantity,  while  a  vegetable  diet  has  the 
contrary  effect.  It  is  therefore  readily  found  in  ox  bile  and  in  the 
bile  of  herbivora  generally,  and  the  amount  is  smaller  in  that  of 
carnivora.  When  obtained  from  ox  bile,  it  forms  brilliant,  colourless, 
transparent  needles,  sparingly  soluble  in  cold  water,  readily  soluble  in 
hot  water  and  in  alcohol,  glycerine,  and  acetic  acid,  whilst  it  is 
almost  insoluble  in  ether.  The  taste  is  at  first  sweet,  and  afterwards 
intensely  bitter.  The  alcoholic  solution  is  dextro-rotatory  when 
examined  with  the  polariscope,  [«]d=  +29°.  By  the  action  of  potash, 
baryta,  dilute  sulphuric  acid,  or  dilute  hydrochloric  acid,  it  takes  up  a 


TEE  NITROGENOUS  ACIDS. 


107 


molecule  of  water,  and  th^ri  is  decomposed  into  glycocin  and  cholalic 
acid,  thus — 

Glycocholic  acid.  Cholalic  acid.  Glycocin. 

Sodium  glycocholate,  CggH^gNaNOg,  crystallizes  in 
stellate  needles  (Fig.  39),  is  readily  soluble  in  water, 
less  so  in  alcohol,  and  is  insoluble  in  ether.  With 
polarized  light  [a]D=  +  25°-7.  Hamersten  states 
that  the  glycocholic  acid  of  man  differs  slightly 
from  that  of  the  ox.  The  bile  of  sea  fishes  con- 
tains the  glycocholates  and  taurocholates  of  potash, 
not  of  soda,  and  chiefly  in  the  form  of  the  soda 
salt. 

(h)  Taurocholic  acid,  C26H4r,N07S,  exists  in 
human  bile  and  in  the  bile  of  carnivora ;  in 
small  amount  in  the  bile  of  herbivora.  It  is  easily  obtained  from  dog's 
bile,  in  the  form  of  silky  needles,  deliquescent,  and  readily  changed 
into  an  amorphous  resinous  mass.  It  is  soluble  in  water  and  alcohol, 
forming  intenselj^  bitter  solutions.  The  alcoholic  solution  gives  with 
polarized  light  [a]D=  +  24°"5.  Barium  hydrate  and  acids  give  the 
following  decomposition — 

C^gH^^NO^S     +     HoO     =     C24H40O5     +     C^H^NOgS 
Taurocholic  acid.  Cholalic  acid.  Taurin. 

The  same  decomposition  occurs  in  the  presence  of  putrefying  material, 


Fig.  39.— Glycocholate 
of  soda. 


and  in  the  intestine.  (Witthaus.)  TcmrocJwlate  of  soda,  C2(; 
is  soluble  in  alcohol  and  in  water,  and  is  very 
difficult  to  crystallize.  When  the  glycocholates 
and  taurocholates  exist  together  in  an  aqueous 
solution,  they  may  be  separated  by  dilute  sulphuric 
acid  and  a  small  quantity  of  ether,  which  pre- 
cipitates glycocholic  acid  alone. 

(c)  Cholalic  acid,  C24H4(jO;;,  the  result  of  the  de- 
composition of  the  conjugate  bile  acids,  as  already 
explained,  is  found  in  the  intestines  and  faeces  in 
the  form  of  large,  shining,  deliquescent  crystals 
(Fig.  40),  slightly  soluble  in  water,  and  readily 
soluble  in  alcohol  and  ether.  With  polarized  light, 
[a]  jj  =  -f  35°.^     By  boiling  with  acids  or   heated  to 


H^^NaNO^S, 


Fig.  40. — Cholalic  acid. 


200°   C,    cholalic 


^  Hoppe-Seyler  gives  for  cholic  acid  +aq.,  31°"2  ;  for  cholic  acid  alone,  50° "2  5 
for  sodium  chelate  dissolved  in  alcohol,  31°'4 ;  potassium  chelate,  30° '8;  for 
sodium  chelate  in  water,  26°;  and  for  potassium  chelate,  25°.  (Jl.  for  Cliem.  Ixxxix. 
257  ;  Bull.  Soc.  Chem.  v.  622,  quoted  in  Watt's  Diet,  of  Ghem.  vol.  vi.  p.  342. 


108  THE  CHEMISTRY  OF  THE  BODY. 

acid  may  lose  one  molecule  of  water,    and  become    {d)  choloidic  acid, 
or  (e)  dyslysin.     Thus — 

C,4H,oO,,        -  H,0        =        C,,4H3804 

ChoUilic  acid.  Choloidic  acid. 

C,,H,oOg      -      2H.,0     -     C,4H3803 

Cholalic  acid.  Dyslysin. 

Hoppe-Seyler  regards  choloidic  acid  as  merely  a  mixture  of  cholalic 
acid  and  dyslysin,  the  latter  being  a  neutral  resinous  body,  insoluble 
in  water  and  alcohol,  and  only  sparingly  soluble  in  ether. 

Tests  fm'  the  bile  acids.  (a)  Pettenkofer's  test. — Add  to  the  liquid 
a  few  drops  of  a  strong  solution  of  cane  sugar  and  a  few  drops  of  con- 
centrated sulphuric  acid,  and  keep  at  a  temperature  of  about  70°  C,  and 
a  cherry-red  or  dark  reddish-purple  colour  appears.  The  presence  of 
nitrates  and  chlorates  delays  the  reaction.  Albuminoids,  lecithin,  oleic 
acid,  cerebrin,  phenol,  turpentine,  benzin,  tannic  acid,  salicjdic  acid, 
morphia,  codeia,  amyl-alcohol,  cod-liver  oil,  and  camphor  give  a  similar 
reaction.  The  red  liquid  produced  by  the  reaction  is  dichroic,  and 
gives  two  absorption  bands  between  F  and  E.  When  examined  by 
the  spectroscope,  the  red  liquid  formed  by  the  action  of  strong  sul- 
phuric acid  on  albuminoids  is  not  dichroic,  and  those  Avith  oleic  acid  and 
amyl-alcohol  show  no  absorption  bands.  Still,  as  stated  by  Witthaus, 
the  spectroscopic  appearances  with,  different  fluids  are  not  sufficiently 
definite  to  serve  as  a  check  to  the  Pettenkofer  reaction. 

(/3)  Bogoinoloff's  test. — Evaporate  an  alcoholic  solution  to  dryness; 
spread  out  the  residue  on  a  white  plate,  and  wet  with  one  or  two  drops 
of  concentrated  sulphuric  acid  and  one  drop  of  alcohol.  Shades  of 
colour  will  be  shown  from  centre  to  circumference — yellow,  orange,  red, 
violet,  and  indigo. 

(y)  Strassburg's  test. — Dip  a  morsel  of  filter  pajDer  in  fluid,  then  into 
a  solution  of  cane  sugar,  allow  it  to  dry,  and  let  a  drop  of  concentrated 
sulphuric  acid  trickle  down  a  glass  rod  to  the  centre  of  the  paper; 
in  a  quarter  of  a  minute  the  sjDOt  Avill  become  translucent  and  transmit 
light  of  a  violet  colom\ 

Physiological  characters  of  the  bile  acids. — From  their  constitution, 
one  would  infer  that  the  bile  acids  are  formed  in  the  liver  by  the  union 
of  cholalic  acid  and  taurin  or  glycocin.  Glycocin  and  taurin,  as 
already  explained,  may  originate  from  the  decomposition  of  albuminoids, 
and  it  is  probable  that  cholalic  acid  has  the  same  origin.  This  view 
receives  some  support  from  the  similar  behaviour  of  albuminoids,  the  bile 
acids,  and  cholalic  acids  towards  sugar  and  concentrated  sulphuric  acid. 
Some  have,  on  the  contrary,  suj^posed  that  the  non-nitrogenous  cholalic 
acid  may  be  derived  from  fats.    After  their  formation,  the  acids  pass  into 


THE  NITROQENO  US  A  CTDS.  1 09 

the  intestine,  and  there  they  are  partially  decomposed  into  cholalic 
acid,  choloidic  acid,  dyslysin,  glycocin,  and  taurin,  and  some  of  these 
products  are  reabsorbed  into  the  blood.  The  remainder  is  voided  in 
the  faeces.  In  the  blood,  or  in  the  tissues,  the  bile  acids  and  their 
derivatives  are  no  doubt  decomposed  still  further.  At  all  events,  Avhen 
injected  into  the  blood — in  cases  of  biliary  fistulse  in  rabbits,  by  which 
it  was  possible  to  collect  the  bile — it  was  found  that  only  a  third  or  a 
fourth  part  of  the  acid  injected  appeared  in  the  bile,  the  remainder 
disappearing.  Injections  of  the  bile  acids  into  the  blood  cause  de- 
struction of  red  blood  corpuscles,  slowing  of  the  pulse  and  of  the 
respiratory  movements,  fall  of  arterial  pressure,  and  lowering  of 
the  bodily  temperature.  Doses  of  from  2  to  4  grammes  given  to  a 
dog,  caused  epileptiform  convulsions,  the  passing  of  very  dark- 
coloured  urine,  and  death.  The  biliary  acids  may  be  detected  in  the 
blood  and  urine  in  jaundice  and  acute  atrophy  of  the  liver.  Several 
important  physiological  questions  relating  to  the  action  of  the  bile 
acids  will  be  discussed  in  treating  of  the  bile. 

Chap.  VIII. —NITROGENOUS  BODIES  CONTAINING  NO  OXYGEN. 

1.  Trimetliijlamine,  (CH3)3N",  occurs  normally  in  human  urine,  and  it 
has  been  found  in  the  blood  of  the  calf,  in  cod-liver  oil,  ergot,  cheno- 
podium,  yeast,  guano,  herring-brine,  and  in  many  flowers.  It  is  an 
oily  fluid,  having  an  odour  of  fish,  boils  at  9°  C ,  is  soluble  in  water, 
alcohol,  and  ether,  and  has  an  alkaline  reaction.  It  is  also  found  among 
the  products  of  the  decomposition  of  albuminous  bodies. 

2.  Naphthylamine,  C-^^^^,  has  been  found  among  the  oxidation  pro- 
ducts of  albuminous  matter  (Schiitzenberger),  and  naphthalene  (C^^oHg) 
in  minute  quantity  has  been  detected  in  the  urine.     (Hoppe-Seyler.) 

3.  Lidol,  CgH^N,  belongs  to  the  group  of  aromatic  bodies  related  to 
indigo ;  indeed,  it  may  be  regarded  as  the  nucleus  of  the  indigo  group. 
Thus  various  plants  yield  indigo,  or  indigo-blue,  indigotin,  CgHgNO. 
This,  by  the  action  of  reducing  agents,  becomes  indigo-white,  or  indi- 
gogen,  CgHgNO.  Again,  a  third  body,  isatin,  CgIl5N02,  is  produced  by 
the  action  of  nitric  or  chromic  acid  on  indigo, — CgHgNO  -f  0  =  Cj^HgNOg. 
The  parent  of  these  three  bodies  is  indican,  CggHg^NO^^^,  which  is  a 
colourless  substance  existing  in  the  plants  that  yield  indigo.  Inclican, 
when  boiled  Avith  acids,  splits  up  into  indigo-blue  and  a  substance 
named  indiglucin,  CgHjoOg.     Thus — - 

C06H31NO17     +     2H„0     =     CgHgNO     +     SlCgHioOg). 

Indican.  Indigo-blue.  Indiglucin. 

Now,  isatin,   CgHpNOa,  plus  a  molecule  of  water,   HoO,  yields  isatic 


110  THE  CHEMISTRY  OF  THE  BODY. 

acid,  CgH-NO.j,  wliich  is  a  hydroxyl  derivative  of  iiidol,  or  trioxindol. 
Thus,  trioxindol  may  be  expressed  CjjH^N(H0)3.  Trioxindol  by  re- 
duction yields  dioxindol  CgH^N(HO)o,  and  oxindol  CsHgN(HO). 
Finally,  Baeyer  and  Emmerling  represent  all  these  bodies  by  the  fol- 
lowing formulne,  in  which  the  benzin  nucleus,  i^^i,  pla}'s  an  important 
part — 

/   COH  /C— OH  /C— OH  /  C— O 


CbH4\        C  CeH4<        C— OH    CcHjx        C-OH    CgHj  /         C-0 


\NH  \NH  \N— OH 

Oxindol.  Dioxiudol.  Trioxindol. 


C6H4< 


/'CH 


\NH 


\  I 


Thus  indol  may  be  obtained  from  indigo  by  converting  the  indigo  into 
isatin,  dioxindol,  and  oxindol,  and  then  reducing  the  oxindol  by  zinc 
dust.  The  relationship  of  these  bodies  may  also  be  illustrated  by 
putting  their  formulae  in  series,  thus — 


Indol,     - 

-        -    CgH^N. 

Isatin,   - 

-     CgHsNO, 

Oxindol, 

-     CgH^NO. 

Indigo-white, 

-    CgH^NO 

Dioxindol, 

-         CgHyNOo. 

Indigo-blue,  - 

-    CsHgNO. 

Isatyde, 

-        -    CsHeNOo. 

We  pass  from  indol  to  indigo-blue  by  successive  oxidations,  and  from 
indigo-blue  to  indol  by  successive  reductions.  It  is  of  more  importance, 
however,  to  observe  that  indol  is  also  obtained  by  the  decomposition  of 
albumin  through  the  agency  of  a  ferment  in  the  pancreatic  juice. 
(Nencki  and  Kiihne.)  It  appears  as  an  oily  fluid,  which,  when  mixed 
with  water,  solidifies  to  a  crystalline  mass,  and  on  recrystallization  from 
pm-e  water,  crystals  of  pure  indol  are  obtained,  which  melt  at  52°  C. 
Indol  has  a  peculiar  fsecal  odour,  like  that  of  naphthylamine ;  it  is 
readily  soluble  in  alcohol  and  ether,  and  it  acts  as  a  very  weak  base. 
One  of  its  characteristic  properties  is  to  give  a  reddish  precipitate  with 
dilute  fuming  nitric  acid  :  this  is  soluble  in  alcohol,  "and  the  alcoholic 
solution  mixed  with  hydrochloric  acid  colours  fir  wood  cherry-red, 
changing  after  a  while  to  dirty  brown-red."  (Baeyer.)  The  history  of 
indol,  as  a  decomposition-jDroduct  of  albuminoids,  prepares  us  for  finding 
it  in  the  intestines  and  in  the  faeces,  as  is  the  case,  and  it  also  exists  in 
all  putrefying  albuminoids.  Part  of  it  thus  formed  in  the  intestine  is 
evacuated  and  a  portion  may  be  changed  into  indican  which  is  absorbed 
and  finally  excreted  in  the  lurine  by  the  kidneys. 


NITROGENOUS  BODIES  CONTAINING  NO  OXYGEN.      \\\ 

4.  Skatol,  G^^,  or  methyl-indol,  C3Hg(CHg)X,  may  be  represented 
l)y  the  formula — 

^--N=  CH 

C6H4<f  I 

It  is  found  in  human  excrement  along  \\i\h  indol  and  phenol,  and  it  is 
also  one  of  the  products  of  the  pancreatic  digestion  of  albuminoids.  The 
fseces  of  dogs  contain  no  skatol,  but  only  indol  and  an  offensive  volatile 
yellow  oil,  the  nature  of  which  is  not  known.  It  is  said  that  a  similar 
oil  is  met  with  in  various  fluids  of  the  human  body  in  pathological  con- 
ditions. In  small  doses,  skatol  has  no  evident  physiological  action,  but 
in  large  doses  it  produces  disturbance  of  the  nervous  system  and  even 
tetanus.  It  appears  in  irregularly  dentate  shining  plates,  having  a 
faecal  odour  and  melting  at  94°  C.  Fuming  nitric  acid  gives  a  white 
cloudy  precipitate  "with  its  solutions,  thus  distinguishing  it  from  indol. 

,  5.  Pyrrol,  C^Hgls',  a  substance  produced  when  animal  or  vegetable 
matters  containing  nitrogen  are  subjected  to  destructive  distillation, 
has  been  found  in  the  faeces  and  in  the  urine,  and  probably  arises  in 
these  circumstances  from  the  decomposition  of  albuminous  matter. 

Chap.  IX.— THE  PIGMENTS. 

Various  pigments  occur  in  the  body,  as  in  the  blood,  the  bile,  the 
urine,  the  skin,  the  choroid  coat  of  the  eye,  and  in  muscular  tissue. 
The  parent  of  most  of  these  is  in  all  probability  the  pigment  of  the 
blood,  haemoglobin.  One  of  the  characteristic  properties  of  pigments 
is  that  when  white  light  is  passed  through  a  solution  containing  the 
pigment  and  then  through  a  prism,  part  of  the  light  "will  be  absorbed, 
so  that  certain  bands  appear  in  the  spectrum,  termed  absorption  bands, 
or  a  portion  of  the  spectrum  may  be  entirely  absorbed.  The  detection 
of  these  bands,  the  position  of  which  in  the  spectrum  is  constant  for 
each  substance,  has  made  the  spectroscope  a  useful  instrument  for 
physiological  research,  and  the  study  of  the  position  of  the  bands, 
and  of  the  way  in  which  the  spectrum  of  each  substance  may  be  modi- 
fied by  subjecting  the  substance  to  various  chemical  operations  has 
added  largely  to  our  knowledge  of  the  nature  and  relations  of  these 
pigments.  It  is  therefore  necessary  at  this  stage  briefly  to  describe 
the  spectroscopic  method  of  research  so  as  to  make  intelligible  the 
results  obtained  in  this  field  of  inquiry. 

When  white  light  is  passed,  through  a  prism  composed  of  crown  or  flint  glass,  or 
of  a  triangular  bottle  with  glass  sides  containing  the  highly  refractive  substance, 
bisulphide  of  carbon,  a  continuous  spectrum  is  obtained,  showing  the  foUowuig 


112 


THE  CHEMISTRY  OF  THE  BODY 


series  of  colours — red,  orange,  yellow,  green,  blue,  indigo,  violet;  and  if  the  light 
be  that  of  the  sun,  the  well  known  Hues  of  Fraunhofer,  with  suitalde  arrangements, 
also  become  visible.  The  first  Fraunhofer  line  A  is  in  the  red,  and  a  little  to  the 
right  and  also  in  the  red  are  is  and  c ;  D  is  in  the  orange-yellow  ;  e  in  the  green  ; 
F  between  blue-green  and  blue ;  G  in  the  violet-blue  ;  and  ii  in  the  violet.  The 
bright  yellow  line  seen  when  the  vapour  of  sodium  is  in  the  flame  corresponds  with 
the  line  d,  and  this  line  D  is  called  sometimes  the  sodium  line.  The  position  of 
these  fixed  lines  corresponds  to  a  certain  wave-length  (X)  of  light,  and  the  wave- 
length is  usual) J'  expressed  in   lO-millionths  of  a  millimetre.     Thus,  the  wave- 

V  Gr 


BC 


D 


E 


7  5'70l     6,5  60  i 


5,0 


4.& 


■10 


I     I  I  I  I  I 

Fig.  41. — Scale  of  wave-lengths. 

lengths  of  some  of  the  chief  tixed  lines  shown  in  the  accompanying  scale  (Fig.  41) 
as  determined  by  Angstrom^  are  :— b,  6874;  c,  65G7 ;  D,  5894;  E,  5273  ;  F,  4865;  and 


Fig.  42.— Arrangement  of  .spectroscope,  a,  Collimator,  with  adjustable  slit 
at  left  end  of  tube  and  collimating  lens  at  right  end  ;  b,  telescope,  moving 
on  graduated  arc  divided  into  degrees  ;  c,  prism  or  combination  of  prisms  ; 
D,tube  for  scale  ;  e,  mirror  for  illuminating  scale  ;  f,  specially  constructed 
vessel  with  parallel  glass  sides  for  holding  fluid,  the  spectrum  of  which  is 
under  examination  ;  g,  lens  for  condensing  light  of  Argand  flame  h. 
I,  vessel  for  deep  layer  of  fluid.  (From  a  photograph  taken  for  this  work 
by  Dr.  MacJIunn.) 

G,  4310.      In  this  scale,  provided  along  with  the  micro-spectroscope  of  Zeiss  of 
Jena,  on  the  suggestion  of  Professor  Abbe,  the  figures  indicate  wave-lengths  in 

1  The  wave-lengths  given  by  Angstrom  in  Becherches  sur  h  Spectre  Solaire,  Spectre 
Normal  du  Soldi,  p.  25,  Upsala,  1868,  are  as  follows  :  a,  7604  ;  b,  6867  ;  c,  6562  ; 
D,  5892  ;  E,  5209  ;  f,  4860  ;  G,  4307.  These  are  more  correct  than  those  given  in 
the  text.  For  physiological  purposes  it  is  only  necessary  to  measure  bands  in 
millionths  of  a  mm. 


THE  PIGMENTS. 


113 


lOOjOOOths  of  a  mm.,  and  each  division  indicates  a  difference  in  wave-length  equal 
to  100,000th  of  a  mm.  =  "00001  mm.  Thus  take  e  :  X  is  seen  to  be  =  about  52'7 
one  hundred-thousandths  of  mm.,  that  is  527  millionths,  or  with  careful  measure- 
ment 5273  ten  millionths  of  mm. 

The  spectroscopes  employed  in  physiological  work  (see  Fig.  41)  may  be  either 
such  as  are  used  by  physicists,  consisting  of  a  prism,  c,  of  flint-glass,  or  combina- 
tion of  prisms  mounted  on  the  centre  of  a  table,  a  tube  a,  called  the  collimator, 
having  an  adjustable  slit  at  one  end,  and  a  lens,  the  coUimafing  lens,  at  the  other  ; 
a  telescope,  b,  for  examining  the  spectrum,  and  a  tube,  d,  by  which  an  image  of  a 
scale  photographed  on  glass,  placed  at  E,  is  reflected  from  the  prism  into  the  eye 
of  the  observer  looking  through  the  telescope  b. 
In  usiug  the  instrument,  a  black  velvet  cloth 
is  thrown  over  the  prism  and  ends  of  the 
tubes,  the  light  h  is  adjusted  so  as  to  illumi- 
nate the  slit,  the  width  of  the  slit  is  also 
carefully  adjusted,  and  by  careful  focvising  of 
the  telescope,  B,  a  well-defined  spectrum  will 
then  be  seen,  having  an  illuminated  image  of  the 
scale  above  or  below  it.  If  now  a  solution  of  per- 
manganate of  potash,  in  a  vessel  having  flat 
glass  sides,  be  placed  in  front  of  the  slit,  it  will  be 
found  that  the  red  and  blue-violet  parts  of  the 
spectrum  are  unaltered,  but  there  are  dark  bands 
in  the  yellow  and  green,  that  is,  the  red  and 
violet  parts  of  the  spectrum  are  transmitted,  but 
portions  of  the  rays  producing  yellow  and  green 
have  been  absorbed.  Again,  if  a  solution  of  chloro- 
phyll is  substituted  for  the  permanganate,  an- 
other kind  of  absorption  spectrum  is  seen :  "in 
the  middle  of  the  red  a  black  band  between  b 
and  c,  three  feeble  absorption  strise  in  orange, 
yellow,  and  green,  while  the  violet  and  indigo 
colours  are  entirely  shaded."      (MacMunn,    7'Ae 

Spectroscope  in  Medicine,  p.  6.)     Such  bands  are  ^'°;  43.— Hsematoscope.    r,  A  glass 

■^  ■"  ,  '  r        /  plate;  c,  piston-hke  tube  having  at  its 

termed  absorption  bands.     To  see  the  bands  dis-  inner  end  a  glass  plate.  By  sliding  c  in 

tinctly  it  is  usually  necessary  to  dilute  the  fluid  ^B^f  is  vS?and  fh^ tLTcknlsTol 

and  to  examine  it  in  a  trough  having  parallel  *e  stratum  of  fluid  is  read  off  on  a 

.  .  1  millimetre  scale  on  the  tube  c.     E, 

glass  sides,  or  such  an  mstrument  as  the  Hcema-   vessel  for  holding  fluid  to  be  ex- 

toscope  of  Hermann,  seen  in.  Fig.  43,  may  be  em-  fj^^ld  Vi  screw""  ^^^'^^  ^P^^'^''*''^ 
ployed. 

The  spectroscope  has  also  been  adapted  to  the  microscope.  In  the  micro-spectro- 
scope there  is  a  compound  prism  consisting  of  two  prisms  of  flint  glass  between 
three  prisms  of  crown  glass,  united  by  means  of  Canada  balsam.  Thus,  as  seen  in 
Fig.  44,  there  is  sufficient  dispersion,  while  the  light  continiies  in  the  same  path. 

Below  the  prisms  there  is  a  slit,  the  width  of  which  may  be  regulated  by  a  side 
screw,  and  the  tube  bearing  the  prisms  may,  by  a  rack  and  pinion  movement,  be 
brought  near  the  slit  or  removed  from  it.  Usually  the  micro-spectroscope  is 
furnished  with  a  side  tube  which  admits  the  light  to  a  small  right-angled  prism, 
which  reflects  it  upwards  into  the  eye  of  the  observer  through  that  portion  of  the 
slit  which  this  right-angled  prism  covers.  By  this  arrangement,  on  placing  a  small 
I.  H 


114 


THE  CHEMISTRY  OF  THE  BODY 


glass  tube  containing  the  solution  outside  the  hole  in  the  end  of  the  side  tube,  a 
second  spectrum  is  seen  which  may  be  compared  with  the  one  obtained  from 
the  object  under  examination.     Two  such  micro-spectroscopes  are  shown  in  Figs. 


Crownglas                  Crownglas                 Crownglas 

L||,                 -/\                   /-^ 

W^. ^/.^.^--^ -—---.^.^..^^^^ 

3B^^^H 

^^^^^/            X/             A:jm^^^m 

Flintglas                      Flintglas 

Fio.  44. — Arrangement  of  pi-isms  in  direct  vision  spectroscope.    (Gscheidlen.) 


45  and  46.  In  using  the  micro-spectroscope,  a  tube  containing  the  fluid  is  placed 
horizontally  on  the  stage  of  the  microscope,  and  the  light  is  transmitted  through 
it  from  the  mirror  below  the  stage.  The  spectroscope  is  substituted  for  the  eye- 
piece of  the  microscope. 


Fig.  45. — Micro-spectroscope.  A,  slit,  adjust- 
able by  screw  C  ;  B,  field  glass  ;  D,  three 
prisms  ;  E,  movement  for  bringing  prisms 
nearer  to  or  farther  away  from  the  slit  A ;  the 
outlines  of  a  plate  bearing  the  slit  seen  in 
dotted  lines,  F,  G,  are  arrangements  for  in- 
creasing or  diminishing  breadth  of  slit. 
These  arrangements  are  seen  in  Fig.  46. 


THE  PIGMENTS, 


115 


Pig  46. — Micro-spectroscope  of  Sorby. 
A,  tube  carrying  prisms  ;  B,  five  prisms — 
three  of  crown  and  two  of  flint  glass  ;  C, 
prism  for  obtaining  a  second  spectrum  by 
light  entering  at  sUt  K  reflected  from  mir- 
ror I  through  tube  containing  fluid  held  by 
spring  cUps  ;  H,  screw  and  rod  for  regul- 
ating sUt  E  ;  L,  lens  ;  M,  tube  for  body 
of  microscope.  At  upper  end  on  left  hand 
is  the  apparatus  for  obtaining  an  image 
of  scale  placed  at  P,  movable  by  screws 
G  and  0,  by  light  reflected  from  mirror 
Q  passing  along  tube  V. 


Fig  47. — View  of  plate  K  belonging  to 
the  micro-spectroscope  seen  in  Fig.  45, 
and  having  slit  narrowed  by  the  plates  a 
and  b,  moved  by  screw  H,  and  shortened 
in  length  by  plates  e  e,  moved  by  screw  d. 


116  THE  C HEM  1ST R Y  OF  THE  BODY. 

In  1862,  Hoppc-Scyler  noticed  the  remarkable  spectrum  produced  by 
the  absorption  of  light  by  a  very  dilute  solution  of  blood.  Immediately 
thereafter,  the  subject  was  investigated  by  Professor  Stokes  of 
Cambridge  and  communicated  to  the  Royal  Society  in  1864.^  If  white 
light  be  transmitted  through  a  thin  stratum  of  blood,  two  distinct 
absorption  bands  ^vill  be  seen.  One  of  these  bands  next  D  is  narrower 
than  the  other,  has  more  sharply  defined  edges,  and  is  undoubtedly 
blacker. 

"Its  centre,"  as  described  by  Professor  Gamgee  [op.  cit.  p. 97),  "corresponds  with 
wave-length  579,-  and  it  may  conveniently  be  distinguished  as  the  absorption  band  a 
in  the  spectrum  of  oxy-hremoglobin.  The  second  of  the  absorption  bands,  i.  e.  the  one 
next  to  E,  which  we  shall  designate  ^,  is  broader,  has  less  sharply  defined  edges, 
and  is  not  so  dark  as  a.  Its  centre  corresponds  approximately  to  W.  L.  553 "8.  On 
diluting  very  largely  with  water,  nearly  the  whole  of  the  spectrum  appears  beauti- 
fully clear  except  where  the  two  absorption  bands  are  situated.  If  dilution  be 
pursued  far  enough  even  these  disappear  ;  before  they  disappear  they  look  like 
faint  shadows  obscuring  the  limited  part  of  the  spectrum  which  they  occupy.  The 
last  to  disappear  is  the  band  a.  The  two  absorption  bands  are  seen  most  distinctly 
when  a  stratum  1  cm.  thick  of  a  solution  containing  1  part  of  hemoglobin  in  1000 
is  examined  :  they  are  still  perceptible  when  the  solution  contains  only  1  part  of 
haemoglobin  in  10,000  of  water." 

Suppose,  on  the  other  hand,  Ave  begin  -with  a  solution  of  blood  in  ten 
times  its  volume  of  water,  we  then  find  that  such  a  solution  cuts  off  the 
more  refrangible  part  of  the  spectrum,  leaving  nothing  except  the  red, 
"or  rather  those  rays  having  a  wave-length  greater  than  about  600 
millionths  of  a  millimetre."  On  diluting  further,  the  effects,  so  Avell 
described  by  Professor  Gamgee,  are  as  follows — 

"  If  now  the  blood  solution  be  rendered  much  more  dilute  so  as  to  contain  8  per 
cent,  of  haemoglobin,  on  examining  a  stratum  1  centimetre  wide,  the  spectrum 
becomes  distinct  up  to  Fraunhofer's  line  D  (W.  L.  589),  i.e.  the  red,  orange,  and 
yellow  are  seen,  and,  in  addition,  also  a  portion  of  the  green  between  b  and  F. 
Immediately  beyond  D,  and  between  it  and  b,  however  (between  W.  L.  595  and 
518),  the  absorption  is  intense." 

These  facts  were  observed  by  Hoppe-Seyler.  Professor  Stokes  made 
the  very  important  contribution  of  observing  that  the  spectrum  was 
altered  by  the  action  of  reducing  agents.  Hoppe-Seyler  had  remarked 
that  the  colouring  matter,  so  far  as  the  spectrum  was  concerned,  was 
unaffected  by  alkaline  carbonates  and  caustic  ammonia,  but  was  almost 
immediately  decomposed  by  acids,  and  also  slowly  by  caustic  fixed 
alkalies,    the  coloured  product  of  decomposition  being  haematin,   the 

1  Proc.  of  Royal  Society,  vol.  xiii.;  also  Philosophical  Magazine,  1864. 
"  Dr.  Gamgee  gives  the  measurements  of  the  wave-lengths  in  millionths,  not  in 
ten- millionths  of  a  mm. 


THE  PIGMENTS.  117 

spectrum  of  which  was  known.  Professor  Stokes  was  led  to  investigate 
the  subject  from  its  physiological  interest,  as  may  be  observed  on 
quoting  his  own  words —  ^ 

"  But  it  seemed  to  me  to  be  a  point  of  special  interest  to  inquire  whether  we  could 
imitate  the  change  of  colour  of  arterial  into  that  of  venous  blood,  on  the  sup- 
position that  it  arises  from  reduction." 

He  found  that — 

"If,  to  a  solution  of  proto-sulphate  of  iron,  enough  tartaric  acid  be  added 
to  prevent  precipitation  by  alkalies,  and  a  small  quantity  of  the  solution, 
previously  rendered  alkaline  by  either  ammonia  or  carbonate  of  soda,  be 
added  to  a  solution  of  blood,  the  colour  is  almost  instantly  changed  to  a 
much  more  purple-red,  as  seen  in  small  thicknesses,  and  a  much  darker 
red  than  before,  as  seen  in  greater  thickness.  The  change  of  colour  which 
recalls  the  difference  between  arterial  and  venous  blood  is  striking  enough, 
but  the  change  in  the  absorption  spectrum  is  far  more  decisive.  The  two 
highly  characteristic  dark  bands  seen  before  are  now  replaced  by  a  single 
band,  somewhat  broader  and  less  sharply  defined  at  its  edges  than  either  of  the 
former,  and  occupying  nearly  the  position  of  the  bright  band  separating  the  dark 
bands  of  the  original  solution.  The  fluid  is  more  transparent  for  the  blue  and  less 
so  for  the  green  than  it  was  before.  If  the  thickness  be  increased  till  the  whole 
of  the  spectrum  more  refrangible  than  the  red  be  on  the  point  of  disappearing, 
the  last  part  to  remain  is  green,  a  little  beyond  the  fixed  line  6,  in  the  case  of  the 
original  solution,  and  hlue  someway  beyond  F,  in  the  case  of  the  modified  fluid." 

From  these  observations,  Professor  Stokes  was  led  to  the  important 
conclusion  that — 

"The  colouring  matter  of  blood,  like  indigo,  is  capable  of  existing  in  two 
states  of  oxidation,  distinguishable  by  a  difference  of  colour,  and  a  fundamental 
difference  in  the  action  on  the  spectrum.  It  may  be  made  to  pass  from  the  more 
to  the  less  oxidized  state  by  the  action  of  suitable  reducing  agents,  and  recovers 
its  oxygen  by  absorption  from  the  air." 

To  the  colouring  matter  of  the  blood.  Professor  Stokes  gave  the 
name  of  criiorine,  and  described  it  in  its  two  states  of  oxidation  as 
scarlet  cruorine  and  purple  cniorine.  The  name  hcemoglobin,  given  to  it 
by  Hoppe-Seyler,  is  generally  employed.  When  united  with  oxygen  it 
is  called  oxy-hsemoglobin,  and  when  in  the  reduced  state  it  is  termed 
reduced  haemoglobin,  or  simply  haemoglobin. 

We  are  now  in  a  position  to  discuss  the  properties  of  the  various 
pigments,  including  their  optical  properties,  which  are  of  much  physio- 
logical interest.  The  latter  are  well  illustrated  by  Plate  I.,  which  is  a 
chart  of  physiological  spectra,  specially  prepared  for  this  work  by 
Dr.  Charles  A.  MacMunn,  of  Wolverhampton,  who  has  for  many  years 
made  the  application  of  the  spectroscope  to  physiology  and  to  practical 
medicine  a  special  subject  of  study. 


118 


TtlE  CHEMISTRY  OF  THE  BODY. 


A. — The  Pigment  of  the  Blood  and  its  Derivatives. 

1.  HamogJobin,  Juvmafoglohulin,  criwrin,  ha'inatocri/sfaUin,  conveniently 
represented  by  the  symbol  H,  is  probably  the  most  complex  substance 
known.  Its  percentage  composition  varies  slightly  in  different  animals, 
as  shown  in  the  follo^^dns;  table — ^ 


Animal, 

Dog. 

Dog. 

Guinea- 
Pig. 

Squirrel. 

Goose. 

Horse. 

Carbon, 

54-15 

53-85 

54-12 

54-09 

54-26 

54-87 

Hydrogen, 

7-18 

7-32 

7-36 

7 -.39 

7-10 

6-97 

Nitrogen,  - 

16-33 

16-17 

16-78 

16-09 

16-21 

17-31 

Oxygen,     - 

21-24 

21-84 

20-68 

21-44 

20-69 

19-73 

Sulphur,    - 

0-67 

0-39 

0-58 

0-40 

0-54 

0-65 

Iron,    .       -       -       - 

0-43 

0-43 

0-48 

0-59 

0-43 

0-47 

Phosphoric  aciJ,     - 

0-77 

Author, 

C.  Schmidt. 

Hoppe 

Seyler. 

Kossel. 

Preyer,  on  the  assumption  that  the  molecule  contains  one  atom  of 
iron,  has  suggested  the  empirical  formula,  C6ooH9enNig4FeS30;^79,  but  no 
rational  formula  has  been  offered,  and  its  molecular  structure  is  un- 
known. It  is  the  only  proximate  principle  containing  iron — about  -4 
per  cent. 

In  Professor  Arthur  Gamgee's  well-known  work  on  the  Physiological 
Chemistry  of  the  Animal  Body  (already  quoted),  pp.  85,  86,  87,  88,  no 
fcAver  than  eight  methods  of  obtaining  haemoglobin  are  described,  and 
I  take  the  liberty  of  reproducing  only  two  of  these,  Numbers  IV.  and 
VII.,  both  of  which,  in  my  O'wn  experience,  have  yielded  excellent 
results — 

' '  IV.  The  defibrinated  blood  of  the  dog  is  mixed  with  its  own  volume  of  dis- 
tilled water,  and  the  diluted  fluid  is  treated  with  one  fourth  of  its  volume  of 
alcohol.  The  mixture  is  kept  for  twenty-four  hours  at  a  temperature  of  0°  C,  or 
below.  The  crystals  which  separate  are  dissolved  in  as  small  a  quantity  as 
possible  of  water  at  25°  to  30°  C. ,  and,  the  solution  being  cooled  to  0°  C. ,  a  fourth 
of  its  volume  of  alcohol  is  added.  It  is  better  to  place  the  fluid  in  a  freezing 
mixture  at  a  temperature  of  -  10°  to  -  20°  C.  for  twenty-four  hours.  The  whole 
fluid  then  becomes  filled  with  a  magma  of  crystals.  The  process  of  recrystallization 
may  be  several  times  repeated." 

"  VII.  500  c.c.  of  defibrinated  dog's  blood  are  treated  with  31  c.c.  of  ether,  and  the 
mixture  shaken  for  some  minutes.  It  is  then  set  aside  in  a  cool  place.  After  a 
period  varying  from  twenty -four  hours  to  three  days  the  liquid  has  become  con- 
verted into  a  thick  magma  of  crystals.     These  may  be  separated  by  placing  in 

^  EoUet,  Physiologie  des  Blutes  ;  Hermann's  Handbuch  der  Physiologie,  vol.  iv. 


TEE  PIGMENTS. 


119 


tubes  and  using  the  centrifugal  apparatus.  The  cakes  of  crystals  thus  obtained 
are  mixed  with  water  holding  one  fourth  of  its  volume  of  alcohol  in  solution,  and 
again  centrifugalized.  By  repeating  this  process  the  crystals  are  obtained  free 
from  serum  albumin.  If  requisite,  the  crystals  are  dissolved  in  water,  and  re- 
crystallized  by  the  method  mentioned  under  IV." 

To  obtain  hsemoglobin  crystals  suitable  for  microscopical  examination, 
the  method  of  Gscheidlen,  thus  described  by  Dr.  Gamgee,  may  be 
successfully  adopted.  "  In  order  to  obtain  very  large  crystals  of  oxy- 
hsemoglobin  for  microscopic  examination,  Gscheidlen  seals  defibrinated 
dog's  blood  which  has  stood  in  the  air  for  twenty-four  hours,  in  narrow 
glass  tubes  (vaccine-tubes  answer  well),  and  keeps  the  tubes  for  some 
days  at  a  temperature  of  37°  C.  On  opening  these  tubes  and  emptying 
their  contents  into  a  watch-glass,  and  allowing  some  time  for  evapor- 
ation to  take  place,  there  are  formed  crystals  of  extraordinary  size." 
(Gamgee,  op.  cit.  p.  88.) 

Hsemoglobin  exists  in  two  conditions — (1)  that  of  oxy-haemoglobin, 
or  haemoglobin  united  with  oxygen,  HO;  (2)  reduced  hagmoglobin,  that 
is,  oxy-haemoglobin  from  which  the  oxygen  has  been  removed,  H.  To 
form  oxy-hsemoglobin,  1  gramme  of  dried  haemoglobin  absorbs  1  c.c.  of 


Fig.  48. — Crystals  of  oxy-hsemoglobin.  o,  b,  c,  and  c  (middle)  show  forms  from 
human  blood  and  that  of  the  majority  of  mammals  ;  d,  tetrahedral  crystals  from 
blood  of  guinea-pig  ;  /,  hexagonal  from  squirrel's  blood. 

oxygen,  and  this  oxygen  may  be  expelled  by  the  vacuum,  heat,  or 
reducing  agents.     HO  from  the  blood  of  man  and  the  majority  of 


120 


THE  CHEMISTRY  OF  THE  BODY. 


auimals  crystallizes  in  rhombic  prisms  of  a  blood-red  colour ;  that  of  the 
guinea-pig  crystallizes  in  tetrahedra,  and  that  of  the  squirrel  in  six- 
sided  plates  belonging  to  the  hexagonal  system  (Fig.  48,  a,  h,  c,  d,  f). 
It  does  not  crystallize  so  readily  from  the  blood  of  some  animals  as 
from  others.  Preyer  thus  classifies  these  varieties  according  to  facility 
of  crystallization  :  (1)  Very  difficult — calf,  pig,  pigeon,  frog ;  (2)  Difficult 
— man,  ape,  rabbit,  sheep ;  (3)  Easy — cat,  dog,  mouse,  horse ;  (4)  Very 
easy — rat,  guinea-pig. 

The  crystals  are  readily  soluble  in  water,  and  the  solubility  is  in  the 
inverse  ratio  of  their  facility  of  crystallization.  Carbonates,  phosphates, 
and  borates  of  the  alkalies,  the  alkalies  themselves,  serum,  urine,  solu- 
tions of  urea,  solutions  of  the  bile  acids,  and  glycerine  dissolve  oxy- 
haemoglobin.  Solutions  of  HO  give  a  precipitate  "with  potassium  carbo- 
nate, but  there  is  no  precipitate  %vith  acetate  of  lead  or  with  acetate  of 
lead  and  ammonia,  nor  "with  nitrate  of  silver,  although  the  last  three 
reagents  cause  decomposition  of  the  haemoglobin.  It  is  precipitated  by 
alcohol.  Solutions  of  haemoglobin  become  muddy  at  a  temperature 
of  bet"ween  70°  and  80°  C,  and  the  substance  is  decomposed  by  all  agents 
that  decompose  albuminoid  matters,  being  resolved  into  haematin,  and 
one  or  more  albuminoid  coagulable  matters  (to  which  the  name  globulin 
may  be  applied)  along  with  formic,  butyric,  and  other  volatile  fatty  acids. 

The  characteristic  spectrum  of  oxy-hsemoglobin  is  seen  in  Plate  I., 
sp.  2,  and  it  is  represented  somewhat  diagrammatically  in  Fig.  49,  B. 


Fig.  49. — Diagram  of  spectrum  of  hasmoglobin  A  ;  and  of  oxy-hsemoglobin  B. 

I  am  indebted  to  Dr.  MacMunn  for  measurements  of  the  wave-lengths 
by  which  the  position  of  the  absorption  bands  can  be  accurately 
defined.  As  to  the  method  of  making  the  measurements,  Dr.  Mac- 
Munn "writes  as  follows — 

"The  "wave-lengths  were  calculated  by  interpolation  curves  adapted  to  the 
scales  of  two  spectroscopes,  the  measurements  were  taken  on  the  photographed 
scale  of  each  spectroscope  independently  of  each  other,  and  then  reduced  to  wave- 
lengths by  means  of  each  curve.  If  any  marked  discrepancy  arose,  the  readings 
were  repeated  until  this  was  corrected.  The  measurement  of  the  edges  of  feeble 
bands  must  more  or  less  depend  on  the  "personal  equation"  of  the  observer, 
and  may  differ  by  a  few  millionths  of  a  millimetre,  in  which  they  are  calculated, " 

Dr.  MacMunn,  in  his  work  on  The  Spectroscope  in  Medicine,  p.  32,  thus 


THE  PIGMENTS. 


121 


describes  the  method  of  determining  the  wave-lengths  \>j  interpolation 
curves — 

"  A  piece  of  paper  ruled  into  square  inches  and  tenths  has  a  scale  of  wave-lengths 
ruled  off  along  one  edge,  and  the  edge  at  right  angles  to  this  has  a  scale  corre- 
sponding to  the  scale  of  the  instrument  marked  on  it.  The  vah;e  of  the  Fraun- 
hofer  lines  on  the  scale  of  the  spectroscope  is  observed,  and  by  a  reference  to  the 
above  numbers,  their  value  in  wave-lengths,  they  are  then  marked  in  their  proper 
place  on  the  scale  with  +  +.  A  curve  is  then  drawn  through  these  marks 
as  uniformly  as  possible.  When  a  band  or  bright  line  has  to  be  mapped  out,  all 
that  is  necessary  is  to  take  its  reading  on  the  scale  ;  then,  knowing  between  what 
lines  it  is  placed,  we  find  its  position  on  the  curve,  opposite  which  its  wave-length 
is  printed  on  the  right  hand  edge." 

The  measurements  for  oxy-hsemogiobin  in  one  millionths  of  mm.  are 
as  follows — 

"In  a  concentrated  solution  the  red  rays  only  are  transmitted,  light  is  cut  off 
completely  at  the  red  end  at  X706,  a  shading  extends  to  X647  ;  light  is  again 
completely  absorbed  at  X591,  and  a  shading  extends  to  X610.  In  a  more  dilute 
solution  one  broad  band  embracing  the  two  oxy-heemoglobin  bands  becomes 
detached  from  about  X589  to  X520.  Still  more  diluted,  the  first  band  extends 
from  X589  to  X564:,  with  its  darkest  part  from  X585  to  X569,  and  the  second 
from  X555  to  X517,  with  its  darkest  part  from  X552  to  X526.  In  a  greater 
degree  of  dilution  the  first  band  reads  X587  to  X566,  the  darkest  part  being  from 
X583  to  X571,  and  the  second  from  X550'5  to  X523,  the  darkest  part  ranging 
fromX549toX529." 

The  character  of  the 
absorption  spectrum  of 
oxy-hsemoglobin,  with 
different  strengths  of 
solution  in  a  layer  one 
centimetre  in  thickness, 
as  measured  by  the 
hsematoscope,  is  illus- 
trated graphically  by 
Rollet  (op.  cit.)  in  Fig.  50. 
Here  the  line  o  x  has  on 
it  at  the  proper  distances 
the  chief  Fraunhofer 
lines,  whilst  the  figures 
along  the  right  hand 
border  are  percentages 
of  the  amount  of  oxy- 
haemoglobin  present. 
Thus,  Avith  -1  per  cent, 
the  two  bands  are  narrow  and  pale,  they  gradually  become  broader 
until  they  fuse  at  nearly  "7  per  cent.,  and  at  -9  per  cent,  no  light  passes 


0.5  fL 


aC  B 


Fig.  50. — Graphic  representation  of  the  amount  of 
absorption  of  light  by  solutions  of  oxy-hfemoglobin  of 
different  strengths.  The  shading  indicates  the  amount 
of  absorption  of  the  spectrum. 


122  THE  CHEMISTRY  OF  THE  BODY. 

except  in  the  red.  It  will  be  observed  also  that  from  a  little  OA-er  -^ 
per  cent,  to  the  top  there  is  a  gradually  increasing,  though  slight, 
absorption  of  the  low  red. 

Preyer  has  devised  a  spectro-colorometric  method  of  estimating  the 
amount  of  oxy-haemoglobin  by  preparing  a  standard  solution,  having  the- 
absorptive  power  indicated  in  the  diagram  as  on  the  level  of  the  lines 
PP.  This  is  the  point  at  which  the  green  is  extinguished  and  only  red 
rays  are  transmitted.  The  specimen  of  blood  is  diluted  with  water 
until  it  gives  a  similar  spectrum  (that  is,  to  find  the  exact  point  at 
which  the  absorption  of  the  green  takes  place),  and  then  the  percentage 
amount  is  estimated  by  the  formula — 


x  —  K 


(b  +  w) 


b      ' 

in  which  K-  the  percentage  of  the  standard  solution,  b  =  the  amount  of 
blood,  and  ic  =  the  amount  of  Avatcr,  and  x  =  the  percentage  required. 
Thus,  suppose  2  c.c.  of  blood  required  25  c.c.  of  water  to  give  an  absorp- 
tion spectrum  similar  to  that  of  the  standard  spectrum,  the  percentage 
of  which  is  -85  ;  then 

(2  +  25) 
X  "  -85^ — - — ^=  11-4  per  cent,  of  oxy-haemoglobin. 

By  various  methods  the  oxygen  may  be  removed  from  oxy-haemo- 
globin. The  following  are  reducing  fluids  :  (1)  Stokes'  Fluid.  Thus,  to 
a  solution  of  sulphate  of  iron  is  added  a  small  amount  of  citric  or  of 
tartaric  acid,  and  then  ammonia  until  the  reaction  is  alkaline.  Ammonia 
does  not  precipitate  ferrous  hydrate  in  the  presence  of  the  vegetable 
acid,  and  a  clear  light  green  solution  is  obtained,  which  becomes  darker 
by  the  absorption  of  oxygen  on  exposure  to  the  air ;  (2)  a  solution  of 
stannous  chloride,  with  a  little  tartaric  acid  and  ammonia  added  until 
neutralization ;  (3)  a  solution  of  ammonium  sulphide.  When  any  of 
these  fluids  is  added  to  a  solution  of  oxy -haemoglobin,  and  the  solution 
is  examined  by  the  spectroscope,  the  two  bands  of  oxy-haemoglobin 
disappear  and  in  their  stead  there  is  one  band,  seen  in  A,  Fig.  49  and 
in  Plate  I.  3.     The  spectrum  is  thus  described  by  Dr.  Gamgee — 

*'  The  spectrum  of  oxy-liEemoglobin  had  been  described  by  Hoppe-Seyler  when 
Professor  Stokes  made  the  remarkable  discovery  that  when  diluted  blood  is 
treated  with  certain  reducing  agents  the  colour  of  the  liquid  and  its  spectrum 
undergo  remarkable  changes  ;  the  former  loses  its  bright  red  and  acquires  a, 
brown  colour,  while  the  green  interspace  which  had  existed  betM^een  the  absorp- 
tion bands  a  and  /3  of  oxy-hsemoglobin  disappears,  and  instead  of  the  two 
bands  there  appears  a  single  one,  less  deeply  shaded,  and  with  less  finely  defined 
edges,  extending  between  D  and  E.  The  band  we  may  distinguish  as  absorption 
band  7." 


TEE  PIGMENTS. 


123 


Dr.  MacMunn  states  that  "the  broad  hazy  band  extends  from  A59T 
to  A536,  and  that  the  darkest  part  is  from  A573  to  A542." 

In  Fig.  51  there  is  represented  the  amount  of  absorption  mth  dif- 
ferent percentages  of  reduced  haemoglobin,  as  in  Fig.  50,  showing 
oxy-haemoglobin.  It  will  be  observed  that  the  absorption  band 
diminishes  in  breadth  as  the  solution  becomes  weaker,  the  blue  rays 
becoming  more  visible. 
With  very  weak  solutions, 
the  single  broad  band 
never  breaks  into  two 
narrow  ones,  but  gradu- 
ally fades  from  view. 
With  two  weak  solutions 
of  equal  strength,  that  of 
oxy-hsemoglobin  may  dis- 
tinctly show  the  two 
bands,  whilst  that  of  re- 
duced haemoglobin  shows 
no  band.  Further,  the 
general  appearance  of  the 
spectrum  of  reduced  hae- 
moglobin differs  from  that 
of  oxy-haemoglobin.  In 
the  former  less  of  the  blue 
end  is  absorbed,  and  even 
in  strong  solutions  some  of  the  bluish-green  rays  pass  through.  This 
accounts  for  the  difference  of  colour — the  blood  containing  oxy- 
haemoglobin  being  scarlet,  w^hilst  that  containing  reduced  haemoglobin 
is  purple.  The  first  kind  of  blood  allows  the  red  and  orange-yellow 
rays  to  pass,  and  the  second  kind  the  red  and  blue-green  rays.  The 
difference  is  thus  described  by  Professor  Michael  Foster — ^ 

"  In  dilute  solutions,  or  in  a  thin  layer,  the  reduced  hEemoglobin  lets  through 
so  much  of  the  green  rays  that  they  preponderate  over  the  red,  and  the  resulting 
impression  is  one  of  green.  In  the  unreduced  hfemoglobin  or  oxy-hsemoglobin, 
the  potent  yellow  which  is  blocked  out  in  the  reduced  hsemoglobin  makes  itself 
felt,  so  that  a  very  thin  layer  of  haemoglobin,  as  in  a  single  corpuscle  seen  under 
the  microscope,  appears  yellow  rather  than  red." 

Haemoglobin  is  widely  distributed  in  the  animal  kingdom.  Thus  it 
has  been  found  in  the  red  blood  corpuscles  of  all  vertebrates  except 
amphioxus  (in  which  it  is  found  in  the  plasma  only) ;  in  the  striated 

^  Handbook  Jor  Physiological  Laloratory,  by  Klein,  Burdon-Sanderson,  Foster, 
and  Lauder  Brunton. 


aCB       D  Eb 

Fig.  51. — Graphic  representation  of  the  amount  of 
absorption  of  light  by  solutions  of  reduced  haemoglobin 
of  different  strengths.  The  figures  on  the  right  border 
express  percentages. 


124  THE  CHEMISTRY  OF  THE  BODY. 

muscles  of  mammals  and  birds ;  in  the  cardiac  muscles  and  very  active 
muscles  of  other  vertebrates  ;  in  Ophiadis  lirens  (an  echinoderm.) ;  in  the 
blood  of  some  of  the  annelidse ;  in  the  fluid  in  the  perivisceral  cavity  of 
the  leech ;  in  the  larva  of  Chironoimis  (midge),  although  absent  in  other 
insects,  and  in  mj-riapods  and  arachnids  ;  in  the  l^lood  plasma  of  certain 
crustaceans ;  in  the  blood  of  certain  molluscs  (Planorhis) ;  in  the  mus- 
cular fibres  of  the  pharynx  of  certain  gastropods  {Lymnceus,  Paludina), 
and  in  the  ventral  ganglia  of  Aphrodite. 

Haemoglobin  forms  definite  compounds  Avith  at  least  other  two  gases — 
{a)  Carbonic-oxide  Hcemoglohin. — When  blood  is  shaken  up  with 
carbonic  oxide  it  assumes  a  red  arterial  colour,  and  if  examined 
spectroscopically  two  absorption  bands  are  seen  similar  to  those  of 
oxy-haemoglobin.  Careful  measurement,  however,  shows  that  both 
bands  are  slightly  nearer  the  violet  end  of  the  spectrum.  The  measure- 
ments given  by  Dr.  MacMunn,  calculated  from  Preyer's  Map  of  Spectra, 
are  :  "  First  band,  A583  to  A564 ;  second  band,  A547  to  A529;  or,  in  more 
concentrated  solutions,  A583  to  A561  and  A547  to  A521."^  This  com- 
pound, which  forms  crystals  like  those  of  oxy-haemoglobin,  is  remark- 
able for  its  stability ;  it  is  not  acted  on  by  those  agents  which  reduce 
oxy-hsemoglobin,  but  the  CO  may  be  driven  ofi"  by  passing  for  a 
long  time  a  stream  of  air  or  of  a  neutral  gas.  It  also  resists 
putrefaction  for  a  long  time,  so  that  the  two  bands  may  be  visible  for 
months  or  years,  whilst,  when  normal  blood  putrefies,  the  reduction  of 
oxy-h^emoglobin  occurs  at  once.  (Gamgee,  quoting  Hoppe-Seyler.) 
Blood  containing  carbonic-oxide-haemoglobin  gives  a  cinnabar  red 
precipitate  with  caustic  soda,  due  to  the  formation  of  a  compound  of 
carbonic  oxide  with  haematin.  The  gas  CO  can  displace  the  0  from 
oxy-haemogiobin.  It  is  well  known  that  carbonic  oxide,  given  off 
during  the  imperfect  combustion  of  carbon,  as  occurs  in  charcoal  stoves, 
is  a  powerftd.  poison,  soon  destroying  life.  This  it  does  by  combining 
with  the  haemoglobin  of  the  blood,  and  thus  interfering  with  the 
respiratory  functions  of  that  important  body. 

(b)  Nitric-oxide  Hcemoglobin. — AVhen  ammonia  is  added  to  blood,  and 
then  a  stream  of  nitric  oxide  is  passed  through  it,  this  compound  is 
formed  (Hermann),  and  it  may  be  obtained  in  a  crystalline  form  (iso- 
morphous)  "with  those  of  oxy-  and  carbonic-oxide-haemoglobin,  whilst  it 
also  has  a  similar  sj^ectrum.  A  stream  of  nitric  oxide  (NO)  can  dis- 
place carbonic  oxide  (CO)  from  the  carbonic-oxide-haemoglobin  in  blood, 
thus  sho"\Wng,  as  is  well  pointed  out  by  Dr.  Gamgee,  that  we  have 
three  compounds  of  htemoglobin  with  gases,  increasing  in  stability  in 

^  Dr.  Gamgee  gives  his  own  and  the  measurements  of  other  observers  at  p.  105 
of  Physiological  Chemistry,  vol.  i. 


THE  PIGMENTS.  125 

the  following  order :  Oxy-ligemoglobin,  carbonic-oxide-hseinoglobin,  and 
nitric-oxide-hsemoglobin. 

2.  HcBmochromogen. — Wben  bsemoglobin  is  acted  on  hj  acids  or 
alkalies  it  decomposes  into  hsematin,  a  substance  containing  the  iron, 
and  one  or  more  albuminous  bodies,  to  which  the  name  globulin  may 
be  given.  This,  however,  is  not  a  direct  decomposition,  but,  in  the 
presence  of  oxygen,  there  is  in  the  first  instance  oxidation,  with  the 
result  of  the  production  of  an  intermediate  body,  haemochromogen. 
The  oxidation  occurs  so  quickly  that  the  new  body  and  its  spectrum 
can  only  be  recognized  with  special  arrangements.  If,  however,  haemo- 
globin be  decomposed  in  an  apparatus  ^  from  which  oxygen  is  excluded, 
by  the  action  of  alcohol  containing  sulphiuric  acid  or  caustic  potash,  a 
purple-red  fluid  (in  alkaline  solutions)  is  obtained.  This  is  haemo- 
chromogen,  which,  by  oxidation,  yields  hsematin.  Hoppe-Seyler 
supposes  it  to  have  the  composition  Cg^HggN^FeOs,  ^^^1  gives  the 
equation — 

2(C34H36N,Fe05)   -f-   0,  =  C,^^,,-^,Ye.fi^,  +  2H2O. 
Haimochromogen.  Hsematin. 

It  is  really  a  product  of  the  decomposition  of  haemoglobin,  although 
it  is  erroneously  termed  reduced  hsematin  by  some  authors.  The 
sj)ectrum  of  this  substance,  seen  in  Plate  I.  8,  is  thus  described  by  Dr. 
MacMunn— 

"Obtained  from  blood  treated  by  rectified  spirit  and  ammonia  by  adding  sulphide 
of  ammonium.  The  second  band  varies  much  in  breadth,  the  iirst  being  much 
better  marked.  In  concentrated  solutions,  the  first  band  reads  A569  to  X542, 
and  the  second  band  X535  to  A.504.  More  diluted,  first  band,  X569  to  X542 — 
darkest  part,  X566  to  X549  ;  second  baud,  from  edge  to  edge,  \536'5  to  A506.  In 
a  still  more  dilute  solution,  they  read  :  First  band,  X566  to  A.547,  and  second 
band,  \535  to  \514.  If  we  distinguish  the  readings  of  the  extreme  edge  of  each 
band  from  the  darker  parts,  we  get :  First  band,  A567'5  to  A547,  and  the  darker 
part  from  A.564  to  X550'5  ;  the  second  band,  A.535  to  A514. " 

3.  MethcemogloUn. — This  is  a  substance  intermediate  between  haemo- 
globin and  oxy-haemoglobin,  and  it  would  appear  that  the  oxygen  it 
contains  is  more  firmly  united  to  haemoglobin  than  in  the  case  of  oxy- 
haemogiobin.  It  is  produced  when  a  solution  of  haemoglobin  has  been 
exposed  to  the  air  for  some  time,  when  it  becomes  acid  and  loses  its 
blood-red  colour,  acquiring  a  brownish  tinge,  and  the  spectrum,  as 
given  in  Plate  I.  4,  shows  two  absorption  bands  like  those  of  oxy- 
haemoglobin  and  a  new  band  in  the  red  near  C.  This  is  the  spectrum 
of  an  acid  solution.  If  this  be  now  rendered  alkaline  by  the  addition 
of  ammonia,  the  band  near  C  disappears,  and  another  fainter  band  is 

^  Apparatus  figured  La  Gamgee's  Physiological  Ghemistrij,  p.  119. 


1-2Q  THE  CHEMISTRY  OF  THE  BODY. 

seen  before  D.  (See  Plate  I.  5.)  On  comparing  the  spectra  4  and  5  in 
Plate  I.,  it  will  be  seen  also  that  the  position  of  the  band  corres])onding 
to  the  a-band  of  oxy-hsemoglobin,  that  is  the  one  immediately  to  the 
right  of  D,  is  moved  a  little  farther  to  the  right  in  the  spectrum  of 
alkaline  methaemoglobin.     Dr.  MacMunn  thus  descriljes  these  spectra — 

Methemocjlobin. — Prepared  by  acting  on  an  aqueous  solution  of  sheep's  blood 
with  a  solution  of  permanganate  of  potash  :  First  band,  \647  to  X6'22 — often  another 
feebler  band  may  be  observed  from  AGIO  to  \597  ;  second  band,  '\587  to  X571  ;  third 
band,  /\o52  to  /\532 ;  and  a  fourth  band  (?),  X514  to  X490.  Alkaline  methmnoijlohin. — 
Prepared  by  adding  a  little  ammonia  to  the  previous  solution  :  First  band,  X610 
to  X597  ;  second  baud,  XoS7  to  X5l}7"5 ;  third  band,  X552  to  X523." 

The  chief  interest  in  methsemoglobin  is  connected  with  the  facts  that 
if  the  alkaline  solution  be  shaken  up  with  sulphide  of  ammonium,  a 
solution  is  obtained  giving  the  spectrum  of  reduced  hajmoglobin,  and  if 
this  latter  solution  be  now  shaken  up  with  air,  oxy-hsemoglobin  is 
detected  by  its  bands  a  and  jB.  These  facts  were  first  observed  by  Dr. 
Arthur  Gamgee  in  his  well-kno"vvn  research  on  the  action  of  nitrites  on 
the  blood,  in  Avhich  he  showed  that  blood  mixed  with  nitx'ites  contained 
oxygen  that  Avas  not  removed  by  a  stream  of  carbonic  oxide,  nor  was 
given  up  to  a  vacuum,  and  he  believed  that  this  was  owing  to  some 
kind  of  combination  having  taken  place  between  the  haemoglobin  and 
the  nitrites.  Later  researches  have  supported  the  view  that  this 
nitrite-hsemoglobin  is  really  metheemoglobin.  This  substance  is  not  a 
hyperoxide  of  haemoglobin,  nor  a  per-oxyhsemoglobin,  because,  as 
shoAATi  by  Hoppe-Seyler,  it  may  be  formed  in  circumstances  in  Avhich 
oxidation  cannot  occur. 

4.  Hcematin,  C^^^^^eO-^  (or  tAvice  that  formula),  is  formed  along 
with  globulin  Avhen  haemoglobin  is  decomposed.  A  solution  may 
be  readily  made  by  adding  acetic  acid  to  blood.  The  blood  be- 
comes of  a  brownish  colour,  and  if  it  now  be  shaken  up  with 
ether,  the  latter  floats  to  the  top  and  an  ethereal  solution  of  acid 
haematin  is  obtained.  This  may  be  used  for  examination  Avith  the 
spectroscope,  or  the  ether  may  be  evaporated,  and  the  residue, 
haematin,  washed  AA'ith  ether,  alcohol,  and  Avater.  AVhen  so  obtained, 
it  is  a  reddish-broAvn  amorphous  poAvder,  having  a  metallic  lustre,  in- 
soluble in  water,  alcohol,  and  chloroform,  but  soluble  in  acidulated 
alcohol  and  alkalies.  The  spectroscopic  appearances  of  acid  haematin 
and  of  alkaline  haematin  are  given  in  Plate  I.  6  and  7.  With  acid 
haematin  four  bands  are  seen,  the  1st  in  the  red  betAveen  C  and  D ;  the 
2nd,  a  narroAV  faint  band  close  to  D ;  the  3rd,  a  broad  band  betAveen  D 
and  E ;  and  the  4th,  broad  and  faint,  between  h  and  F.  If  the  fluid  is 
made  alkaline  Avith  ammonia,  then  we  see  the  spectrum  of  alkaline 


THE  PIGMENTS.  127 

hsematin,  one  broad  absorption  band  near  D,  and  a  shaded  dark  part  of 
the  spectrum  from  a  little  to  the  left  of  E  to  midway  between  E  and  F, 
and  complete  absorption  beyond  this  boundary.  The  exact  details  as  to 
the  position  of  the  bands  are  thus  given  by  Dr.  MacMunn — 

"(1)  Acid  HcEmatin. — A  rectified  spirit  and  sulphuric  acid  filtered  extract 
from  sheep's  blood.  The  1st  band  from  X647  to  X605,  dark  part  X641  to 
A622;  2nd  band,  very  feeble  from  \593  to  X571  ;  3rd  band,  from  X550-5  to  X529  ; 
4th  band,  from  X517  to  X488  or  X485.  Prepared  in  the  usual  way  by  acting  on 
blood  with  acetic  acid,  and  shaking  with  ether,  the  ethereal  solution  gives  bands 
with  these  measurements  :  1st  band,  from  X656  to  X615 — darker  part  X647  to  X630  ; 
2nd  band,  from  X597  to  X577  ;  3rd  band,  from  X557  to  X529  ;  4th  band,  from  X517  to 
A488. 

(2)  J  IhxUne  Hcematin  got  by  adding  rectified  spirit  and  caustic  soda  to  blood  and 
filtering.  The  whole  band  extends  from  X630  to  X562 — the  darker  part  from  X619 
to  X581.  The  purer  form  of  alkaline  hasmatin  prepared  from  pure  hsematin  gives 
a  band,  when  examined  in  rectified  spirit,  from  X627'5  to  X562 — darker  part  from 
X619  toX581." 

A  substance  similar  to  hsematin  (entero-ha^matin)  occurs  in  the  bile  of  snails 
{Sorby),  and  in  that  of  the  limpet  and  cray  fish  (MacMunn). 

5.  Hmmatopm-phyrin  or  cruentin,  Cg<5H^2^8^i2>  ^^  ^  body  formed  by  the 
■decomposition  of  haematin.  When  the  latter  is  mixed  with  strong 
sulphuric  acid,  it  is  dissolved,  and  after  filtering  through  asbestos,  a  clear 
purple-red  solution  is  obtained.  (Gamgee,  op.  cit.)  If  water  be  now 
added  largely  to  this  solution  the  greater  part  of  the  dissolved  coloured 
substance  is  precipitated  as  a  brown  flocculent  mass,  and  the  amount  of 
this  is  increased  if  alkalies  be  added  to  neutralize  the  acid.  It  is  impor- 
tant to  note  that  in  this  decomposition  the  whole  of  the  iron  of  the 
hsematin  separates  and  is  found  in  the  solution  as  a  ferrous  salt.  Thus — 

C68H68N8Fe.,Oio  +  2(ES0d  +  0,= CggH^^NsOi^  +  2(FeS0J. 

Hasmatin.  Sulphuric  Hsematoporphyrin.  Sulphate  of 

acid.  iron. 

Hoppe-Seyler  has  obtained  hsematoporphyrin  by  the  action  of  nascent 
hydrogen  on  hsematin,  and  MacMunn  has  found  the  same  substance  by 
the  action  of  sodium  amalgam  on  hsematin.  The  precipitate  is  hsema- 
toporphyrin. Like  hsematin,  it  may  exist  in  either  an  acid  or  an  alka- 
line solution,  and  the  two  solutions  give  different  and  characteristic 
spectra.  Acid  hsematoporphyrin  gives  a  broad  dark  band  a  little  to  the 
right  of  D  (Plate  I.  9),  and  a  thin  faint  band  to  the  left  of  B.^  Alkaline 
hsematoporphyrin  (Plate  I.  10)  gives  four  bands  :  1st,  thin  and  narrow 
between  C  and  D ;  2nd,  a  broader  band  near  to  D ;  3rd,  another  broad 

2  Gamgee  states,  "  The  first  (solution  in  strong  sulphuric  acid)  exhibits  a  pretty 
dark  band  immediately  below  D  and  a  sharply-defined  band  nearly  intermediate 
between  D  and  E."     (Gamgee,  Physiol.  Chem.  p.  117.) 


128  THE  CHEMISTRY  OF  THE  BODY. 

band  near  E ;    and  4tli,  a  "well  marked  dark  hand  between  h  and  /'. 
The  exact  position  of  the  bands  is  thus  stated  by  Dr.  MacMunn — 

"  (1)  Acid  Hamatoporphyrin. — Id  concentrated  solution  in  sulphuric  acid  the 
bands  read  :  1st  band,  X607'5  to  X593  ;  2nd  band,  X5S5  to  X536'5.  In  a  weaker 
solution  :  1st  band,  X605  to  X593  ;  2nd  band  or  shading,  from  X5S5  to  the  next  band 
which  extends  from  \o67'5  to  Xo-lO.  If  the  fluid  be  diluted  by  adding  a  little  recti- 
fied spirit  to  the  sulphuric  acid  instead  of  adding  acid,  the  bands  read  :  1st  band, 
X610  to  X591— darker  part  from  X605  to  X593  ;  2nd  band  or  shading,  X585  to  X567*5  ; 
and  dark  band,  X567  '5  to  X540.  For  the  bands  of  jmre  acid  hsematoporphyrin  in 
rectified  spirit  and  sulphuric  acid  the  following  are  the  measurements  :  1st  band, 
X605  to  X591  ;  2nd,  a  shading  from  X5S3  to  X564  ;  3rd  band,  X564  to  X542. 

(2)  Alkaline  Hcematoporphyrin. — In  solutions  of  this  pigment,  the  edges  of  bands 
vary  much  according  to  concentration.  The  folloM'ing  may  be  taken  to  apply  to  a 
solution  of  mean  concentration  :  1st  band,  X633  to  X612"5,  and  dark  from  X630  to 
X615 ;  2nd  band,  X5S9  to  X.564,  and  a  shading  before  this  which  is  most  difficult  to 
measure,  and  may  be  from  X605  to  X589  ;  3rd  band,  X549  to  X529,  which  is  the 
darker  part ;  4th  band,  X518'5  to  X4S8." 

MacMunn  has  found  hsematojDorphyrin  in  the  intcgximent  of  Uraster 
rubens  (star  fish),i  in  the  integument  of  Limao:  flavus,  Limax  variegatus,  and 
in  Atrion  ater  (slugs),  in  common  earth  Avorm,  Lnmhricus  terresfris,  in  Sole- 
curtus  strigillatus,  and  he  shows  that  polyperythrin,  a  pigment  discovered 
by  Moseley  in  various  actiniae  and  deep-sea  polypes,  is  probably  identical 
■with  hsematoporphyrin.  It  is  also  found  in  the  eggshells  of  some  birds. 
A  land  of  haematoporphyrin  also  appears  in  the  urine  of  cases  of  Addi- 
son's disease,  of  acute  rheumatism,  and  other  diseases. 

Dr.  MacMunn  -  has  found  in  A-'arious  common  species  of  actinia,  A . 
mesemhryanthemum,  Bunodes  crasskomis,  Sagartia  bellis,  etc.,  a  colouring 
matter  related  to  haemoglobin,  very  similar  to  htemochromogen,  and 
convertible  into  hfematoporphyrin. 

6.  Hcematolin,  Cg^H^gNgO;,  is  another  derivative  of  haematin  described 
by  Hoppe-Seyler.  It  is  insoluble  in  sulphuric  acid  and  in  caustic  lyes, 
thus  differing  from  hsematoporphyrin. 

7.  Hccmatoldin. — In  old  blood  clots  such  as  occur  in  the  brain,  in  the 
corpora  lutea  of  the  ovary,  and  in  the  coagiila  of  aneurisms,  crystals  of 
this  substance  are  found  in  the  form  of  regular  or  oblique  rhombs  or 
rhomboids  (Fig.  52).  The  crystals  are  strongly  refractive  and  trans- 
lucent, of  a  brick-red  or  yelloAvish-red  colour.  They  are  insoluble  in 
water,  alcohol,  ether,  acetic  acid,  and  the  dilute  acids  and  alkalies. 
Caustic  potash  gives  a  bright  red  at  first  and  then  the  crystals  dissolve. 

1  MacMunn,  Quart.  Jour,  of  Micros.  Science,  \811.  Mso  Journal  of  Physiology, 
vol.  vii.  See  also  MacMunn  on  the  haematoporphyrin  of  Solecurtus  strigillatus. 
Jour,  of  Physiology,  vol.  viii.  No.  6. 

-MaclMunn,  Pliil.  Trans,  of  Royal  Society,  1885. 


TEE  PIGMENTS. 


129 


Concentrated  acids  and  fuming  nitric  acid  give  a  play  of  colours  Anth. 
crystals  of  hsematoidin  like  the  reaction  of  ♦    ^ 

these  acids  -with  the  colouring  matter  of  the 
bile,  the  bodies  gradually  becoming  brownish- 
red,  green,  blue,  rose-coloured,  and  finally 
yellow.  Haematoidin  is  also  said  to  appear  in 
a  granular  form.     (Eobin.) 

There  has  been  much  discussion  as  to  the 
true  nature  of  haematoidin,  some  asserting 
that  it  is  identical  with  bilirubin,  one  of  the 
pigments  of  the  bile  to  be  hereafter  described, 
while  many  others— Holm  and  Staedeler—  ^^°-  s^.-Crystais  of  H«matoidin 
on  the  ground  of  differences  in  chemical  reactions,  and  Preyer,  from 
differences  in  the  spectra,  have  denied  the  identity.^ 


Fig.  53. — 1.  Hcemin  crystals  from  man — whetstone  form; 
2.  Crystals  of  common  salt ;  3.  Hasmatoidin  crystals 
from  man,  500  diameters. 

8.  Hcemin,  C^gilj^^Ye^O^^,  is  a  derivative  of  hsematin,  the  appearance 
of  Avhich  is  an  important  test  for  the  presence  of  this  substance,  or  in 
other  words,  of  blood,  in  medico-legal  inc^uiries. 
Sometimes  termed  Teichmann's  crystals,  they 
are  rhombohedral  plates  or  six-sided  plates,  of 
a  brownish  colour  by  transmitted  light  (Fig. 
54).  They  are  insoluble  in  water,  soluble  in 
hot  alcohol,  in  hot  ether,  and  in  caustic  potash. 
To  obtain  them,  add  to  a  drop  of  blood  on  a 
glass  slide  a  few  particles  of  common  salt,  and 
then  a  drop  of  glacial  acetic  acid ;  place  the 
slide  in  a  warm  place,  or  heat  cautiously  over 
the  flame  of  a  spirit  lamp,  and  then  examine 
with  the  microscope.  The  crystals  will  then 
be  found  as  represented  in  Fig.  53,  probably 
mixed  with  a  few  crystals  of  common  salt. 


Fig.  54. — Crystals  of  Hasmin.  The 
vie'w  in  Fig.  63  is  more  like  what 
one  may  readily  obtain  from  a 
drop  of  blood. 


^  See  on  this  point  Gamgee's  Physiolocj.  Chem.  p. 
Patlwlogy,  p.  313. 


120,  and  Wagner's  General 


130 


THE  CHEMISTRY  OF  THE  BODY 


B. — The  Pigments  of  the  Bilk. 

The  bile  of  mammals  contains  two  chief  pigments,  bilirubin  and 
biliverdin.  From  these,  certain  other  pigmentary  bodies  may  be 
derived.  The  general  relation  of  these  pigments  may  be  sho^\^l  in  the 
first  instance  by  contrasting  their  empirical  formula?  as  follows — 


Derivatives 


Bilirubin,  - 
Biliverdin,  - 
Choletelin,  - 
Bilifuscin,  - 
Bilipvasiu,  - 
Hydrobilinibin,  - 


CeHisKA 
^"leHisNaOg 

Cj6H,oN204 

C32H40N4O7 


1.  JBilirvbin,  CigHigX^Og,  or  Cg^H^gN^Og,  may  be  obtained  from  fresh 
bile  by  acidulating  and  then  shaking  up  with  chloroform.  The  latter 
dissolves  the  bilirubin,  and  on  draAving  off  the  chloroform  solution  and 
evaporating  it  the  coloiu-ing  matter  remains. 
It  may  be  purified  by  being  treated  ^Yiih.  alcohol. 
Bilirubin  is  either  a  reddish-orange  amorphous 
powder  or  it  may  be  found  in  the  form  of  dark 
red  needle-shaped  or  rhombohedral  crystals 
(Fig.  5.5).  These  are  insoluble  in  water,  slightly 
solul)le  in  alcohol  or  ether,  and  readily  soluble 
in  chloroform,  benzin,  bisulphide  of  carbon, 
sulphuric  acid,  and  the  alkalies.  Bilirubin, 
bj"  oxidation,  becomes  changed  into  biliverdin 
and  choletelin,  and  during  the  oxidation  other 
transitory  bodies  are  formed,  some  of  Avhich 
On  this  fact  depends  Gmelin's  reaction  or  test, 
used  for  the  detection  of  the  bile  in  the  lu-ine.  A  few  drops  of  bile  are 
spread  out  on  a  white  porcelain  plate,  and  a  drop  of  fuming  nitric  acid 
(nitric  acid  containing  nitrous  acid)  is  allowed  to  fall  into  the  middle  of 
the  fluid  film.  At  the  point  of  contact  of  the  two  fluids,  beautiful  rings 
of  colour  appear  in  the  follo^^-ing  order  :  green,  blue,  violet,  red,  and 
yellow.  If  biliverdin  alone  is  present,  the  play  of  colours  begins  "with 
the  blue.  The  spectrum  of  the  chloroform  solution  of  bilirubin  shows 
no  absorption  bands  ;  only  an  absorption  of  the  ^dolet  end  of  the 
spectrum  to  b.  (See  plate  I.  13.)  A  solution  that  shows  Gmelin's 
reaction,  when  examined  spectroscopically,  gives  "  a  broad  shading 
(probably  composed  of  two  distinct  bands)  in  orange  and  yellow,  and  a 
black  band  extending  from  near  b  to  beyond  i^.  ...  In  a  very 
short  time  the  shading  in  orange  begins  to  fade,  and  at  the  time  the 
oxidation  process  is  completed  and  the  colour  of  the  solution  has  become 


Fig.  5u. — Crystals  of  bilirubin. 

have  not  been  isolated. 


THE  PIGMENTS,  131 

yellow,    nothing   hut   the   band   at   F  is   left."      (MacMunn,    op.    cit. 
p.  160.) 

Whilst  bilirubin  has  never  been  obtained  artificially  by  the  chemist 
from  the  decomposition  of  haemoglobin,  there  are  strong  grounds  for 
holding  that  in  the  body,  and  probably  in  the  cells  of  the  liver,  this 
transformation  occurs.  The  injection  into  the  blood  of  substances  that 
destroy  the  red  blood  corpuscles,  such  as  large  quantities  of  water,  the 
bile  acids,  or  ammonia,  is  followed  by  the  excretion  of  bilirubin  in  the 
urine  ;  therefore  it  is  fair  to  infer  that  the  increased  amount  of  bilirubin 
has  come  from  the  breaking  up  of  haemoglobin.  As,  however,  the 
direct  injection  of  a  solution  of  hsemoglobin  into  the  blood  does  not 
cause  an  increase  of  urinary  pigment,  it  is  evident  that  the  chemical 
transformations  are  not  yet  understood.^ 

2.  Biliverdin,  C-^j-H-^giSr^O^,  the  chief  pigment  in  the  bile  of  herbivora, 
may  be  made  by  exposing  greenish  bile  for  some  time  to  the  air.  The 
addition  of  hydrochloric  acid  throws  down  green  flaky  masses,  amor- 
phous, insoluble  in  water,  but  soluble  in  alcohol.  The  alcoholic  solu- 
tion has  a  deep  green  colour,  and  on  evaporation  an  amorphous  residue 
is  obtained,  soluble  in  glacial  acetic  acid,  and  the  evaporation  of  the 
acetic  acid  solution  yields  biliverdin.  (Beaunis.)  It  is  then  found  to  l^e 
an  amorphous  powder,  insoluble  in  water,  ether,  and  chloroform,  but 
soluble  in  alcohol  and  sulphuric  acid.  Biliverdin  is  undoubtedly  formed 
by  the  oxidation  of  bilirubin. 

A  substance  like  biliverdin  has  been  fovind.  by  MacMunn  in  various  actiniae,  and 
by  Krukenberg  in  the  shells  of  certain  molluscs.  MacMunn  believes  it  may  be 
looked  on  as  excretory,  being  probably  derived  from  other  pigments  like  htemo- 
globin,  or  from  those  he  terms  histohfematins,  pigments  scattered  through  the 
tissues. 

3.  Choletelin,  C^gH-i^glSr^Oc,,  is  an  oxidation  product  of  biliverdin,  or  it 
may  be  regarded  as  the  substance  formed  at  the  end  of  the  oxidation 
process  of  bilirubin.  It  is  prepared  by  passing  nitrous  vapours  into  an 
alcoholic  solution  of  bilirubin.  When  the  alcoholic  solution  is  poured 
into  water,  flakes  of  choletelin  "  of  the  colour  of  ferric  oxide  "  separate, 
and  these,  by  evaporation,  may  be  obtained  as  a  dry  powder.  "  Chole- 
telin cannot  be  made  to  crystallize  from  any  solvent.  It  dissolves  very 
easily  in  the  fixed  alkalies,  and  their  carbonates,  also  in  ammonia, 
forming  brown  solutions,  from  which  it  is  precipitated  in  flocks  by  acids. 
It  is  soluble  in  alcohol,  ether,  and  chloroform.      The  alcoholic  solution 

^It  is  significant  that  urobilin  can  be  obtained  from  haemoglobin  and  haematin, 
and  from  bilirubin  by  the  action  of  reducing  agents.  (See  below.)  Moreover,  after 
blood  has  been  extravasated  in  large  quantity  into  the  tissues,  the  urobilin  of  the 
urine  is  much  increased. 


132  THE  CHEMISTRY  OF  THE  BODY. 

is  precipitated  by  -water.  With  silver  nitrate,  it  gives  a  precipitate  only 
on  the  addition  of  ammonia.  No  pcrceptililc  reaction  is  produced  by 
hydrogen  sulphide,  or  b}-  zinc  and  hydrochloric  acid."  ^  It  does  not 
give  Gmelin's  reaction,  as  it  has  been  oxidized  beyond  that  stage.  The 
spectrum  of  a  similar  pigment,  to  which  the  bands  in  ox  and  sheep  bile 
are  due,  is  shown  in  Plate  I.  12,  and  is  thus  described  hy  Dr. 
MacMunn — 

"  Cholohcematin,  from  bile  of  sheep.  The  bile  is,  after  addition  of 
absolute  alcohol  and  acetic  acid  and  filtering,  agitated  in  a  tap  funnel 
Avith  chloroform,  which,  after  separation,  shows  this  spectrum.  On 
letting  the  chloroform  stand  for  a  day  or  so,  a  urobilin  band  also 
generally  becomes  visible.  (1)  The  lile  itself — 1st  band,  centre  at  A649 
(not  shown  in  plate);  2nd  band,  A613  to  /\585  ;  3rd  band,  A.577"5  to 
A561-5;  4th  band,  A537  to  A521-5  (?).  Bands  2,  3,  and  4  shown  in 
plate. 

"(2)  Chlcyroform  sohition — 1st  band,  A654  to  A636  ;  2nd  band,  A607  to 
A580-5  ;  3rd  band,  A.572  to  A.560  ;  4th  band,  A536  to  A516.  Bands  2, 
3,  and  4  shown  in  plate."  ^ 

4.  Bilifuscin,  C^oH.^oN.fi^,  may  be  obtained  from  brown  gall  stones 
from  the  human  being.  By  means  of  ether,  cholesterin  is  removed 
from  the  powdered  gall  stone,  and  the  powder  is  then  treated  with 
Avater  and  a  little  hydrochloric  acid.  It  is  then  thoroughly  washed 
with  water  to  remove  all  the  acid,  next  extracted  with  boiling  ether  to 
remove  fatty  acids,  and  finally  boiled  Avith  absolute  alcohol.  On  evapor- 
ating the  alcoholic  solution,  bilifuscin  appears  as  a  dark  brown  powder, 
or  a  black  brittle  mass.'^  By  a  somewhat  similar  process.  Simony  has 
extracted  it  from  human  bile.*  It  does  not  give  Gmelin's  reaction.  It 
is  readily  soluble  in  alcohol,  glacial  acetic  acid,  and  alkalies  ;  sparingly 
soluble  in  chloroform,  but  insoluble  in  water,  ether,  and  dilute  acids. 
The  alcoholic  solution  absorbs  the  violet  and  indigo-blue  parts  of  the 
spectrum. 

5.  BUiprasin,  C-^^.-,^^0^^,  is  the  name  given  by  Staedeler  to  a  green 
pigment  obtained  from  gall  stones.  By  exhausting  the  gall  stones  with 
ether,  hot  water,  chloroform,  and  dilute  hydrochloric  acid,  he  obtained  a 
brownish-green  residue,  from  which  chloroform  dissolved  a  broAvn  pig- 
ment (bilifuscin)  and  some  bilirubin,  whilst  the  undissolved  residue 
gave  to  alcohol  biliprasin.     Its  spectrum  has  not  been  studied. 

1  Watt's  D/c^.  of  Chem.,  Bile  Pigments,  vol.  vii.  p.  189.  Quoted  from  Maly 
and  Heynsius  and  Campbell. 

2  See  Jour.  Physiol,  vol.  vi.  Nos.  1  and  2,  p.  24. 
'  Dr.  Thudichum's  Chemical  Physiology,  1872. 

■»  Watt's  Diet,  of  Chem.  vol.  viii.  p.  325. 


THE  PIGMENTS,  133 

6.  Bilicyanin,  a  blue  pigment,  may  be  obtained  by  adding  an  alcobolic 
solution  of  bromine  to  bilirubin  suspended  in  chloroform.  On  evapora- 
tion the  liquid  assumes  a  blue  colour,  and  on  complete  evaporation 
"there  remains  a  shining  dark  mass,  which  appears  green  when  spread 
in  a  thin  layer  upon  porcelain,  but  dissolves  with  a  splendid  blue  colour 
in  alcohol.  It  is  less  soluble  in  ether,  but  more  freely  in  ether-alcohol."  ^ 
It  gives  two  or  perhaps  three  absorption  bands  in  the  yellow  and  in  the 
green. 

7.  Another  blue  colouring  matter  has  been  separated  from  the  bile 
of  man  and  of  the  ox,  sheep,  pig,  dog,  and  cat  by  E.  Ritter,  to  which  no 
name  has  been  given.  Bile  is  shaken  with  chloroform  till  a  yellow 
solution  is  obtained.  This  solution  is  treated  with  carbonate  of  soda  till 
the  yellow  colour  disappears.  On  neutralization  with  hydrochloric  acid, 
two  layers  are  formed,  one  the  yellow  chloroform  solution  and  the  other 
the  blue  pigment.  This  pigment  is  insoluble  in  acids  and  chloroform  ■ 
it  dissolves  in  alkalies,  and  when  the  alkaline  solution  is  neutralized 
with  acids  and  exposed  to  air,  a  brown  precipitate  is  formed,  which 
becomes  blue  in  a  few  days  or  only  after  a  month,  thus  differing  from 
an  alkaline  solution  of  reduced  indigo  which  instantly  turns  blue  on 
exposure  to  the  air. 

8.  Bililiumin  is  a  name  given  by  Staedeler  to  a  humus-like  residue  left 
after  exhausting  gall  stones  with  water,  alcohol,  ether,  chloroform,  and 
dilute  acid  successively.     It  is  probably  impure  biliverdin  and  mucus.^ 

9.  Reducible  Product  of  the  Oxidation  of  the  Bile  Pigment. — The  following 
account  of  this  substance  from  the  paper  on  the  subject  by  Stokvis  is 
given  in  Watt's  Dictionary  of  Chemistry,  vol.  vii.  p.  189  — 

"  The  substance  is  formed  as  a  secondary  product  in  most  cases  of  the  oxidation 
of  biliary  colouring  matter,  whereby  Gmelin's  reaction  is  produced.  It  is  colour- 
less, or  of  a  light  yellow  tint,  and  is  soluble  in  water,  alcohol,  and  dilute  acids. 
It  becomes  of  a  beautiful  rose-red  colour  when  boiled  with  reducing  agents  in 
alkaline  solutions.  The  red  solution  gives  in  the  spectrum  a  tolerably  broad 
absorption  band  in  the  green.  In  concentrated  solutions  (thick  strata)  the  band 
begins  close  on  the  line  D  and  extends  to  h.  In  dilute  solutions  (thin  strata)  it 
occupies  only  two  thirds  of  the  space  between  D  and  E,  ending  short  of  E. 
Shaking  with  air  causes  both  the  rose  colour  and  the  absorption  band  to  disappear. 
This  bye-product  differs  from  the  bile  colouring  matter  and  other  oxidation  pro- 
ducts of  the  same,  in  being  insoluble  in  chloroform  and  ether  and  in  not  forming 

^  Watt's  Diet,  of  Ghem.  vol.  vii.  p.  188,  quoting  from  Heynsius  and  Campbell. 
See  also  Dr.  MacMunn,  op.  cit.  p.  152. 

-  For  an  account  of  Dr.  Thudichum's  views  as  to  the  pigments  of  the  bile,  see  his 
Tenth  Report  of  the  Medical  Officer  of  the  Privy  Council)  1867  ;  also  his  Chemical 
Physiology ;  also  MacMunn's  Spectroscope  in  Medicine,  p.  154.  Dr.  MacMuun 
also  gives  an  account  of  the  spectra  of  the  bile  of  various  animals. 


134.  THE  CHEMISTRY  OF  THE  BODV. 

iasoluble  compounds  with  neutral  or  basic  lead  acetate.  It  is  precipitated  how- 
ever by  ammonia  and  basic  lead  acetate.  This  substance  exists  as  such  in  the 
gall  stones  both  of  man  and  of  the  ox.  It  can  be  obtained  from  them  by  simply 
boiling  with  distilled  water  and  extraction  by  dilute  acids.  It  does  not  exist  in 
fresh  bile.  It  occurs  in  the  urine  of  animals  which  have  been  starved  for  some 
days  previously,  in  icteric  urine,  and  in  the  urine  of  febrile  diseases,  such  as  small- 
pox, typhus,  etc.  It  is  not  found  in  healtliy  urine.  It  seems  to  be  present  in  the 
alimentary  canal,  although  in  direct  experiments  with  different  kinds  of  food  little 
or  none  could  be  found.  In  alkaline  solutions  it  soon  loses  its  characteristic  pro- 
perties. Its  occurrence  in  any  liquid  of  neutral  or  acid  reaction  affords  an  indica- 
tion of  the  previous  existence  of  bile  pigment  therein.  In  applying  the  test,  the 
liquid  is  to  be  precipitated  with  lead  acetate,  excess  of  lead  removed  by  oxalic 
acid,  and  the  filtrate  concentrated  and  boiled  with  alkalies  and  a  reducing  agent. 
If  no  reduction  takes  place,  and  if  the  other  tests  for  biliary  colouring  matter  have 
given  a  negative  result,  their  absence  may  be  safely  inferred." 

C. — The  Pigments  of  the  Urixe. 

The  urine  contains  at  least  two  pigments,  urobilin  and  indigo-blue, 
derived  from  indican.  Thudiclium  describes  a  third,  named  urochrome, 
which  by  oxidation  becomes  uroerythrin.^ 

1.  Urobilin,  CogH^oN^O^,  is  believed  to  be  closely  related  to  bilirubin, 
and  it  may  be  termed  hyclrobiliruUn.  When  bilirubin  is  dissolved  in 
dilute  potash  lye,  and  sodium  amalgam  added,  air  being  excluded,  no 
hydrogen  is  evolved,  the  dark  brown  fluid  becomes  lighter  in  colour,  in 
the  course  of  a  few  days  becoming  yellow  or  brownish-yellow,  and  then 
hydrogen  is  given  off".  Hydrochloric  acid  added  to  this  solution  sepa- 
rates a  pigment  of  weak  acid  reaction,  which  is  soluble  in  alcohol,  slightly 
in  water,  readily  in  ammonia  and  fixed  alkalies,  and  in  ether,  glacial 
acetic  acid  and  chloroform.  This  substance  contains  about  1  -5  per  cent, 
less  of  carbon  and  about  1  -5  per  cent,  more  of  hydrogen,  and  therefore 
it  may  be  called  hijdrohiliruhin.     Thus — 

2(Ci6Hi3No03)       +       H,      +      H,0      :=      C32H,oN40, 

Bilirubin.  Hydro-bilirubiii  or  urobilin. 

Biliverdin  Avith  sodium  amalgam  behaves  in  a  corresponding  way. 
There  is  every  reason  to  believe  that  in  the  intestines  a  portion  of  these 
liile  pigments  is  changed  into  hydrobilirubin,  Avhich  is  then  absorbed 
and  excreted  by  the  kidneys  as  urobilin.  Urobilin  is  a  dark  reddish- 
Ijrown  powder,  soluble  in  water  and  alcohol,  less  soluble  in  ether.  It 
forms  a  reddish  yellow  solution  in  chloroform.  With  chloride  of  zinc 
and  ammonia  it  gives  a  rose-coloured  solution,  -svith  green  fluorescence. 
This  substance  gives  a  characteristic  spectrum,  seen  in  Plate  I.  1 4,  which 
is  thus  described  by  Dr.  MacMunn — 

^  This  statement  has  however  been  disproved. 


THE  PIGMENTS.  135 

' '  Spectrum  of  urobilin  from  normal  urine  thus  prepared :  The  urine  is  pre- 
cipitated with  neutral  and  basic  acetate  of  lead,  the  precipitate  separated  by 
filtering,  decomposed  by  rectified  spirit  containing  sulphuric  acid ;  this  extract 
filtered,  diluted  with  water,  and  agitated  in  a  tap-funnel  with  chloroform ;  the 
chloroform  separated  off,  filtered,  evaporated,  and  the  brownish  residue  redissolved 
in  rectified  spirit.  Febrile  urobilin  differs  from  this  in  the  greater  shading  and 
breadth  of  band  and  in  other  slight  particulars.  Stercobilin,  found  in  fasces,  also 
differs  from  it." 

It  will  be  seen  that  there  is  a  distinct  broad  band  a  little  to  the  left  of  F. 
In  Plate  I.  15  the  spectrum  is  shown  of  the  same  solution  with  the 
addition  of  ammonia  and  chloride  of  zinc  and  filtered.  Here  the  band 
is  narrower  and  fainter,  and  less  of  the  blue  is  visible.  Dr.  MacMunn 
gives  the  position  of  the  absorption  band,  thus — "(1)  Chloroform  solu- 
tion, A  504  to  A  481 ;  (2)  Rectified  spirit  solution,  A  504  to  A  481 ; 
(3)  with  zinc,  chloride  and  ammonia,  A512"5  to  A  496."  The  band  is 
specially  well  marked  in  febrile  urines,  but  Dr.  MacMunn  asserts  that 
urobilin  is  invariably  present  in  normal  human  urine,  although  the 
quantity  may  be  so  small  that  the  absorption  band  cannot  be  detected 
unless  the  urine  has  been  subjected  to  the  treatment  with  acetate  of 
lead  above  described,  or  oxidized  by  means  of  permanganate  of  potash 
or  bromine  water.  According  to  Disqu6,  there  is  a  colourless  form 
of  urobilin  in  urine  which  may  be  called  reduced  urobilin,  i.e.  a 
ehromogen,  which  gives  no  absorption  spectrum.  This,  he  says,  may  be 
readily  changed  into  urobilin  by  oxidation,^  either  in  the  intestine  or 
during  the  passage  of  the  ehromogen  from  the  intestine  to  the  kidneys. 
There  is  no  strong  evidence  for  the  existence  of  this  substance. 

2.  Derivatives  of  Indican. — By  decomposition  indican  may  give  rise  to 
leucin,  volatile  fatty  acids,  and  a  reddish  colouring  matter,  indigo -red,  the 
indigruhin  of  Schunck,  the  urrhodin  of  Heller.  Sometimes,  also,  indican 
inthe  ^xrine  m-Sij  gire  rise  to  indigo-Uue.  (Seep.  109.)  The  uroxanthin  of 
Heller  appears  to  be  indican.  If  the  urine  of  cases  of  cancer  of  the 
liver,  or  of  obstruction  of  the  great  intestine,  be  allowed  to  stand  until 
putrefaction  occiurs,  an  irridescent  pellicle  forms,  which  yields  small 
crystals  of  indigotin,  and  the  fluid  may  become  blue.  Indigo-blue  also 
may  be  obtained  from  most  specimens  of  normal  urine,  and  quite  easily 
from  the  urine  of  the  horse,  by  mixing  the  urine  with  an  equal  volume 
of  strong  hydrochloric  acid,  then  adding  a  solution  of  hypochlorite  of 
calcium  till  a  blue  colour  appears,  and,  lastly,  shaking  up  with  chloro- 
form.     A  blue  chloroform  solution  of  indigo-blue  is  thus  obtained 

1  Ludwig  Disque.  Ueber  Urobilin.  Zeitschrift  fiir  Physiol.  CJhemie,  Band  ii.  1878. 
Hoppe-Seyler  has  obtained  urobilin  by  the  action  of  tin  and  hydrochloric  acid  on 
haemoglobin  or  hsematin. — Handhuch  der  Phydol.  vnd  Pathol.  C'hejn.  Analyse, 
s.  214. 


136  THE  CHEMISTRY  OF  THE  BODY. 

The  spectrum  of  this   sohition  is  shown  in    Plate  I.  16,  and  is  thus 
described  by  Dr.  ]Mac]\Iunn — 

"  Spectrum  of  indirjo-hlue  from  normal  urine.  The  urine  is  boiled  with  about 
a  third  of  its  bulk  of  hydrochloric  acid,  cooled,  iind  agitated  with  chloroform, 
which  shows  this  spectrum,  and  also — although  not  here  shown — a  band  at  F,  due 
to  urobilin.  The  band  before  D  is  due  pi'obably  only  to  the  blue  constituent, 
indiijo-hlue,  whilst  that  after  D  is  probably  due  to  the  rechlish  constituent,  for 
this  reason  that  the  bluer  the  solution  the  deeper  is  the  band  before  D,  while  the 
more  it  approaches  violet  the  darker  is  the  band  after  D.  This  test  for  the  pre- 
sence of  indican  will  detect  it  when  Jaffe's  hypochlorite  of  calcium  test  fails. 
Normal  urine  can  generally  be  made  to  show  the  presence  of  indican  by  its 
means." 

3.  Urohcematoporphi/rin,  or  urohcematin,  is  a  pigment  found  Ijy  Dr. 
MacMium  in  the  urine  of  cases  of  rheumatic  fever  and  of  Addison's 
disease.  He  believes  it  to  be  nearly  related  to  the  body  prepared  by 
Nencki  and  Sieber  by  the  action  of  tin  and  hydrochloric  acid  on  hsematin. 
The  alcoholic  solution  gives  the  follo■\^^ng  spectrum — "  1st  band, 
A595  to  A587;  2nd  band,  A.576  to  A.566  ;  3rd  band,  A557  to  A.541-.5; 
and  4th  band,  A.503  to  482-5."' ' 

4.  Urochroine,  a  substance  described  by  Dr.  Thudichum  is  said  to  be 
an  amorphous  substance  of  a  yellow  colour,  easily  soluble  in  water,  less 
so  in  ether,  very  dilute  acids,  and  alkalies,  and  least  of  all  in  alcohol.- 

5.  Vromdanin  is  another  dark  pigment  separated  by  Dr.  Thudichum 
from  urine  by  the  action  of  strong  sulphuric  acid.  Its  existence  as  an 
independent  pigment  is  more  than  doubtful.'' 

D. — Pigment  of  the  F^ces. 

In  addition  to  the  ordinary  pigments  of  the  bile,  some  of  which  are 
voided  in  the  faeces,  a  variety  of  urobilin,  to  which  the  name  stercohilin  has 
been  given,  has  been  examined  by  Dr.  MacMunn.  He  states  that  there 
is  scarcely  any  difference  between  the  urobilin  fomid  in  the  lurine  of 
febrile  patients  and  the  stercobilin  of  human  faeces ;  but  that  there  is 
a  distinct  difference  in  the  spectrum  of  ordinar}'  lu'obilin  and  sterco- 
bilin.'^ By  covering  faeces  with  absolute  alcohol,  chloroform,  ether, 
rectified  spirit,  and  sulphuric  acid  (1  in  15),  and  Avater,  solutions  Avere 
obtained  Avhich  gave  the  folloAving  results  Avith  the  spectroscope — [1] 
Alcohol  solution,  1  broad  band  from  A.506  to  A482-5  ;  (2)  Avith  caustic 

1(7/.  C.  le  Xobel,  Archlrf.  d.  ges.  Phys.  B.  xl.  1SS7. 
-  Thudichum,  Brit.  Med.  Journal,  186-4. 

3  For  an  account  of  it  see  Watt's  Diet,  of  Chem.,  1st  supplement,  p.  1120;  and 
cf.  Hoppe-Seyler,  Handhuchf.  Physiol,  und  Path.  Chem.  Analyse,  Vierte  Aufiage. 
^  MacMunn,  Journil  of  Physiology,  \o\.  vi.  Nos.  1  and  2. 


THE  PIGMENTS.  137 

soda,  A521"5  to  A505;  (3)  vvdth  zinc  chloride  alone,  1  band  A517"5  to 
A501.  [2]  Ether  solution,  1  band  which,  A\dth  acetic  acid,  extends  from 
A504  to  A482-5.  [3]  Chloroform  solution,  A507  to  A486-5.  (Compare 
this  with  the  description  of  the  spectrum  of  normal  urobilin,  given  at 
p.  135.)  On  evaporating  the  chloroform  solution  in  the  water  bath, 
Dr.  MacMunn  obtained  a  brown  amorphous  residue,  which  gave 
practically  almost  all  the  characters  of  febrile  urobilin  both  as  to 
solubility  and  spectrum.  In  none  of  the  solutions  did  he  detect  un- 
changed bile  pigments.  If  febrile  urobilin  and  stercobilin  were  the 
same,  then  the  amount  of  the  former  found  in  the  urine  woidd  be  the 
measure  of  the  amount  of  the  latter  absorbed  from  the  alimentary 
canal,  a  fact  of  considerable  clinical  importance.  Dr.  MacMunn  thus 
sums  up  our  knowledge  of  the  relation  of  the  urinary  fascal  and  bile 
pigments- — • 

"  It  would  appear  that  the  stercobilin  resulting  from  the  putrefactive  processes 
in  the  intestine,  and  accompanied  by  imperfectly  changed  biliary  pigments,  is 
taken  up  by  the  branches  of  the  portal  vein  and  carried  into  the  liver,  where  it  is 
probably  again  changed  by  the  action  of  a  ferment  into  a  chromogen.  A  portion 
of  this  chromogen  gets  into  the  blood  and  is  excreted  by  the  urine  as  a  chromo- 
gen. A  portion  may  escape  in  the  condition  of  biliary  urobilin  as  such,  and 
appear  in  the  urine  in  a  further  oxidized  condition  or,  owing  to  disturbance  of 
circulation  in  the  liver,  a  large  portion  of  unchanged  biliary  urobilin  may  appear 
in  the  urine.  Besides  this,  the  urine  under  certain  conditions  may  contain  a 
pigment  that  has  no  biliary  origin,  and  may  be  derived  entirely  from  htematin ; 
while,  in  certain  diseased  states  a  reduction  product  of  hsematin,  having  no  con- 
nection with  bilirubin  or  biliverdin,  and  closely  related  to  hEematoporphyrin, 
may  appear  in  the  urine  and,  to  a  great  extent,  if  not  altogether,  may  replace 
urobilin.  "1 

E. — Pigments  of  the  Tissctes. 

1.  The  Histohcematins  are  a  class  of  pigments  probably  first  detected 
by  Dr.  Sorby,  but  elaborately  examined  and  discussed  by  Dr.  MacMunn,  ^ 
found  in  the  tissues  of  many  animals,  both  invertebrate  and  vertebrate. 
Thus  they  have  been  found  in  the  echinodermata,  mollusca,  arthro- 
poda,  and  vermes,  where  they  may  be  detected  in  the  absence  of 
haemoglobin  and  its  derivatives,  which  apparently  they  replace.  With 
regard  to  the  vertebrata,  Dr.  MacMunn  says — "In  vertebrata  the 
search  for  histohsematins  in  the  organs  and  tissues  is  attended  with 
difficulty,  OAving  to  the  presence  of  haemoglobin,  but  fortunately  the 
bands  of  the  histohsematins  can  be  recognized  in  the  tissues  or  organs 

^  MacMunn,  Jour,  of  Physiology,  vol.  vi.  p.  39. 

2  MacMunn  on  Myohaematin  and  the  Histohsematins.  Phil.  Trans,  of  Eoyal 
Society,  part  i.  1886. 


138  THE  CHEMIST IIY  OF  THE  BODY. 

when  squeezed  out  to  a  degree  of  thinness  which  no  longer  allows  the 
bands  of  hiemoglobin  to  be  seen,  and  in  most  cases  the  blood-vessels 
can  be  injected  "vvith  salt  solution  sufficienth"  to  eliminate  the  influence 
of  the  circulating  hjemoglobin."  Dr.  MacMunn  has  detected  them  in  the 
stomach  wall,  liver,  kidneys,  and  intestinal  Avail  of  various  fishes;  in  the 
testes,  liver,  si:)leen,  and  stomach  wall  of  the  frog  and  other  amphibians; 
in  the  liver,  spleen,  Iddney,  and  intestinal  wall  of  various  reptiles;  in  the 
spleen,  pancreas,  liver,  kidney,  and  gizzard  of  the  common  rock  pigeon 
and  other  birds ;  in  the  liver,  spleen,  kidney,  and  stomach  wall  of  the 
hedgehog,  guinea-pig,  rat,  rabbit,  dog,  cat,  pig,  ox,  and  sheep.  He 
also  discovered  a  histohsematin  in  the  thymus  gland  of  a  child  of  ten 
months  old,  and  in  the  spleen,  liver,  and  kidnej'  of  man.  A  haemo- 
chromogen  was  detected  in  the  medullary  portion  of  the  human  supra- 
renal body,  and  a  histohfematin  in  the  cortex.  No  trace  was  discovered 
in  nervous  tissues  in  invertebrates  or  vertebrates.  No  histohfematins 
have  yet  been  isolated,^  as  they  are  probably  united  to  a  proteid,  the 
compound  being  changed  by  the  action  of  the  various  solvents  used. 
Dr.  MacMunn,  however,  has  made  the  important  discovery  that  they 
can  be  reduced  in  the  tissues,  and  that  the  appearance  of  an  absorption 
spectrum  of  bands  indicates  a  reduced  state  of  the  histohsematins,  the 
"  bandless "  specti'um  characterizing  them  in  the  oxidized  condition. 
The  histohfematins  are  allied  to  the  hgemochromogens,  the  spectra  being 
changeable  into  one  like  that  of  hsemochromogen ;  and,  as  "  their 
bands  are  intensified  by  alkalies  and  enfeebled  by  acids,  intensified 
by  reducing  agents  and  enfeebled  by  oxidizing  agents,"  they  are 
capable  of  oxidation  and  reduction,  and  are  therefore  respiratory. 
They  are  concerned  in  the  internal  respiration  of  the  tissues. 
The  position  of  the  bands  is  thus  indicated  by  Dr.  MacMunn — 
(1)  Stomach  tcall  of  cat — blood  free:  '"Ist  band,  A613  to  A593  ;  2nd 
band,  A569  to  A563;  3rd  band,  A556  to  A551.  (2)  Kidney  of  cat:  1st  band, 
A613  to  A596-5;  2nd  band,  A569  to  A563 ;  3rd  band,  A556  to  A550."2 

2.  Myohcematm. — This  is  a  pigment,  of  a  yellowish-red  colour,  also 
discovered  by  Dr.  MacMunn  in  the  muscles  of  certain  beetles  (Hydro- 
jphilus,  Dytiscus),  the  common  fly  (Musca  vomitoria),  and  other  insects ; 
in  spiders,  crustaceans,  molluscs,  fishes,  amphibians,  rei^tiles,  birds  and 
mammals.^  He  has  also  found  it  in  the  heart  and  voluntary  muscles  of 
man.      "Its   bands   are   seen  Avith   great   distinctness  in   the  muscidi 

^  Although  they  can  be  got  into  sohitioii  by  means  of  ether,  see  below, 
Myohjematin. 

-MacMunn,  "Fui'ther  Observations  on  Myoha?matiu  and  the  Histohsmatins, " 
Jour.  ofPhi/sio'.  vol.  viiii  Ko.  2. 

^  MacMiinn,  Phil.  Trans,  op.  cit.  part  i.  18S6. 


THE  PIGMENTS.  139 

papillares  of  the  human  heart."  By  a  process  of  freezing,  combined 
\vith  pressure,  which  apparently  prevents  the  decomposition  of  the 
proteid  compound  in  which  myohaematin  exists,  Dr.  MacMunn^  has 
obtained  "a  few  drops  of  a  reddish-yellow  licjuid,"  which  gives  the 
characteristic  spectrum,  mixed  Avith  the  spectrum  of  oxy-hsemoglobin. 
On  reducing  the  latter  with  ammonium  sulphide,  "  through  the  thin  hazy 
band  of  reduced  haemoglobin,"  the  bands  of  myohaematin  were  apparent. 
The  spectrum  of  myohaematin  from  the  alar  muscle  of  a  meat  fly  is 
shown  in  Plate  I.  11,  and  Dr.  MacMunn  remarks— "The  spectrum  is 
practically  the  same  throughout  the  whole  animal  kingdom."  He  gives 
the  position  of  the  bands  as  follows — "(1)  Heart  of  hare:  1st  band, 
A613  to  A600;  2nd  band,  A569  to  A.563;  3rd  band,  A556  to  A550. 
(2)  Heart  of  rat:  1st  band,  A613  to  A.596-5  ;  2nd  band,  A.569  to  A.563 
3rd  band,  A556  to  A550." 

F. — Luteins  or  Lipockromes. 

In  1849,  Dr.  Thudichum-  described  a  pigment  which  he  obtained 
from  the  corpora  lutea,  from  eggs,  from  butter,  and  from  blood  serum, 
to  which  he  gave  the  name  lutein.  Considerable  doubt  has  been 
thrown  on  the  existence  of  all  of  these  bodies,  but  a  colouring  matter 
gi\dng  absorption  bands  does  exist  in  the  corpora  luteit  and  in  the  yolk 
of  egg.^  A  yellow  colouring  stuff  has  been  extracted  by  ether  from 
the  eyes  of  frogs  after  removal  of  the  retinae.  It  has  two  absoqDtion 
bands  between  F  and  G,  and  it  bleaches  by  sunlight.  It  has  been  called 
lipochrin,  and  is  no  doubt  a  lutein.  The  lutein  pigment  is  held  in 
solution  in  fatty  matter.  The  name  Upochromes  has  been  given  bj- 
Krukenberg  to  all  animal  pigments  soluble  in  certain  fat  solvents  and 
that  give  bands  in  the  blue  and  violet.  These  are  all  luteins.  They  give 
in  the  solid  state  a  blue  or  green  colour  with  strong  nitric  and  sulphioric 
acids,  also  generally  with  iodine  dissolved  in  iodide  of  potassium.  An 
immense  number  of  lipochromes  have  been  found  not  only  among 
animals  but  also  among  plants.  Carotin,  C^gHg^O,  may  be  taken  as  a 
typical  Hpochrome.     None  so  far  has  been  found  to  contain  nitrogen. 

^  MacMunn  has  obtained  myohiematin  in  solution  from  the  pectoral  muscles  of 
pigeons  by  covering  the  blood-free  muscles  (finely  diAided)  with  ether  for  some 
days,  when  a  red  juice  exudes,  which  shows  the  bands  of  modified  myohccmatin. 
J(mr.  of  Physiol,  vol.  viii.  No.  2,  18S7. 

-  Thudichum,  Proc.  Roy.  Soc.  xvii.  253.  The  yellow  colouring  matter  was  first 
separated  from  ovary  of  cow  by  Piccolo  and  Lieben  and  called  huemolutein.  An 
ethereal  extract  of  corpora  lutea  boiled  with  potash  has  excess  of  water  added, 
when  small  shinmg  dichroic  crystals  are  deposited. 

^MacMunn  on  "Animal  Chromatology, "  Proceed,  of  Birmingham  Philosoph. 
Society,  vol.  iii.  ISS3. 


140 


THE  CHEMISTRY  OF  THE  BODY. 


G. — Chromophanes. 

These  are  colouring  matters  that  have  been  separated  hy  Kuhne  from 
the  cones  of  the  retina.  Three  such  bodies  have  been  isolated  and  their 
spectra  examined.'  "A  large  number  of  eyes  (50  to  .300)  of  doves  or 
hens  are  bisected  so  as  to  cut  off  the  anterior  segments ;  the  vitreous 
humour  being  removed,  the  posterior  segments  of  the  eyes  are  placed  at 
once  in  absolute  alcohol :  as  soon  as  possilile  the  alcohol  is  poured  aAvay 
and  the  eyes  are  thoroughly  exhausted  with  ether.  On  evaporating  the 
ether,  a  fier3'-red  fat  is  obtained  wliieh  is  dissolved  in  hot  alcohol  and 
saponified  by  the  action  of  caustic  soda,  Avatcr  being  used  to  replace  the 
alcohol  as  it  evaporates.  The  hard  soap  -which  separates  from  the 
mother  liquor  is  well  dried  and  treated  successively  with  petroleum 
ether,  then  \n.t\i  ether,  and  lastly  Avith  benzol,  which  dissolve  in  order — 
clilorophane,  xanUiophane,  and  rhodophane."  The  probable  function  of  these 
colouring  matters  in  connection  with  the  sense  of  vision  \n[\  be  dis- 
cussed fully  in  treating  of  that  sense.  All  that  is  here  necessary  is  to 
describe  shortly  the  spectra  of  these  pigments. 

a.  Clilorophane  is  a  greenish-yellow  j^igment  and  gives  the  absorption 
bands  seen  in  Fisc.  56. 


Spectrum. 


C     D 


.^ 


,4« 


Fic.  56. — Spectnim  of  Chlorophane — A,  dissolved  in 
ether  oi-  in  petroleum  ether ;  B,  dissolved  in  bi- 
srjphide  of  carbon. 

1).  Xantliophane  is  slightly  soluble  in  petroleum  ether,  readily  soluble 
in  alcohol,  ether,  and  carbon  disulphide,  and  gives  the  spectrum  seen  in 
Fig.  57. 


Spectrum. 


a  5 


C      Z> 


E& 


E 


.^^ 


Fig.  57. — Spectrum  of  Xautliophnne — A,  dissolved 
in  ether  ;  B,  dissolved  in  bisulphide  of  carbon. 

'  Gamgee's  Physiological  Chemistry,  vol.  i.  p.  460. 


THE  PIGMENTS. 


141 


c.  Ehodophane  is  insoluble  in  petroleum  ether  or  carbon  disulphide,  is 
soluble  in  oil  of  turpentine,  in  alcobol  acidified  with  acetic  acid,  and  in 
benzol,  and  it  shows  the  spectrum  given  in  Fig.  58. 


Spectrum. 


«  IB 


m 


Fig.  58. — Spectrum  of  Rhodophane — A,  dissolved  in 
benzol ;  B,  dissolved  in  oil  of  turpentine. 

d.  Ehodopsin  or  visual  purple  is  a  colouring  matter  associated  with 
the  rods  of  the  retina,  and  sensitive  to  light.  Kiihne  discovered  that  it 
is  soluble  in  "  crystallized  bile  "  thus  prepared — 

"  Colourless  crystallized  bile  is  obtained  by  evaporating  ox-bile  to  dryness  in  the 
water  bath,  after  mixing  it  thoroughly  with  much  animal  charcoal.  The  perfectly 
dry  residue  is  treated  with  absolute  alcohol,  and  a  large  excess  of  ether  is  added  to 
the  filtered  solution  ;  by  this  means  the  salts  of  the  bile  acids  are  precipitated  and 
ultimately  acquire  a  crystalline  structure.  The  precipitate,  which  consists  of 
sodium  glycocholate  and  taurocholate  is  termed  '  crystallized  bile.'  "  ^ 

As  this  substance  is  destroyed  by  the  action  of  actinic  light,  care 
must  be  taken  to  open  the  eyes  of  frogs  in  a  chamber  lit  by  a  sodium 
flame,  and  the  retinae  are  moistened  with  about  1  c.c.  of  a  2  per  cent, 
solution  of  the  bile  salts,  and  gently  shaken  for  about  one  hour.  A 
reddish-purple  fluid  is  thus  obtained  which  is  a  solution  of  rhodopsin. 
Light  causes  it  to  pass  from  purple,  "  through  red  and  orange,  to  yellow, 
before  becoming  colourless."  Thus  "visual  purple"  is  converted  into 
"visual  yellow"  and  the  latter  then  fades  away.  The  spectra  of  the 
two  conditions  are  shown  in  Fia;.  59. 


A. 

a. 

:              K 

Spectrum. 

3 

C 

D 

f 

h 

F 

^, 

B. 

■ 

1 

Fig.  59. — Spectriim  of  Rhodopsin— A,  unaltered  by- 
light,  "  visual  purple  ";  B,  altered  by  light,  "visual 
yellow." 

^  Gamgee's  Physiological  Chemistry,  vol.  i.  p.  464. 


142  THE  CHEMISTRY  OF  THE  BODY, 


H. — Black  Pigment. 

A  black  |)it;iiioiit  named  Melanin  occurs  in  the  hexagonal  epithelial 
colls  forming  the  external  layer  of  the  retina  (Fig. 
60)  in  the  connective  tissue  cells  of  the  choroid 
itself,  in  the  deeper  layer  of  the  epidermis  of  the 
skin,  constituting  the  rete  Malpighi,  and  it  is  often 
I.— PigmTntcfiis.  fouud  in  various  kinds  of  timaours.  It  also  occiu's 
in  the  skin  of  fishes,  amphibians,  and  reptiles,  and  in  the  feathers  of 
birds.  In  amphibians,  such  as  the  frog,  it  is  abundant  even  in  the  deep 
tissues  and  organs  of  the  body.  The  ink  of  the  cuttle-fish  is  of  the 
same  nature;  but  there  is  no  doubt  that  quite  different  colouring 
matters  have  been  included  under  the  name  melanin,  Avhich  only 
possess  one  attribute  in  common,  \\z.,  blackness.  Some  of  these  pigments 
are  non-nitrogenous,  e.g.  from  birds  and  Seioia  (cuttle-fish).  It  is  insoluble 
in  water,  acids,  alcohol,  and  ether.  It  is  imperfectly  dissolved  in  boil- 
ing caustic  potash,  a  brown  fluid  being  formed,  thus  distinguishing  it 
from  the  particles  of  carbon  sometimes  found  in  lung  tissue,  which  are 
quite  insoluble  in  boiling  caustic  potash.  The  percentage  composition 
varies  from  C,  51-7  to  58-3;  H,  4-02  to  5-09;  N,  7-1  to,  13-8;  and  0,  22-03 
to  35-44.1  The  pigment  of  the  choroid  is  said  to  contain  a  small 
amount  of  iron. 

I.— Other  Animal  Pigments. 

To  attempt  to  give  the  characters  of  the  numerous  pigments  existing  in 
animals,  more  especially  among  the  invertebrata,  that  have  been  described 
by  Moseley,  Ray  Lankester,  Krukenberg,  MacMunn,  and  others  in  recent 
years,  is  quite  beyond  the  aim  of  this  work.  Only  a  few  are  alluded  to, 
specially  \n.\h.  the  view  of  pointing  out  the  wide  range  of  many  of  these 
pigments,  and  the  remarkable  resemblance  they  bear  to  some  of  the 
pigments  already  described  as  relating  to  man  and  the  higher  animals. 
This  branch  of  inquiry  is  still  in  its  infancy,  but  enough  has  been  done 
to  show  the  resemblance  between  plant  and  animal  pigments  and  the 
fact  that  not  a  few  of  them  are  concerned  in  respiratory  processes.  The 
follo-\^4ng  are  a  few  of  the  more  imjDortant.^ 

1.  Chlai-ophyU  occurs  in  many  of  the  lower  invertebrates  (Spongilla, 
Hydra,  Paramecium),  and  Professor  Ray  Lankester  has  sho^\^l  that  the 

^Gamgee,  Physiological  Chemistry,  vol.  i.  p.  304. 

-The  inquirer  wishing  to  study  these  pigments  may  refer  to  MacMunn's  papers 
already  frequently  referred  to,  which  are  not  only  critical  and  full  of  the  results 
of  original  inquiry,  but  also  give  many  references  to  the  literature  of  the  subject. 


THE  PIGMENTS.  I43 

corpuscles  are  part  of  the  animal  itself  and  not  unicellular  algae  leading 
an  independent  existence,  as  Brandt  supposed.^  It  has  also  been  found 
in  the  blood  of  caterpillars  ^  and  in  the  elytrse  of  cantharides  beetles.-^ 
Dr.  MacMunn  has  found  in  many  animals  (more  especially  in  alcoholic 
extracts  of  the  "  liver  and  other  appendages  of  the  intestine  answering 
to  it"),  a  substance  having  a  spectrum  similar  to  that  of  the  chlorophyll 
of  plants,  to  which  he  gives  the  name  entero-cMaivphyllA  He  has  also 
recently  found  chlorophyll  in  several  salt  water  sponges.-^ 

2.  Hcemocyanin  is  a  blue  isigment  found  in  the  blood  of  many  inverte- 
brates. The  blood  of  many  molluscs  and  arthropods  becomes  bluish  in 
colour  after  exposure  to  the  air  {Helix,  Unio,  Limulus,  Odojms,  Sepia., 
Scorpio,  Cancer,  Homarus,  Portunus,  Maja,  Sqidlla,  etc.).  MacMunn  found 
no  absorption  bands  in  that  of  Helix  pomatia.  Helix  aspera,  Paludimt 
vivipara,  Lymnmis  stagnalis,  Homarus  vulgaris,  Cancer  pagiirus,  Carcimis 
mcenas,  and  Astacus  flimatcdis.^ 

3.  Chlorocruorin  is  a  green  pigment  discovered  by  Professor  Ray 
Lankester  in  the  blood  of  Sahella  ventilabrum  and  Siplionostoina,~  which  is 
capable  of  being  oxidized  and  reduced  by  ammonium  sulphide  like 
haemoglobin.  MacMunn  has  figured  the  spectrum  of  the  blood  of 
Sahella  and  of  Serpida  contortuplkata  in  the  paper  referred  to,^  and  shown 
its  resemblance  in  some  respects  to  that  of  hsemochromogen. 

4.  Echinoclirome  is  a  brown  pigment  found  in  the  perivisceral 
cavities  of  Echinus  (Schafer,  P.  Geddes,  and  MacMunn),  and  also  in 
Strongylocentrotus  livichis  by  MacMunn,  who  first  described  its  spectrum. 
When  exposed  to  the  air  it  becomes  deeper  in  colour.  Dr.  MacMunn 
remarks  with  regard  to  the  spectra  figured  in  the  paper — "  A  compari- 
son of  these  spectra  shows  hoAv  remarkably  unstable  echinochrome  is. 
It  is  on  this  instability  that  its  usefulness  as  a  respiratory  substance 
depends." 

^  Eay  Lankester  on  the  Chlorophyll  Corpuscles  and  Amyloid  Deposits  of  Spongilla 
and  Hydra — Quart.  Jour,  of  Micros.  Science,  vol.  xxii.  KS.  See  also  MacMunn 
on  the  Spectroscope  in  Biology — Proceed,  of  Birmiwjham  PhiloaoyMcal  Society,  vol. 
V.  part  ],  and  Quart.  Jour.  Micros.  Science,  vol.  xxvii.  p.  573  et  seq. 

2  Poulton,  The  essential  nature  of  the  colouring  of  Phytophagoiis  Larvse — Proc. 
Boy.  Soc.  1885. 

3  Pocklington,  Phar.  Jour.  Trans,  vol.  iii.  ;  MacMunn,  By^it.  Ass.  Report,  1883. 
*  MacMunn,  Further  observations  on  Enterochlorophyll  and  Allied  Pigments — 

Phil.    Trans.   Royal  Society,  part  1,    1886.     See  also  MacMunn's  Notes  on  the 
Chromatology  oi  Anthea  cerevs — Quart.  Jour,  of  Micros.  Science,  March,  1887. 
5  MacMunn,  Proc.  Physiol.  Soc.  March,  1887. 

^MacMunn,  Chromatology  of  Blood  of  some  Invertebrates — Quart.  Jour,  of 
Micros.  Science,  1885. 

'^  Raj  Lankester,  Jour,  of  A7iat.  and  Physiol.   1868. 


144  THE  CHEMISTRY  OF  THE  BODY. 

5.  Fentacrinin,  a  pigment  discovered  by  Professor  H.  N.  Moseleyi  in 
species  of  Pentacnnus  dredged  1)}^  H.M.S.  "  Challenger."  It  exists 
either  as  a  purple  or  a  red  pigment,  and  gives  a  spectrum  of  three 
bands,  "  one  intensely  black  covers  D,  the  second  is  between  D  and  E, 
and  the  third,  a  broad  dim  one,  stretches  from  h  to  F."  Its  spectra 
have  been  mapped  and  measured  by  MacMunn  {Froc.  Fhil.  Soc.  Birming. 
op.  cit.),  and  he  remarks — "  It  may  be  concluded,  however,  that  Mose- 
ley's  purple  pentacrinin  does  bear  a  most  remarkable  resemblance  to 
plant  pigments.  It  also  bears  a  resemblance  to  honelle'm,  the  colouring 
matter  of  Bonella  liridis,  which  had  long  been  taken  to  be  a  chlorophyll, 
and  which  Professor  Lankester  thinks  may  also  be  present  in 
Ch(etopterus." 

6.  Adiniohcematin  is  a  colouring  matter  found  in  Actinia  mesembryan- 
themum  by  ]\IacMunn,  which  can  be  changed  into  hsemochromogen  and 
haematoporphyrin.  It  is  not  actiniochrome,  a  pigment  A^dely  distributed 
in  actinia?,  chiefly  in  the  tentacles.  In  Sagartia  parasitim,  a  special 
pigment  is  found  not  identical  Avith  either  actiniohaematin  or  actinio- 
chrome, and  in  Anthea  cereus,  JBimodes  halii,  and  Sagartia  hellis,  a  mix- 
ture of  plant-like  pigments  is  met  with  containing  chlorofucin  (an  algal 
pigment),  and  derived  from  the  "yellow  cells"  in  the  tentacles.- 

7.  Turacin  is  a  pigment  obtained  from  the  feathers  of  the  Cape  lory, 
which  is  said  to  give  a  spectrvim  like  that  of  blood.     (Church.) 

8.  Tetronerijthrin  is  a  pigment  found  by  Hoppe-Seyler  in  the  rose- 
coloured  rings  round  the  eyes  of  certain  birds.  Merejkowski^  has 
found  it  in  104  species  of  invertebrates  and  fishes.  This  body  is  of 
great  interest  inasmuch  as  it  is  said  to  perform  the  fimction  of  haemo- 
globin as  a  carrier  of  oxygen  to  the  tissues.  In  many  invertebrates  it 
takes  the  place  of  haemoglobin,  and  this  no  doubt  accounts  for  its  wide 
distribution. 

9.  Crustaceoruhin^  is  the  name  given  by  Moseley  to  a  pigment  he 
found  in  some  deep-sea  decapod  Crustacea. 

10.  Cochineal,  from  the  insect  Kermes  cacti,  and  Lac-chje,  from  Coccus 
laccce,  give  no  characteristic  absorption  spectrum.  Carminic  acid, 
from  carmine,  gives  a  spectrum  somewhat  resembling  that  of  haemo- 
globin. 

11.  Aphidein  is  a  pig-ment  obtained  by  Sorby  from  Aphides.  It  gives 
an  absorption  spectrum,  and  it  appears  to  be  a  true  respiratory  pig- 

1  Moseley,  Quart.  Jmir.  of  Micros.  Science,  1877. 

-  MacMunn,  Xotes  on  the  Chromatology  of  Anthea  cereus — Quar.  Jour,  of 
Micros.  Science,  vol.  xxvii.  IST.S.,  p.  573-590. 

^It  would  appear  that  under  the  name  "  tetronerythrin  "  several  lipochromes  of 
a  reddish  colour  have  been  included. 

■*  Probably  identical  with  tetronerythrin. 


EXPLANATION  OF  THE  PLATE  OF  SPECTRA. 

(FRONTISPIECE.) 


3ctruin  of  diffused  daylight  with  some  of  the  principal  lines  of  Fraunhofer, 

sctrum  of  oxy-hcemoglohin  in  a  moderately  dilute  solution,  p.  121. 

3ctrum  of  reduced  hcemoglohin,  p.  122. 

sctrum  of  methcemoglobin,  got  by  adding  a  solution  of  potassium  permanganate  to 

)n  of  sheep's  blood  in  water,  p.  125. 

ectrum  of  alkaline  methcemoglobin,  got  by  treating  the  last  solution  with  a  little 

a,  p.  126. 

ectrum  of  acid  hcematin,  got  by  treating  blood  with  acetic  acid  and  agitating  with 

;he  acid  hsematin  got  by  treating  blood  with  rectified  spirit  containing  sulphuric 

embles  this  but  wants  the  full  band  at  D,  j).  127. 

ectrum  of  alkaline  hcematin,  got  by  treating  blood  with  rectified  spirit  and  caustic 

Chis  differs  from  the  alkaline  hsematin  produced  by  the  action  of  rectified  spirit 

;ionia,  as  the  latter  does  not  give  the  band  at  D,  but  a  dark  hazy  band  in  the  green, 

ectrum  of  reduced  hcematin  or  hcemochromogen,  got  by  adding  sulphide  of  am- 
.  to  the  solution  of  alkaline  ha;matin.  The  latter  should  be  prepared  by  the  action 
onia  and  rectified  spirit,  as  in  this  case  the  hsemochromogen  bands  are  better 

p.  125. 
ectrum  of  acid  hcematoporphprin,  prepared  as  follows :— Defibrinated  blood  is 
with  rectified  spirit  acidulated  with  sulphuric  acid,  filtered,  diluted  with  water, 
.  in  a  tap-funnel  with  chloroform,  the  chloroform  separated  off  and  evaporated  to 
,  the  brown  residue  divided  in  strong  sulphuric  acid  and  filtered  through  asbestos, 
pg  a  little  rectified  spirit  this  spectrum  can  be  seen.  By  treating  blood  or  hsemo- 
lirectly  with  strong  sulphuric  acid  and  filtering  through  asbestos  a  similar  spec- 
j,y  be  observed,  but  it  is  better  to  proceed  as  above,  as  then  the  influence  of  the 
constituent  is  avoided,  p.  127. 

Dectrum  of  cdkaline  hcematoporpltyrin,  got  by  poiuing  the  sulphuric  acid  solution 
ned  under  9)  into  water,  adding  ammonia,  removing  by  filtering  brown  flocks,  which 
b,  dissolving  the  precipitate  in  rectified  spirit  and  ammonia,  p.  127. 
^ectrum  of  myoluematin,  from  alar  muscle  of  a  meat  fly.     The  spectrum  is  practi- 
ie  same  throughout  the  whole  animal  kingdom,  p.  139. 

jpectrum  of  cholohcematin  from  sheep's  bile.  The  bile  is,  after  addition  of  absolute 
land  acetic  acid  and  filtering,  agitated  in  a  tap -funnel  with  chloroform,  which, 
jparation,  shows  this  spectrum.  On  letting  the  chloroform  stand  for  a  day  or 
\bilin  band  also  generally  becomes  visible,  p.  132. 

pectrum  of  a  moderately  dilute  chloroform  solution  of  bilirubin,  which  shows 
Sorption  of  the  violet  end  of  the  spectrum,  no  bands,  p.  130. 

pectrum  of  urobilin  from  normal  urine  thus  prepared  : — The  urine  is  precipitated 
^utral  and  basic  lead  acetate,  the  precipitate  separated  by  filtering,  decomposed 
;fied  spirit  containing  sulphuric  acid,  this  extract  filtered,  diluted  with  water  and 
I  in  a  tap-funnel  with  chloroform,  the  chloroform  separated  off,  filtered, 
,ted,  and  the  brownish  residue  redissolved  in  rectified  spirit.  Febrile  urobilin 
fom  this  in  the  greater  shading  and  breadth  of  band  and  in  other  slight  parti- 

so  does  stercobilin,  p.  134. 

'he  same  solution  with  ammonia  and  zinc  chloride  (filtered),  p.  135. 
pectrum  of  indigo-blue,  etc.,  from  normal  urine.  The  urine  is  boiled  with  about 
af  its  bulk  of  hydrochloric  acid,  cooled  and  agitated  with  chloroform.  It  then  shows 
sctrum,  and  also,  although  not  here  shown,  a  band  at  F  due  to  urobilin.  The  band 
D  is  due  probably  only  to  the  blue  constituent,  indigo-blue,  while  that  after  D  is 
y  due  to  the  reddish  constituent,  for  this  reason  that  the  bluer  the  solution  the 
is  the  band  before  D,  while  the  more  it  approaches  violet  the  darker  is  the  band 
This  test  for  the  presence  of  indican  will  detect  it,  when  Jaffa's  hypochlorite 
um  test  fails  ;  and  normal  urine  can  generally  be  made  to  show  the  presence  of 

by  its  means,  p.  136. 

e  spectra  were  mapped  by  means  of  a  Sorby's  microspectroscope.  In  the  chemical 
scope  the  bands  are  more  hazy  and  some  of  the  faint  ones  difficult  to  see.  The 
of  light  was  an  Argand  gas  burner. 


EXPLANATION  OF  THE  PLATE  OF  SPECTRA. 

(FRONTISPIECE.) 


1.  Spectrum  of  diffused  daylight  -with  some  of  tlie  principal  lines  of  Fraunhofer^ 
p.  112. 

2.  Spectrum  of  oxy-hmmogloMn  in  a  moderately  dilute  solution,  i>.  121. 
'd.  Spectrum  of  reduced  hcemoglobin,  p.  122. 

4.  Spectrum  of  methcemoplohint  got  by  adding  a  solution  of  potassium  permanganate  to 
a  solution  of  sheep's  blood  in  water,  p.  125. 

5.  Spectrum  of  alkaline  meth(emogJohin,  got  by  treating  the  last  solution  with  a  little 
ammonia,  p.  126. 

6.  Spectrum  of  acid  hmmatin,  got  by  treating  blood  with  acetic  acid  and  agitating  with 
ether ;  the  acid  heematin  got  by  treating  blood  with  rectified  spirit  containing  sulphuric 
acid  resembles  this  but  wants  the  full  band  at  D,  j).  127. 

7.  Spectrum  of  alkaline  hcematin,  got  by  treating  blood  with  rectified  spirit  and  caustic 
soda.  This  differs  from  the  alkaline  hsematin  produced  by  the  action  of  rectified  spirit 
and  ammonia,  as  the  latter  does  not  give  the  band  at  D,  but  a  dark  hazy  band  in  the  green, 
p.  127. 

8.  Spectrum  of  reduced  hcematin  or  hmmochromogen,  got  by  adding  sulphide  of  am- 
monium to  the  solution  of  alkaline  hiematin.  The  latter  should  be  prepared  by  the  action 
of  ammonia  and  rectified  spirit,  as  in  this  case  the  hremochromogen  bands  are  better 
marked,  p.  125. 

9.  Spectrum  of  acid  hcematoporphyrin,  prepared  as  follows  : — Defibrinated  blood  is 
treated  with  rectified  spirit  acidulated  with  sulphuric  acid,  filtered,  diluted  with  water, 
agitated  in  a  tap-funnel  with  chloroform,  the  chloroform  separated  off  and  evaporated  to 
dryness,  the  brown  residue  divided  in  strong  sulphuric  acid  and  filtered  through  asbestos. 
On  adding  a  little  rectified  spirit  this  spectrum  can  be  seen.  By  treating  blood  or  h£erao- 
globin  directly  with  strong  sulphuric  acid  and  filtering  through  asbestos  a  similar  spec- 
trum may  be  observed,  but  it  is  better  to  proceed  as  above,  as  then  the  influence  of  the 
proteid  constituent  is  avoided,  p.  127. 

10.  Spectrum  of  alkaline  ha^matoporphi/rin,  got  by  poiu-ing  the  sulphuric  acid  solution 
(mentioned  under  9)  into  water,  adding  ammonia,  removing  by  filtering  brown  flocks,  which 
separate,  dissolving  the  precipitate  in  rectified  spirit  and  ammonia,  p.  127. 

11.  Spectrum  of  myohcematin ,  from  alar  muscle  of  a  meat  fly.  The  spectrum  is  practi- 
cally the  same  throughout  the  whole  animal  kingdom,  p.  139. 

12.  Spectrum  of  choloJuematin  from  sheep's  bile.  The  bile  is,  after  addition  of  absolute 
alcohol  and  acetic  acid  and  filtering,  agitated  in  a  tap-funnel  with  chloroform,  which, 
after  separation,  shows  this  spectrum.  On  letting  the  chloroform  stand  for  a  day  or 
so  a  urobilin  band  also  generally  becomes  visible,  p.  132. 

13.  Spectrum  of  a  moderately  dilute  chloroform  solution  of  bilirubin,  which  shows 
only  absorption  of  the  violet  end  of  the  spectrum,  no  bauds,  p.  130. 

14.  Spectrum  of  urobilin  from  normal  urine  thus  prepared  : — The  urine  is  precipitated 
with  neutral  and  basic  lead  acetate,  the  preciintate  separated  by  filtering,  decomposed 
by  rectified  spirit  containing  sulphuric  acid,  this  extract  filtered,  diluted  with  water  and 
agitated  in  a  tap-funnel  with  chloroform,  the  chloroform  separated  off,  filtered, 
evaporated,  and  the  brownish  residue  redissolved  in  rectified  spirit.  Febrile  urobilin 
differs  from  this  in  the  greater  shading  and  breadth  of  band  and  in  other  slight  parti- 
culars; BO  does  stercobilin,  p.  134. 

15.  The  same  solution  with  ammonia  and  zinc  chloride  (filtered),  p.  135. 

16.  Spectrum  of  indigo-blue,  etc.,  from  normal  urine.  The  urine  is  boiled  with  about 
athird  of  its  bulk  of  hydrochloric  acid,  cooled  and  agitated  with  chloroform.  It  then  shows 
this  spectrum,  and  also,  although  not  here  shown,  a  band  at  f  due  to  urobilin.  The  band 
before  d  is  due  probably  only  to  the  blue  constituent,  indigo-blue,  while  that  after  D  is 
probably  due  to  the  reddish  constituent,  for  this  reason  that  the  bluer  the  solution  the 
deeper  is  the  band  before  d,  while  the  more  it  approaches  violet  the  darker  is  the  band 
after  d.  This  test  for  the  presence  of  indican  will  detect  it,  when  Jaffa's  hypochlorite 
of  calcium  test  fails  ;  and  normal  urine  can  generally  be  made  to  show  the  presence  of 
indican  by  its  means,  p.  136. 

These  spectra  were  mapped  by  means  of  a  Sorby's  microspectroscope.  In  the  chemical 
spectroscope  the  bands  are  more  hazy  and  some  of  the  faint  ones  difficult  to  see.  The 
source  of  light  was  an  Argand  gas  burner. 


THE  FIGMENTS.  I45 

ment.     Sorby  shows  that  aphidein  is  related  to  cochineal  on  the  one 
hand  and  to  haemoglobin  on  the  other. 

12.  Aplysiopurpurin  is  a  purple  colouring  matter  obtained  by  Moseley 
from  the  Doris  (nudibranch).     It  also  exists  in  Aplysia,  the  sea-hare. 

13.  Tyrian  jpmjjU  is  the  dye  obtained  from  species  of  Purpura  and 
Murex,  and  is  a  secretion  of  a  layer  of  epithelium,  "  which  is  placed 
between  the  gills  and  the  hind  gut  in  the  mantle  cavity." 

Conclusions  Eegarding  the  Pigments. 

The  previous  discussion  of  the  nature  and  properties  of  the  pigments 
enables  us  to  appreciate  their  physiological  significance  and  to  understand 
in  some  measure  the  part  they  play  in  the  animal  body.  In  most,  if  not 
in  all,  animals  there  is  one  chief  pigment  such  as  the  haemoglobin  in  the 
blood  of  the  higher  groups,  and  the  entero-chlorophyll,  haemocyanin, 
chloro-cruorin,  echinochrome,  or  tetronerythrin^  of  many  of  the  lower. 
This  chief  pigment  is  mainly  if  not  wholly  concerned  in  respiration,  by 
its  property  of  combining  readily  with  a  certain  amount  of  oxygen  and 
of  giving  this  up  to  a  reducing  agent.  Thus  it  receives  oxygen  from  the 
air  or  from  the  air  dissolved  in  the  water  in  which  the  creature  lives, 
and  it  conveys  this  oxygen  to  the  living  tissues.  These  tissues  practi- 
cally reduce  it,  and  it  returns  to  its  non-oxygenated  condition.  In  this 
process,  however,  it  is  not  a  stable  substance.  It  undergoes  decomposi- 
tion, becoming  modified  into  histohaematins  that  permeate  the  tissues,, 
probably  entering  into  their  very  substance  and  still  exercising  a  respir- 
atory function.  May  it  not  be  possible  that  these  histohaematins  act 
intermediately  as  regards  the  haemoglobin  (or  its  representative)  of  the 
blood  and  the  oxygen-seeking  living  tissue?  Again,  the  haemoglobin 
may  be  resolved  in  the  liver  cells,  or  in  the  intestinal  canal,  or  in  the 
kidneys,  and  probably  in  other  organs,  into  simpler  bodies  which  then 
appear  as  the  pigments  of  the  various  excretions,  waste-products,  in  short, 
formed  in  the  chemical  operations  of  the  body.  Such  are  probably  the 
pigments  of  the  bile,  of  the  urine,  and  of  the  faeces,  bodies  of  no  physio- 
logical value,  and  voided  as  useless,  at  all  events  in  the  higher  animals. 
In  some  of  the  lower  animals,  however,  such  waste-pigments  may  not  be 
useless,  but  if  innocuous  they  may  be  stored  up  in  the  epidermal  tissues, 
thus  staining  the  covering  of  the  body  so  as  to  suit  the  habits  of  the 
animal,  or  perhaps  adorning  it  with  beautiful  colours  that  serve  some 
useful  purpose  in  the  circumstances  of  its  life.  Lastly,  certain  pigments 
have  a  more  specialized  function.  Such  are  the  pigments  in  the  eye-spots 
of  many  of  the  humbler  forms,  and  the  pigments  of  the  rods  and  cones  of 

^  With  regard  to  the  latter,  it  has  never  yet  been  shown  that  it  is  affected  by 
reducing  agents. 

I.  K 


146  THE  CHEMIST R  Y  OF  THE  BODY, 

the  retina.  These  arc  sensitive  to  light,  and  by  the  chemical  changes  occiu'- 
ring  in  them  under  the  influence  of  light  the  ends  of  the  optic  nerve  fibres 
may  possibly  be  stimulated.  The  recent  researches  into  the  nattu-e  of  pig- 
ments are  of  profomid  interest  as  giving  us  an  insight  into  some  obscm^e 
processes,  and  there  is  little  doubt  that  after  the  comparative  study  of 
pigments  has  progressed  much  farther  than  it  has  yet  done  even  more 
important  generalizations  may  be  possible  than  those  I  have  ventured  to 
make.  Nor  is  the  subject  devoid  of  practical  importance.  The  physician 
by  studying  the  amount  and  nature  of  the  iu"inary  pigments,  for  instance, 
may  obtain  valual^le  information  as  to  the  metabolism  occurring  in  the 
liver  and  the  changes  happening  in  the  bowel,  and  it  is  likely  that  a. 
more  careful  study  of  the  pigments  in  some  pathological  conditions,  such 
as  Addison's  disease,  "oith  the  peculiar  bronzing  of  the  skin,  may  throw 
light  on  the  nature  of  these  obscure  affections.^ 

Chap.  X.— THE  NON-NITROGENOUS  MATTERS. 

These  include  the  alcohols,  the  fats,  the  carbo-hydrates,  and  certain 
acids  belonging  to  the  acetic  acid,  the  giy collie  acid,  the  oxalic  acid,  and 
the  oleic  acid  series  of  non-nitrogenous  organic  acids. 

I.    The  Alcohols. 

1.  Ethylic  Alcohol,  C^Hj .  HO,  common  alcohol,  is  said  by  Bechanqj 
and  Eajewski  to  be  formed  in  small  quantities  in  the  body,  so  that  it  may 
be  detected  in  the  urine  even  in  the  absence  from  the  food  and  drink  of 
all  fermented  liquors.  In  these  circumstances  it  must  be  formed  by  an 
alcoholic  fermentation  in  the  body,  either  in  the  intestinal  canal,  or  in 
the  tissues,  most  probably  in  the  former. 

2.  Cholesterin,  or  Cholesteric  Alcohol,  C.,^.H^O  .  HO,  a  crystalline  sub- 
stance in  the  bile,  and  forming  the  chief  constituent  of  gall  stones,  is 
regarded  by  chemists  as  an  alcohol  belonging  to  the  series  C„Ho^_80. 
It  was  first  obtained  by  Conradi,  so  long  ago  as  1775,  from  gall  stones. 
It  exists  in  the  bile,  and  it  has  been  obtained  from  blood,  urine,  nervous 
matter,  yolk  of  egg,  seminal  fluid,  red  blood  corpuscles,  white  blood 
corpuscles,  milk,  the  spleen,  the  contents  of  the  intestines,  the  meconium, 
the  faeces,  tubercular  and  cancerous  deposits,  cataracts  of  the  eye,  and 
atheromatous  blood  vessels.  It  has  also  been  foiuid  in  peas,  fixed  oils, 
fat  of  Avheat,  glutin,  fat  of  rye,  barley,  maize  seeds,  young  shoots  of  roses, 
and  in  yeast.     To  obtain  it  pure,  pulverize  biliary  calculi,  extract  \nth 

^  On  this  subject  see  Dr.  ilacMunn's  suggestive  paper  in  the  British  Medical 
Journal,  Feb.  4th,  1888,  entitled,  "  On  Addison's  Disease  and  the  Function  of  the 
Suprarenal  Bodies. " 


THE  NON-NITROGENOUS  MATTERS.  147 

iDoiling  ether,  distil  off  the  ether,  dissolve  the  residue  in  alcohol,  and 
allow  the  solution  to  cool.  The  crystalline  mass  in  the  solution  is  heated 
for  some  time  with  alcohol  containing  a  little  caustic  potash,  and  on 
cooling,  a  crop  of  crystals  is  obtained. 
These  are  washed  with  alcohol,  and  if  it  is 
desired  to  get  them  prue,  they  may  be  re- 
dissolved  in  and  recrystallized  from  ether. 
The  crystals  are  odourless  and  tasteless. 
They  then  appear  as  rhombic  plates,  often 
with  one  obtuse  angle  awanting  (Fig.  61). 
Cholesterin  is  insoluble  in  water,  in  alkalies 
and  dilute  acids ;  slightly  soluble  in  cold, 
but  very  soluble  in  hot  alcohol,  and  in  ^ig.  (3i.-crystaisofchoiesterin. 
ether,  acetic  acid,  glycerine,  benzol,  petroleum,  chloroform,  and  solutions 
of  the  bile  acids.  Anhydrous  cholesterin  fuses  at  145°  C,  and  solidifies 
at  137°  C.  Its  specific  gravity  is  1-046.  Solutions  of  cholesterin  with 
polarized  light  give  [aju  =  -  31°'6.  Hot  nitric  acid  oxidizes  it  so  as  to 
form  cholesteric  acid,  a,  CgH^QOg,  a  substance  also  produced  by  the  oxid- 
ation of  the  bile  acids.  (Witthaus.)  By  oxidation  with  potassium 
permanganate,  three  acids  may  be  obtained :  cholesteric,  /3,  C26H42O4 ; 
oxy cholesteric,  ^i^io^-^',  and  dioxy cholesteric,  C.^gH^gOg.  (Latschinofi".) 
There  are  two  good  tests  for  cholesterin  :  {a)  If  the  substance  is  bruised 
with  a  few  drops  of  sulphuric  acid,  and  a  drop  or  two  of  chloroform  then 
added,  a  blue-red  or  violet  colour  is  produced,  which  changes  to  green  on 
exposure  to  air ;  and  ih)  when  a  mixture  of  two  volumes  of  sulphuric  acid 
Avith  one  volume  of  ferric  chloride  is  evaporated  upon  cholesterin  a  violet 
colour  appears.  When  sulphuric  acid  is  added  to  a  solution  of 
cholesterin  in  chloroform  the  upper  fluid  becomes  blood-red  or  purple 
red  and  the  under  liquid  has  a  green  fluorescence.  (Salkowski.)'^  A 
substance,  isomeric  with  cholesterin  (isocholesterin),  has  been  obtained  by 
E.  Schulze  from  sheep's  wool. 

The  mode  of  origin  of  cholesterin  in  the  body  has  not  been  clearly 
made  out.  Whether  it  is  formed  in  the  tissues  generally,  or  in  the  blood, 
or  in  the  liver,  is  not  known,  nor  has  it  been  determined  conclusively 
that  it  is  derived  from  the  decomposition  of  albuminous  or  even  of 
nervous  matter.  It  is  also  doubtful  if  we  can  regard  it  as  a  waste- 
substance  of  no  use  in  the  body,  as  its  presence  in  the  blood  corpuscles, 
in  nervous  matter,  in  the  egg,  and  in  vegetable  grains  of  various 
kinds,  points  to  a  possible  function  of  a  histogenetic  or  tissue-forming 
character. 

3.  Glycerine,  C3II5 .  (0H)3,  is  a  triatomic  alcohol  existing  in  the  fats 

1  See  "Watt's  Diet  of  Chem.  vol.  vii.  p.'  329. 


148  TEE  CHEMISTRY  OF  THE  BODY. 

of  the  body,  which,  as  will  presently  be  seen,  are  its  ethers.  It  also 
exists  in  palm  and  other  vegetable  oils,  and  it  is  one  of  the  by-products 
of  the  alcoholic  fennentation.  The  chemist  has  been  able  to  build  it 
up  synthetically  "  by  heating  for  some  time  a  mixture  of  ally!  tribro- 
mide,  silver  acetate  and  acetic  acid,  and  saponifying  the  triacetin  so 
obtained."  ("Witthaus.)  The  properties  of  glycerine  are  so  well  known 
as  scarceh'  to  require  description.  It  is  soluble  in  water  and  alcohol, 
but  is  insoluble  in  ether  and  chloroform.  It  is  a  good  solvent  for  many 
organic  matters,  as,  for  instance,  the  ferments  of  the  salivary,  gastric, 
and  pancreatic  juices. 

As  wiU  be  seen  in  describing  the  digestive  process,  glycerine  is  pro- 
duced during  pancreatic  digestion.  The  fat  of  the  food  is  decomposed 
by  the  action  of  the  pancreatic  ferment,  and  glycerine  is  set  free.  Some 
have  held  that  this  free  glycerine  is  instantly  absorbed  into  the  blood, 
and  that  in  the  blood  it  is  quickly  decomposed  into  simpler  substances. 
That  the  process  is  rapid  is  evident  from  the  fact  that  no  free  glycerine 
can  be  detected  either  in  the  bowel  or  in  the  blood,  and  even  after  the 
injection  of  glycerine  into  the  blood,  there  are  none  of  the  products 
of  its  oxidation  (formic  acid,  acetic  acid,  propionic  acid,  etc.).  The 
amount  of  carbonic  acid,  hoAvever,  is  increased,  and  consequently  it  has 
been  supposed  that  it  is  decomposed  into  carbonic  acid  and  water. 
Others  have  contended  that  glycerine  may  contribute  to  the  forma- 
tion of  glycogen,  the  carbo-hydrate  of  the  liver.  A  diet  rich  in  glycerine 
undoubtedly  increases  the  amount  of  glycogen  in  the  Kver,  but  it  is  not 
easy  to  follow  the  steps  of  the  process  by  which  this  may  be  accom- 
plished. Thus  "Ploesz  has  found  in  the  mine  of  animals  to  which 
glycerine  has  been  given  a  reducing  body  analogous  to  glucose,  but 
differing  in  having  no  action  on  polarized  light."  (Beaunis.)  This  body 
is  not  glucose,  but  has  been  supposed  to  be  an  aldehyde  of  glycerine, 
CgHgOg,  and  by  the  combination  of  two  molecules  of  this  substance, 
with  the  eKmination  of  water,  glycogen  may  be  formed.     Thus — 

2C3H,03        -         H,0        =        CeHioOj 

Aldehyde  of  glyceriue.  Glycogen. 

Again,  it  has  been  supposed  that  the  glycerine  may  not  be  absorbed,  but 
may  be  decomposed  in  the  intestine  into  various  acids,  and  in  particular 
propionic  acid,  which  may  then  form  propionates  voided  in  the  faeces. 
It  is  not  likely  that  the  whole  of  the  glycerine  is  thus  disposed  of.  A 
more  probable  theory  is  that  of  Beneke,  who  suggests  that  as  by  the 
action  of  the  gastric  juice  phosphoric  acid  is  set  free  from  the  phosphates 
of  the  food,  this  free  acid  may  imite  Avith  the  free  glycerine  to  form  the 
important  substance,  j)hospho-glyceric  acid,  which  again  is  concerned  in 


THE  NON-NITROGENOUS  MATTERS. 


149 


the  formation  of  lecithin.  (Beannis.)  On  the  whole,  I  am  of  opinion 
that  the  evidence  is  in  favour  of  the  view  that  glycerine  contributes  to 
the  formation  of  glycogen. 

4.  Phenol,  CgHg  .  OH,  phenic  acid,  carboKc  acid,  has  been  found  in 
small  quantities  in  the  urine  and  faeces,  and  is  probably  the  result  of 
pancreatic  digestion.  Staedeler  has  discovered  it  in  the  urine  of  the 
cow.  When  found  in  lurine,  it  is  not  in  the  free  state,  but  in  the  condition 
of  phenol-sulphuric  acid  or  j)henol-sulphate  of  potash,  CgHgO.SOg.OK. 
The  simultaneous  ingestion  of  phenol  and  of  sulphuric  acid,  or  of  a 
sulphate,  is  said  to  increase  the  amount  of  the  phenol-sulphates,  and  to 
cause  a  disappearance  of  the  ordinary  sulphates.  The  phenol  of  the 
urine  may  have  originally  been  formed  in  the  intestinal  canal,  but  it  is 
not  imjDrobable  that  some  substances  introduced  into  the  body  may  h& 
transformed  directly  into  phenol.  This  peculiar  combination  of  phenol 
and  sulphuric  acid  is  the  type  of  a  number  of  bodies  to  which  Baumann 
has  given  the  name  of  sulpho-conjugated  acids.  Phenol-sulphate  of 
potash  may  be  decomposed  by  acids  and  by  heat  into  phenol  and 
sulphuric  acid.  Many  other  compounds  of  a  similar  kind  exist,  such  as 
thymol,  pyrocatechin,  pyrogallic  acid,  nitro-phenol,  amido-phenol, 
sulpho-pyrocatechic  acid,  and  chresol-sulphuric  acid.  (Beaunis,  j). 
115.) 

2.  The  Fats. 


Animal  fats  exist  diu"ing  life  in  a  liquid  form,  contained  in  small  cells 
lying  in  the  meshes  of  connective  tissue, 
from  which  the  fluid  may  be  expelled  by 
pressure  (Fig.  62).  The  oils  thus  obtained 
have  been  termed  palmitin,  stearin,  and 
olein.  Stearin  is  the  most  consistent  of 
the  three,  while  olein  is  fluid  at  ordinary 
temperatures.  Human  fat  is  formed  chiefly 
of  a  mixture  of  palmitin  and  olein,  and 
contains  only  a  very  small  quantity  of 
stearin. 

Fats  consist  chemically  of  a  combination 
of  the  triatomic  alcohol  known  as  glycerine, 
CgHgOg,  with  a  fatty  acid.  Their  struc- 
ture may  be  best  comprehended  by  sup- 
posing that  they  are  built  on  the  type  of  ^^om'tiilm^^^^''  '^'^^^^'^^  quite  free 
three  molecules  of  water,  in  which  three 
atoms  of  hydrogen  are  replaced  by  three  equivalents  of  the  monatomic 


Fig.  62.— On  the  cooling  of  fat,  say  after 
death,  the  fatty  matters  may  assume 
the  forms  of  groups  of  needle-shaped 
crystals,  a,  Single  needles ;  b,  larger 
groups  of  the  same ;  c,  groups  of  needles 


150 


THE  CHEMISTRY  OF  THE  BODY. 


radicle  of  a  fatty  acid  and  the  remaining  three  hy  the  triatoniic  radicle 
glyceryl.     Thus — 


(H,0)3 

Water. 

(H,0)3 
Water. 


Radicle. 

C18H37 
Radicle. 

CisHgiO 

Radicle  of 
palmitic  acid. 

Radicle  of 
stearic  acid. 


H 


0 


Ho     +     0 


-        CifiH^iO 
Radicle  of  palmitic  acid. 

C18H.55O 
Radicle  of  stearic  acid. 


C3H5 

Glyceryl. 

C3H5 

Glyceryl. 


[  (Ci6H3iO)3G,H,  |0, 
1 


Palmitin. 


(Cl8H;,,0),Cft  |0, 

stearin. 


Of    a,HooOfi 


C„H„„0„ 


Olein. 


0,  .  3H.,0  or  CWH„„0„     +     3H.,0 


A  fat  may  thus  also  be  considered  as  a  compound  ether,  or,  in  other 
words,  as  consisting  of  palmitic,  oleic,  and  stearic  gl}^cerides,  variously 
mixed  together. 

Moleschott  found  in  the  body  of  a  man  of  thirty  years  of  age,  weigh- 
ing 63-65  kilogr.,  about  1566  gi-ammes,  that  is,  2*5  per  cent,  of  the  body 
weight.  Burdach  gave  an  estimate  of  5  per  cent.,  but  it  is  evident  the 
percentage  of  fat  will  vary  much  in  different  individuals.  The  follomng 
table  from  Gorup-Besanez^  gives  the  percentage  of  fat  in  the  chief  organs 
and  flmds  of  the  human  body — - 


Fluids. 

Percentage 
of  Fat. 

Tissue  or  Oeoan. 

Percentage 
of  Fat. 

Sweat, 

•001 

Vitreous  humour, 

•002 

Saliva, 

•02 

Cartilage,     - 

1-3 

Lymph, 

•05 

Bone,  - 

1^4 

Synovia, 

•06 

Crystalline  lens,  - 

2^0 

Liquor  amnii, 

•06 

Liver, 

2^4 

Chyle, 

•2 

Muscles, 

3  3 

Mucus, 

•3 

Hair,  - 

4^2 

Blood, 

•4 

Brain, 

8^0 

Bile,    - 

r4 

Egg,    -        - 

11  •G 

Milk,  - 

4-3 

Nerves, 

22-1 

Adipose  tissue,    - 

82-7 

Marrow  of  bone, 

96-0 

1.  Tripcdmitin,  C3H5(0  .  C-^^(^Il.^-fi).^,  exists  in  most  animal  and  vege- 
table fats,  and  especially  in  palm  oil.  It  occurs  in  the  form  of  crystalline 
plates,  very  soluble  in  ether,  and  sparingly  soluble  in  hot  alcohol.  It 
melts  at  50°  C,  and  solidifies  at  46°  C. 

2.  Tridearin,  C3H.(0  .  C^gH350)3,  is  the  chief  constituent  of  ordinar}^ 

^  Gorup-Besanez,  Physiologucken  Chemie,  1867,  p.  149. 


THE  NON-NITROGENO US  MA  TTERS.  151 

animal  fats.  It  is,  in  tlie  pure  state,  a  hard  crystalline  solid,  readily 
soluble  in  ether,  and  soluble  in  boiling,  but  scarcely  soluble  in  cold, 
alcohol. 

3.  Triolein,  03115(0  .  0;^gH330)3 .  SHgO,  is  the  principal  constituent  of  all 
fats  that  remain  fluid  at  ordinary  temperatures,  and  in  the  pure  con- 
dition it  is  a  colourless,  tasteless,  odourless  oil,  soluble  both  in  alcohol 
and  in  ether. 

4.  Trimargarin,  03115(0 .  0^711330)3,  has  been  obtained  artificially 
as  a  crystalline  solid.  By  this  name  is  sometimes  meant  a  mixture  of 
tripalmitin  and  tristearin. 

5.  Trihutijrin,  03115(0.041170)3,  is  found  in  butter.  It  is  a  pungent 
liquid,  and  Avhen  it  decomposes,  butyric  acid  is  set  free. 

6.  Trivalerin,  03115(0  .  05HgO)3,  exists  in  seal  oil,  and  in  the  fat  of 
some  marine  mammalia.  It  is  identical  with  the  phoceninc  of  OheAoreul. 
(Witthaus.) 

7.  Tricaproin,  03H5(0  .  0(iHi,0)3 ;  Trkaprylin,  O.^JiO  .  08H^50)3 ; 
and  Tricaprin,  03115(0 .  O^qH^qO).,,  are  found  in  milk,  butter,  and 
cocoa-butter. 

Fats  are  either  derived  from  the  fat  in  food  or  formed  in  the  body. 
Their  origin,  function,  and  ultimate  destination  will  be  fully  discussed 
in  treating  of  nutrition.  It  is  sufiicient  here  to  say  that  they  contribute 
largely  by  oxidation  to  the  production  of  heat,  and  that  they  also  are 
concerned  in  histogenetic  processes. 

3.  The  Carbo-Hydrates. 

The  name  of  this  important  group  indicates  that  they  may  be  re- 
garded as  composed  of  carbon  with  hydrogen  and  oxygen  in  the 
proportions  that  form  Avater.  Thus,  glucose  is  OgH^gOg,  or  0(H20)g. 
This  is,  however,  a  very  imperfect  view  of  their  chemical  constitution, 
as  there  are  chemical  considerations  which  point  to  some  of  the  carbo- 
hydrates being  aldehydes,  alcohols,  or  ethers.  They  are  classified  as 
follows,  the  -H  or  -  sign  indicating  that  they  are  dextro-  or  Isevo- 
rotatory  as  regards  polarized  light — • 


1.  Glucoses. 

2.  Sacc:haroses. 

3.  Amyloses. 

nlCsHisOg) 

"(Ci-^H^Ai) 

nlCgHioOg) 

-1- Glucose. 

+  Saccharose. 

+  Starch. 

(Dextrose). 

+  Lactose. 

+  Glycogen. 

C  hondroglucose . 

+  Maltose. 

+  Dextrin. 

-  Lasvulose. 

Cellulose. 

Mannitose. 

Gums. 

■f  Galactose. 

Inosite. 

CHj, 

OH 

(CH. 

1 

OH), 

COH 

Glucose. 

152  THE  CHEMISTRY  OF  THE  BODY. 

(1)  The  Glucoses. 

These  may  be  regarded  as  the  aldehydes  of  mannite,  and  they  con- 
tain in  their  rational  formula  the  group  of  atoms,  COH,  characteristic 
of  aldehydes.     Thus — 

CHjj .  OH 

I 
(CH .  0H)4  and 

CH. .  OH 

JIannite. 

1.  Glucose,  glycose,  grape  sugar,  diabetic  sugar,  dextrose,  CgHjgO^,,  exists 
in  fruits,  in  honey,  in  the  liver,  thymus,  heart,  lungs,  blood,  and 
muscles,  and  in  the  saliva,  sweat,  faeces,  blood,  and  urine  of  persons 
suffering  from  diabetes  mellitus.  Human  blood  contains  on  an  average 
about  "09  per  cent.  (Bernard.)  It  has  also  been  found  in  the  fluid  of 
the  amniotic  and  allantoic  sacs  of  herbivora,  and  in  the  lurine  of  the 
foetal  calf  and  foetal  sheep.  Glucose  may  be  crystallized  from  an 
aqueous  solution  in  white  spheroidal  masses  containing  1  molecule  of 
water,  and  from  alcohol  iu  transparent  anhydrous  prisms.  It  is  soluble 
both  in  hot  and  in  cold  Avater,  and  in  alcohol.  With  polarized  light, 
the  result  is  [a]D= +52°-85.  A  solution  of  glucose  heated  with  an 
alkali  gives  a  brown  or  yellow  colour,  from  the  formation  of  glucic  and 
melassic  acids.  In  alkaline  solutions,  glucose  reduces  salts  of  silver, 
bismuth,  mercury,  and  copper,  in  the  case  of  the  first  three,  the  metal 
being  precipitated,  whilst  cupric  are  reduced  to  cuprous  compounds, 
with  the  separation  of  cuprous  oxide. 

The  folloA\dng  are  the  chief  reactions  of  glucose  by  which  its  presence 
may  be  detected,  or  its  amount  in  any  fluid  determined — (1)  Mooi-e's 
test.  Heat  "with  an  .equal  quantity  of  solution  of  caustic  potash,  and  a 
yeUow  colour  is  produced,  and,  if  a  large  amount  of  sugar  is  present, 
the  colour  is  brown.  In  the  latter  case,  there  may  be  a  molasses-like 
smell.  (2)  Trojnmer's  test.  Add  to  the  solution  a  few  drojDS  of  a  Aveak 
solution  of  sulphate  of  copper,  then  a  little  of  a  solution  of  caustic 
potash ;  the  latter  precipitates  hydrated  cupric  oxide,  which  is  soluble 
in  excess  of  caustic  potash,  if  sugar  be  present.  Then  heat  to  near 
boiling,  and  a  deposit  appears  of  cuprous  oxide,  which  may  be  yellow, 
orange,  or  red,  according  to  the  amount  of  cuprous  oxide  reduced.  If 
a  large  amount  of  sugar  be  present  along  with  only  a  small  quantity  of 
cupric  oxide,  on  heating,  the  blue  fluid  may  become  yellow,  without 
precipitation  of  cuprous  oxide,  the  latter  being  held  in  solution  by  the 
excess  of  glucose.  (Witthaus.)  (3)  Fehling's  test.  A  solution  known  as 
"  Fehling's  solution"  is  thus  prepared — I.  Dissolve  51-98  grammes  of  pure 


THE  NON-NITROGENOUS  MATTERS.  153 

crystals  of  sulpliate  of  copper  in  500  c.c.  of  water  ■  II.  Dissolve  259-9 
grammes  of  pure  crystals  of  EocheUe  salts  (tartrate  of  soda  and  potash)  in 
1000  c.c.  of  a  solution  of  caustic  soda  ha-vang  a  specific  gravity  of  1"12. 
^\^len  required  for  use,  1  volume  of  I.  is  mixed  with  2  volumes  of  II. 
Keep  in  the  dark  in  a  stoppered  bottle,  having  the  stopper  parafiined. 
To  apply  the  test,  boil  4  or  5  c.c.  of  FehUng's  solution  in  a  test  tube ;  if 
it  remain  unaltered,  add  solution  containing  glucose  drop  by  drop,  and 
the  fluid  will  become  green,  and  a  red  or  yellow  precipitate  of  cuprous 
oxide  is  obtained.  The  reaction  is  precisely  the  same  as  in  Trommer's 
test.  In  both  we  have  an  alkaline  solution  of  cupric  oxide  along  with 
glucic  and  melassic  acids,  formed  by  the  action  of  the  caustic  alkali  on 
the  sugar,  and,  as  these  acids  have  a  strong  af&nity  for  oxygen,  they 
rob  the  cupric  oxide  of  oxygen,  reducing  it  to  cuprous  oxide,  which, 
being  insoluble  in  an  alkaline  fluid,  is  precipitated.  (4)  B'ottgers  test. 
A  few  cubic  centimetres  of  the  solution  of  glucose  are  mixed  in  a  test 
tube  with  an  equal  volume  of  a  solution  of  sodium  carbonate  (1  part 
of  crystallized  carbonate  of  soda  and  3  parts  of  water),  a  few  grains  of 
subnitrate  of  bismuth  are  added,  and  the  mixture  boiled.  In  the 
presence  of  sugar,  bismuth  is  thrown  down  by  reduction  as  a  brown  or 
black  powder.  (5)  Picric  acid.  To  a  solution  of  glucose  add  a  few  drops 
of  a  solution  of  picric  acid,  heat,  then  add  a  drop  or  two  of  caustic 
potash,  and  a  brownish-red  colour  is  obtained.  Other  substances  give  a 
similar  reaction,  such  as  creatinin.  (6)  Fermentation.  Mix.  a  solution 
of  glucose  with  yeast  in  a  large  test  tube,  and  invert  the  test  tube  so  as 
to  have  the  mouth  immersed  in  a  solution  of  glucose ;  keep  at  a  tem- 
perature of  25°  C.  for  ten  or  twelve  hoiurs,  and  a  quantity  of  gas, 
carbonic  acid,  wiU  collect  in  the  test  tube,  and  alcohol  ^xi\\  be  formed  in 
the  fluid.  (7)  MiLlder-Neuhauer  test.  A  solution  of  glucose  is  rendered 
faintly  blue  with  indigo  solution,  and  "faintly  alkaline  with  sodium 
carbonate,  and  heated  to  boiling  Avithout  agitation."  (Witthaus' 
Chemistry,  p.  219.)  It  turns  violet  and  then  yellow  without  agitation, 
but  if  it  is  shaken  the  blue  colour  is  restored.  (8)  Saccharimeter.  A 
solution  of  glucose  rotates  the  plane  of  polarization  to  the  right.' 

It  is  often  important  to  determine  quantitatively  the  amount  of 
glucose  or  diabetic  sugar  present  in  such  a  fluid  as  the  lu-ine.  The  fol- 
lowing are  the  methods  to  be  relied  on. 

(1)  Saccharimeter  or  Folarimeter. — Add  to  the  fluid  containing  glucose 
a  solution  of  acetate  of  lead,  and  filter.     Place  the  filtered  fluid  in  the 

^  The  precautions  to  be  observed  in  applying  any  of  the  above  reactions  for  the 
detection  of  sugar  in  the  urine  are  not  here  detailed,  as  these  are  the  special 
applications  of  general  methods  which  can  be  best  understood  and  appreciated  in 
the  clinical  work  of  the  hospital. 


154 


THE  CHEMISTLIY  OF  THE  BODY. 


tube  of  the  saccharimeter,  and  take  half  a  dozen  readings  of  the  angle 
of  deviation.  The  mean  will  represent  the  angle  of  rotation,  and  the 
percentage  of  sngar  is  determined  by  p  =  ^^.^^  x  I,  in  which  p  =  the  weight 
in  grammes  of  ghicose  in  1  c.c.  of  fluid,  a  =  the  angle  of  deviation,  and 
/  =  the  length  of  the  tube  in  decimetres.  The  numbers  52-85  indicate 
the  specific  rotatory  power  of  glucose  =  [a]  c. 

A  very  ingenious  spectropolarimetei'  has  been  invented  by  E.  v.  Fleischl  for 
the  determination  of  the  amount  of  ghicose  in  a  sohition.  It  is  specially  adapted 
for  the  estimation  of  diabetic  sugar  in  urine.  One  of  its  chief  advantages  is, 
that  it  avoids  the  difficulty  of  forming  a  judgment  as  to  the  identity  of  two 
coloured  surfaces,  as  has  to  be  done  with  one  of  the  usual  instruments.  (.See  p.  69, 
Fig.  2i.) 


Fio.  63. — Speotropolarimetur  ot  E.  v.  Fleischl. 

A  lamp  or  gas  flame  is  placed  opposite  the  end  of  the  instrument  shown  to  the 
right  of  the  figure.  The  light  passes  first  through  a  Nicol's  prism  h,  the  Polarizer, 
then  through  two  small  quartz  plates  cc,  so  placed  that  the  bisecting  plane  in 
which  they  meet  lies  horizontally.  The  one  quartz  plate  is  dextro-,  whilst  the 
other  is  Itevo-rotatory,  and  the  thickness  of  each  plate,  7 "75  to  8  mm.,  is  such 
that  the  green  rays  between  the  Fraunhofer  liiaes  E  and  b  of  the  spectrum  are 
circularly  polarized  through  an  angle  of  90°,  the  one  set  passing  through  the  upper 
quartz  to  the  left,  and  the  other  through  the  lower  qiiartz  to  the  right.  The 
light  then  continues  onwards  through  a  tubej^,  177  "2  mm.  in  length,  containing 
15  c.c.  of  the  solution,  and  having  flat  glass  plates  to  close  it  at  each  end.  It  then 
passes  through  a  second  Nicol  d,  the  Analyzer,  with  its  principal  axis  horizontal, 
like  that  of  the  first  Nicol  b,  and  it  will  be  evident  that  the  light  between  E  and  b, 
extinguished  by  circular  polarization  through  an  angle  of  90°  by  the  quartz  plates, 
will  not  pass  through  this  second  Nicol.  Finally,  the  light  passes  through  a 
direct  vision  spectroscope  e.  To  give  sharpness  of  definition  to  the  spectrum  thus 
obtained,  there  is  a  movable  vertical  slit  at  A-,  immediately  in  front  of  the  quartz 


THE  NON-NITROGENO US  MA  TTERS.  ]  55 

plates  c  and  c.  Suppose  then  that  the  tube  ff  contained  water  or  was  empty,  or 
suppose  it  not  to  be  in  its  position,  and  a  black  cloth  to  be  thrown  over  the  part 
of  the  instrument  at^so  as  to  exclude  light,  on  looking  through  a  small  telescope 
carrying  the  prisms  e,  two  beautifully  distinct  horizontal  spectra  are  seen,  one 
over  the  other,  and  separated  by  a  very  thin  dark  line.  Each  spectrum,  however, 
shows  a  dark  band  ia  the  green,  owing  to  the  extinction  of  that  part  of  the 
spectrum  by  the  right  and  left-handed  rotation  of  the  green  rays  by  the  quartz 
plates  through  90°,  and  the  two  bands  are  exactly  over  each  other,  so  that  the 
lower  edge  of  the  one  touches  the  upper  edge  of  the  other.  The  Analyzer  is  fixed  in 
a  tube  carrying  an  arm  bearing  a  vernier  g,  so  that  it  oan  be  rotated  round  the 
surface  and  near  the  border  of  a  circular  metal  disc  seen  in  section  at  h,  and  this 
disc  is  graduated  into  degrees.  The  two  bands  in  the  spectra  exactly  coincide 
when  the  zeros  of  the  vernier  and  of  the  scale  correspond.  If  now  the  tube  ff 
containing  the  solution  of  sugar  is  interposed,  the  two  bands  are  seen  to  be 
shifted — the  one  to  the  right  or  the  other  to  the  left,  according  to  the  direction 
of  rotation  by  the  substance  under  examination.  If  the  substance  be  glucose, 
which  is  dextro-rotatory,  then  the  band  corresponding  to  the  dextro-rotatory 
quartz  plate  will  be  pushed  to  the  right,  and  the  extent  of  the  movement  is 
measured  by  rotating  the  Analyzer  through  the  number  of  degrees  required  to 
cause  the  zero  points  again  to  coincide,  and  the  two  bands  are  made  also  exactly 
to  coincide  as  to  vertical  position.  Suppose  then,  that  to  produce  this  effect,  a 
rotation  of  6°  is  necessary,  then  the  fluid  in  the  tube  contains  6  per  cent,  of 
sugar,  that  is  6  grammes  in  100  cubic  centimetres.  The  scale  of  degrees  is  such 
that  each  degree  corresponds  to  1  per  cent,  of  sugar  in  the  given  length  of  column 
of  fluid  in  the  tube//.  The  green  rays  are  chosen  for  exclusion,  because  they  are 
the  most  suitable  in  the  case  of  urine,  which  absorbs  the  violet  rays  (those  having 
the  greatest  amount  of  rotatory  dispersion),  and,  as  already  explained,  the  exclu- 
sion of  these  rays  is  effected  by  the  determinate  thickness  of  the  quartz  plates. 
It  would  have  been  equally  easy,  by  altering  the  thickness  of  the  quartz,  to 
exclude  the  red  rays  ;  but,  as  their  rotatory  dispersion  is  small,  the  instrument 
would  not  then  have  been  so  sensitive,  or  the  blue  rays,  but  in  that  case  the  bands 
would  not  have  been  so  distinct.  This  instrument  gives  results  to  within  ^V 
per  cent,  of  sugar,  and  as  it  can  be  quickly  applied  without  the  use  of  monochro- 
matic light,  and  as  it  gives  the  percentage  amount  without  any  calculation,  it  is 
specially  adapted  for  the  wants  of  medical  men. 

(2)  Sir  William  FiobeH's  method. — Determine  the  specific  gravity  of  the 
fluid  at  25°  C,  add  yeast,  maintain  at  25°  C.  till  fermentation  stops  ; 
again  take  the  sjoecific  gravity,  and  each  degree  of  diminution  of  specific 
gravity  represents  •2196  gramme  of  sugar  in  100  c.c.  (or  1  grain  to  the 
ounce).  This  method  is  well  suited  for  the  determination  of  sugar  in 
urine. 

(3)  Volumetric  process  hy  Fehlingh  solution. — The  strength  of  Fehling's 
solution  is  such  that  to  reduce  the  cupric  to  cuprous  oxide  in  20  c.c. 
•1  gramme  of  glucose  is  required.  The  solution  of  glucose  is  diluted 
with  nine  times  its  bulk  of  water  and  placed  in  a  burette.  In  a 
porcelain  dish  20  c.c.  of  Fehling's  solution  are  mixed  with  40  c.c.  of  water 
and  2  c.c.  aq.  ammonia  and  heated  to  boiling  under  the  burette.     The  fluid 


156  THE  CHEMISTRY  OF  THE  BODY. 

in  the  burette  is  alloAved  to  mix  with  the  bhic  fluid  in  the  porcelain  dish, 
and  as  the  cupric  oxide  is  reduced  to  cuprous  oxide,  the  blue  colour 
gradually  disappears.  When  the  blue  colour  has  entirely  gone,  the 
number  of  c.c.  of  the  fluid  in  the  burette  is  read  off.  This  represents  the 
number  of  c.c.  containing  -1  gramme  of  glucose,  as  'l  gramme  is  required 
to  precipitate  all  the  cuprous  oxide  in  20  c.c.  of  Fehling's  solution.  To 
control  the  observation,  filter  the  fluid  in  the  porcelain  dish  and  divide 
into  three  portions.  To  the  first  add  a  few  drops  of  acetic  acid  and 
treat  with  a  solution  of  ferrocyanide  of  potassium.  If  the  reduction  has 
not  been  complete,  and  any  free  cupric  oxide  still  exists,  a  reddish-brown 
colour  is  obtained.  In  that  case,  enough  of  the  solution  in  the  burette 
has  not  been  added.  This  may  be  corroboi'ated  by  acidulating  the 
second  portion  with  a  drop  of  hydrochloric  acid  and  a  few  drops  of 
ammonium  sulphide,  which  mil  give  a  black  colour  ^^dth  any  free 
cupric  oxide.  To  the  third  portion,  in  the  event  of  the  first  two 
giving  no  reaction,  add  a  few  drops  of  Fehling's  solution  and  boil ; 
the  absence  of  any  yellow  colour  Avill  show  that  there  is  no  excess  of 
glucose,  that  is,  that  we  have  not  added  too  much  of  the  fliiid  from  the 
burette.  Suppose  40  c.c.  of  fluid  in  burette  has  been  used  and  that  it  was 
diluted  with  9  times  its  bulk  of  water.  This  would  represent  4  c.c. 
of  fluid  containing  -1  gramme  of  glucose,  that  is  2-5  per  cent. 

(4)  Pavijs  Gravimetric  method. — In  a  gravimetric  process  the  cuproiis 
oxide  is  carefully  collected,  dried,  and  weighed,  but  this  is  a  matter  of 
great  difficulty,  and  even  in  the  hands  of  skilful  manipulators  is  wanting 
in  precision.  It  occurred  to  Dr.  Pavy  to  dissolve  the  precipitated 
cuprous  oxide  and  then  to  throw  the  copper  down  in  the  metallic  form  by 
galvanic  action  upon  a  platinum  surface,  and  lastly  to  weigh  the  copper 
thus  deposited.  The  process  is  fully  described  in  Dr.  Pavy's  Croonian 
Lectures  on  Points  connected  vith  Diabetes,  pp.  41-49  (1878),  and  he  sums 
up  its  theory  as  follows — 

"  When  sugar  is  boiled  ■with  the  copper  solution  the  change  occurring  stands  in 
the  relation  of  one  atom  of  the  former  to  five  atoms  of  cupric  oxide.  One  atom  of 
sugar  is  oxidized  by,  or  reduces,  five  atoms  of  cupric  oxide.  This  is  the  founda- 
tion of  the  action  involved  in  the  operation  of  the  test,  and  the  calculation  of  the 
amount  of  sugar  present  is  made  accordingly.  Taking  63 '4  as  the  atomic  weight 
of  copper,  and  ISO  as  that  of  glucose  (CgHjaOg),  317  parts  of  copper  will  stand 
equivalent  to  180  parts  of  glucose.  Thus  one  part  of  copper  corresponds  to  "5678 
of  glucose,  and  in  calculating  the  amoi;nt  of  sugar  in  the  blood  analysis,  the  weight 
of  copper  deposited  has  only  to  be  multiplied  by  "5678  to  give  its  equivalent  in 
glucose.  The  quantity  of  sugar  in  the  amount  of  blood  taken  for  analysis  being 
thus  determined,  the  required  information  is  supplied  for  expressing  the  proportion 
for  1000  parts." 

The   glucose   found   in   the   alimentary  canal   is  derived  from  the 


THE  NON-NITROGENOUS  MATTERS. 


157 


conversion  of  starch  into  glucose  by  the  action  of  the  salivary 
and  pancreatic  juices.  This  glucose  is  absorbed  and  carried  to  the 
liver,  where  it  is  changed  into  glycogen,  the  peculiar  amylose  found 
in  that  organ  and  in  many  of  the  tissues.  Part  of  the  glucose  in  the 
bowel  may,  by  fermentations,  be  changed  into  lactic  or  butyric  acids — 
CgHi^Og  =  2(C3Hg03),  lactic  acid,  or  2{G^B.^^0^)  =  3{C^B.f)^),  butyric  acid. 
The  physiological  importance  of  glucose  will  be  shown  in  discussing 
the  glycogenic  function  of  the  liver  in  relation  to  nutrition.  By  its 
oxidation  into  carbonic  acid  and  water,  heat  will  be  produced.  There 
is  also  evidence  to  show  that  the  consumption  of  glucose  is  one  of  the 
chemical  phenomena  connected  with  muscular  action,  and  with  the 
activity  of  protoplasm  generally. 

2.  Chonclro-glucose  is  a  substance  formed  by  the  action  of  nitric  acid 
upon  cartilage.  It  reduces  cupric  oxide  to  cuprous  oxide  and  is  said  to 
be  fermentable,  producing  melitose,  a  kind  of  sugar  obtained  from 
manna. 

3.  Lcevulose,  uncrystallizable  sugar,  is  found  in  the  intestine  as  the 
result  of  the  inversion  of  cane  sugar  by  the  action  of  a  ferment,  when 
cane  sugar  is  changed  into  equal  parts  of  dextrose  (glucose)  and 
Isevulose.  It  has  been  discovered  in  the  blood,  urine,  and  muscles. 
Lsevulose  is  uncrystallizable,  very  soluble  in  water,  insoluble  in  alcohol, 
and  it  reduces  copper  salts.  With  polarized  light,  it  has  a  powerful 
laevo-rotatory  action,  -  [a]D=  -  106°. 

4.  Mannifose,  or  Mannite,  is  a  yellow  uncrystallizable  sugar,  like 
glucose  in  its  general  character,  but  having  no  action  on  polarized  light. 

5.  Galactose  is  formed  by  the  action  of  dilute  acids  on  lactose,  or  milk 
sugar.  With  polarized  light,  [«]d=  +83-33.  Nitric  acid  converts  it 
into  mucic  acid. 

6.  Inosite,  Muscle  sugar,  is  a  sugar 
found  in  muscles  (specially  the  muscle 
of  the  heart),  in  the  kidneys,  liver, 
lungs,  pancreas,  spleen,  suj^ra-renal 
bodies,  brain,  spinal  cord,  testes,  blood, 
and  in  urine.  (Beaunis.)  Professor 
Kiilz  asserts  that  it  exists  even  in  nor- 
mal urine ;  it  certainly  is  found  in  the 
urine  of  diabetes,  and  sometimes  in  that 
of  uraemia.  It  forms  long  clear  shining 
crystals  (Fig.  64)  with  two  molecules 
of  water  of  crystallization,  and  "usu-  Fig.  64. -crystals  of  inosite. 
ally  arranged  in  groups  having  a  cauliflower-like  appearance."  (Wit- 
thaus.)     Inosite  is  readily  soluble  in  water  and  with  difficulty  in  alcohol, 


158  THE  CHEMISTRY  OF  THE  BODY. 

and  is  insoluble  in  absolute  alcohol  and  ether.  It  has  no  action  on 
polarized  light.  It  is  not  fermentable.  In  the  presence  of  inosite, 
hydrated  cupric  oxide  is  dissolved  in  excess  of  caustic  potash,  but  on 
boiling  the  blue  fluid  no  reduction  occurs,  as  with  glucose.  The  follow- 
ing reaction  has  been  said  to  distinguish  inosite,  but  it  is  difficult  of 
application  and  does  not  give  good  results  with  inosite  in  a  fluid  con- 
taining other  organic  matters.  Srhprer's  test.  Evaporate  the  fluid  A\nth 
a  drop  or  two  of  nitric  acid  on  a  platinum  plate  nearly  to  dryness  : 
moisten  the  residue  with  ammonium  hydrate;  add  a  drop  or  two  of  a 
solution  of  chloride  of  calcium  and  again  evaporate  to  dryness — a  rose- 
pink  colour  may  appear. 

The  origin  of  inosite,  in  addition  to  Avhat  may  be  introduced  in  the 
food,  and  its  physiological  uses  are  unkno^vn. 

(2)  The  Saccharoses. 

These  are  regarded  as  condensed  glucoses,  inasmuch  as  they  arc 
formed  by  the  comliination  of  two  molecides  of  a  glucose  with  the  loss 
of  one  molecule  of  water.     Thus — 

QHioOe  +  C6Hj.,06  -  H,0  =  Ci,H.,,Oii. 

1.  Cane  sugar,  beet  sugar,  does  not  occur  in  the  body,  but  in  relation 
to  nutrition  and  to  other  carbo-hydrates  it  is  important  to  notice  some 
of  its  properties.  Only  those  not  familiar  to  everyone  are  here  alluded 
to.  It  does  not  reduce  cupri-potassic  solutions  in  the  cold,  but  it  may 
do  so  with  prolonged  heating,  with  excess  of  alkali.  Aqueous  solutions 
■with  polarized  light  give  [ft]D=  +  73°-8.  When  boiled  with  water,  it 
is  converted  into  dextrose  and  IffiA^dose.     Thus — 

C10H22O11  +  H.O  =  CgHioOg  +  CfiHi.Os. 

Saccharose.  Dextrose.    Lajvulose. 

The  solution  now  shows  left-handed  rotation  ^rith  polarized  light  as  the 
left-handed  rotation  of  Isevulose,  [ajo  =  106°,  is  only  partially  antagonized 
by  the  right-handed  rotation  of  dextrose,  [a]o  =  52°-85.  "With  active 
yeast  saccharose  is  first  inverted  by  a  special  soluble  ferment  produced 
by  the  yeast  cell,  and  then  there  is  fermentation  of  the  glucose  thus 
formed. 

2.  Lactose,  milk  sugar,  as  the  name  implies,  occurs  in  milk.  It  exists 
in  the  form  of  prismatic  crystals,  soluble  in  hot  or  cold  water,  and  in 
acetic  acid,  but  insoluble  in  alcohol  and  ether.  "With  polarized  light  the 
action  is  la]o=  +59-3.  Dilute  mineral  acids  change  it  into  galactose, 
and  nitric  acid  oxidizes  it  to  mucic  and  oxalic  acids.  It  reduces  Fehlino's 
solution.  When  a  solution  of  lactose  is  mixed  ^ith  yeast  the  alcoholic 
fermentation  goes  on  slowly,  and  during  putrefaction  lactose  produces 
lactic  acid. 


TEE  NON-NITROGENOUS  MATTERS.  159 

When  introduced  into  the  alimentary  canal,  lactose  is  changed  into 
galactose  (a  glucose)  which  is  then  absorbed.  "With  regard  to  the  origin 
of  lactose  in  the  cells  of  the  mammary  gland,  there  are  diverse  opinions  as 
to  whether  it  may  be  formed  from  glucose  taken  in  the  food  or  produced 
from  starch.  The  injection  of  glucose  into  animals  during  lactation 
has  given  unreliable  results,  and  it  cannot  be  said  that  the  amount  of 
lactose  in  the  milk  of  such  animals  was  sensibly  increased.  On  the 
suppression  of  lactation,  sugar  may  appear  in  the  urine  but  it  has  not 
been  satisfactorily  determined  whether  it  is  glucose  or  lactose. 

3.  Maltose  is  a  sugar  formed  during  the  glucose-forming  action  of  the 
salivary  and  pancreatic  ferments  and  of  diastase  on  starch.  It  crys- 
tallizes like  glucose,  but  differs  from  that  sugar  in  being  less  soluble 
in  alcohol  and  in  exerting  a  dextrogyratory  power  three  times  as  great. 

(3)  The  Amtloses. 

These  may  be  regarded  as  the  anhydrides  of  the  glucoses. 

CfiHiaOg  -   HoO  =  CgH^oOg. 
Glucose.  Starch. 

They  are  readily  changed  by  the  action  of  ferments  and  by  weak 
sulphuric  acid  into  glucose.  Chemists  hold  that  the  formulae  of  the  amy- 
loses  should  be  expressed  as  a  multiple  of  CgH^oOg,  that  is  ??(CgH^()05). 

1.  Starch  does  not  exist  in  the  human  body,  but  forms  an  important 
element  of  food.  A  solution  gives  with  polarized  light  [a] ^  =  -t- 216°. 
Heat  causes  starch  grains  to  swell  and  burst,  and  at  200°  C.  it  is  changed 
into  dextrin.  It  is  also  changed  into  dextrin  by  heating  with  water  at 
160°  C,  and  prolonged  heating  changes  it  into  glucose.  Starch  is  also 
changed  into  glucose  by  hydrochloric  and  oxalic  acids.  It  is  insoluble 
in  alcohol,  ether,  and  cold  water.  Cold  water  causes  the  starch  grains 
to  swell  enormously  and  to  become  glutinous,  forming  starch  paste  or 
hydrated  starch.  If  then  boiled  ^vith  water  a  solution  of  starch  is 
obtained.  A  dilute  solution  of  iodine  gives  a  violet-blue  ■\\ith  starch, 
and  if  to  a  solution  of  starch  made  blue  ^vith  iodine,  a  solution  of 
a  neutral  salt  is  added  there  separates  a  blue  flocculent  deposit  of 
the  so-called  iodide  of  starch.  As  will  be  seen  in  the  description  of 
digestion,  starch  is  converted  into  sugar  by  the  action  of  the  sali'\'ary  and 
pancreatic  jmces. 

2.  Glycogen  is  a  form  of  animal  starch  found  in  the  liver,  placenta, 
cartilage  cells,  pus  cells,  colourless  blood  corpuscles,  muscular  tissue,  and 
in  embryonic  tissues  generally.  It  may  be  prepared  from  the  liver  by 
either  of  the  two  following  methods  :  (1)  Claude  Bernard's  method.  The 
liver  is  cut  into  small  pieces  and  thrown  into  boiling  water ;  the  frag- 
ments are  then  bruised  in  a  mortar  for  a  (quarter  of  an  hour  in  a  very 


160  THE  CHEMISTRY  OF  THE  BODY. 

little  -water.  This  matter  is  then  submitted  to  pressure  and  the  fluid 
obtained  is  mixed  with  animal  charcoal  and  filtered.  The  opalescent 
filtrate  is  mixed  ^nth  five  times  its  volume  of  alcohol  of  38°  to  40° 
strength,  and  the  glycogen  is  precipitated.  The  precipitate  is  collected 
and  washed  -\nth  alcohol,  and  to  obtain  the  glycogen  pure  it  is  boiled  in 
a  concentrated  solution  of  caustic  potash  and  is  then  reprecipitated  with 
alcohol.  The  alcoholic  precipitate  is  freed  from  the  caustic  potash  by 
being  washed  with  distilled  water.  (2)  BrilcJ:e's  method.  The  liver  is 
thrown  into  boiling  water.  "\Mien  hard  it  is  bruised  in  a  mortar  -with  a 
little  water,  and  the  bruised  matter  is  heated  gently  for  half  an  hour  in 
a  little  more  water.  The  milky  fluid  is  then  poured  off"  and  is  replaced 
by  water.  This  is  again  boiled  and  the  fluid  again  poured  off"  repeatedl)^ 
until  the  water  has  an  opalescent  tint.  These  washings  are  collected, 
cooled,  and  filtered,  and  acetic  acid  and  potassio-iodide  of  mercurj^  are 
added  so  as  to  form  a  precipitate.  This  is  filtered,  and  the  filtered 
liquid  is  heated  "vWth  alcohol  which  precipitates  the  glycogen.  This  is 
then  collected,  washed  with  alcohol,  and  purified  by  the  caustic  potash 
method  above  described.  The  C[uantity  may  also  be  estimated  by 
Briicke's  method,  by  weighing  the  amount  of  the  precipitate,  or  the 
glycogen  may  be  converted  into  glucose  by  the  action  of  weak  acids, 
and  the  glucose  thus  formed  maj^  be  fermented.  Briicke's  method 
gives  the  best  results  both  qualitatively  and  quantitatively. 

When  so  obtained,  glycogen  is  a  snow  white,  odourless,  tasteless 
powder,  soluble  in  water,  and  insoluble  in  alcohol  and  ether.  Its  solu- 
tions with  polarized  light  are  dextrogyrous  to  about  three  times  the 
extent  of  those  of  glucose.  In  the  presence  of  glycogen,  hydrated 
cupric  oxide  is  soluble  in  caustic  potash,  but  no  reduction  occurs  on 
boiling.  Iodine  gives  ^^^th  glycogen  a  wine-red  colour.  When  boiled 
with  nitric  acid,  oxalic  acid  is  formed.  The  ferments  of  the  salivary 
glands,  and  of  the  pancreas,  glycerine-extracts  of  the  liver,  pancreas, 
muscle,  lung,  and  brain,  and  dilute  mineral  acids  change  it  into  glucose. 

The  iDhj'siological  importance  of  gljxogen  will  be  discussed  in  treating 
of  the  glycogenic  function  of  the  liver  in  its  relation  to  nutrition. 

3.  Dextrin  is  a  substance  obtained  by  subjecting  starch  to  a  dry  heat 
of  175°  C,  or  by  heating  starch  ^vith  dilute  sulphuric  acid  to  90°  C,  or 
by  the  action  of  the  diastase  in  infusion  of  malt  upon  hydrated  starch. 
It  is  a  slightly  yello^^'ish  powder,  soluble  in  water,  forming  mucilage,  and 
its  solutions  ^vith.  polarized  light  give  [a]D  ==  -i- 138° -88.  Dextrin  is 
said  to  occur  in  the  blood  and  in  muscle,  and  when  a  solution  is  injected 
into  the  blood  it  is  changed  into  glucose. 

4,  Cellulose  is  the  basis  of  vegetable  tissues.  (See  Vines'  Physiology  of 
Plants,  Lect.  i.)      A  variety  of  cellulose  has  been  found  by  Schafer  in 


THE  NON -NITROGENOUS  MATTERS.  161 

the  mantles  of  Fi/rosomidce,  Salpidce,  and  Fhallusia  mamillaris.  The 
reactions  of  this  substance  leave  no  doubt  as  to  the  identity  of  animal 
and  vegetable  cellulose.^  A  similar  substance  is  said  to  exist  in  the 
skin  of  the  silkworm. - 

4.  The  Non-Nitrogenous  Organic  Acids. 

These  are  acids  formed  in  the  body  or  introduced  in  the  food,  and 
usually  united  "with  bases.  Representatives  of  four  groups  of  these 
organic  substances  occur  in  the  body,  belonging  to  the  acetic  acid  series, 
the  giycollic  acid  series,  the  oxalic  acid  series,  and  the  oleic  acid  series. 

( 1 )  Acids  related  to  the  Moxato jiic  Alcohols  ok  Acetic  Acid  Series. 

These  are  a  series  of  acids,  all  monobasic,  and  related  to  a  series  of 
radicles,  CHo,  CgH^,  etc.,  each  member  of  the  series  differing  from  the 
one  before  it  by  an  additional  increment  of  CH.,.  They  may  be  regarded 
as  formed  on  the  type  of  Avater  in  which  the  radicle  of  the  acid  is  sub- 
stituted for  an  atom  of  hydrogen,  or  there  is  a  substitution  of  0  for  H., 
in  the  radicle,  and  this  altered  radicle  is  then  united  to  hydroxyl — 

C.,H,0 


H 
CsHg    -    H2    +    0    =    C.,H,0     :    then     : 

H 


H 


Ethyl.  Radicle  of  acetic  acid.  Acetic  acid. 

Another  view  is  that  they  are  derived  from  the  primary  monatomic 
alcohols  by  the  substitution  of  0  for  H^  in  the  gTouj)  CH^ .  OH — 

CH3  -  CH,  -  CH.  -  CHo .  OH,  Normal  butyl  alcohol. 
CH3  -  CHo  -  CHo  -  CO  .  OH,  Normal  butyric  acid. 

The  annexed  series  (see  page  162)  is  sometimes  termed  the  fatty  acid 
series,  because  the  higher  substances,  such  as  palmitic,  margaric,  and 
stearic  acids,  exist  in  fats.  (See  Fats,  p.  150.)  The  follo^ving  are  the 
characters  of  the  chief  members  of  the  group.-^ 

Formic  acid,  CH^O^,  is  a  colourless  liquid  of  strong  and  pic[uant  odour ; 
volatile  at  100°  C.  without  residue  ;  is  not  precipitated  by  the  nitrate  of 
mercury ;  heated  Avith  concentrated  sulphuric  acid,  it  decomposes  into 
water  and  carbonic  oxide,  CH^Oo  =  CO  +  HgO. 

Acetic  acid,  C^H^O^,  transparent  foliated  crystals ;  changes  at  17°  C.  to 
a  colourless  fluid,  of  a  piquant  characteristic  odour,  and  of  a  very  acid 
taste ;  volatile  Avithout  residue.  It  is  not  precipitated  by  perchloride  of 
iron,  but  if  we  saturate  the  acid  vnth.  ammonia,  the  licjuid  becomes  dark- 

^  Schafer,  Annates  Chem.  Pharm.  clx.  312. 
^  De  Lucca,  Comptes  Bendus,  lii.  102,  Ivii.  43. 

^  From  the  Appendix  to  Beauuis'  Physiologie  Humaine,  vol.  ii.  p,  1441. 
I.  L 


162 


THE  CHEMISTRY  OF  THE  BODY. 


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THE  NON-NITROGENOUS  MATTERS.  163 

red  (acetate  of  iron) ;  white  crystals  are  precipitated  by  the  protonitrate 
of  mercury. 

Propionic  acid,  CgHgO^,  is  a  colourless  liquid,  of  an  odour  like  that  of 
acetic  acid;  volatile  at  142°  C;  soluble  in  water;  from  an  aqueous 
solution,  chloride  of  calcium  precipitates  it  in  oily  drops.  Treated  with 
alcohol  and  sulphuric  acid  it  gives  out  an  odour  of  fruit,  due  to  the 
formation  of  propionate  of  ethyl.  The  propionate  of  sodium  is  much 
more  soluble  than  the  acetate. 

Bidijric  acid,  C^HgOg,  is  a  colourless  liquid,  of  the  odour  of  "vinegar,  or 
of  rancid  butter  when  it  is  impure,  and  soluble  in  water,  alcohol,  and 
ether;  volatile  at  160°  C. ;  it  is  precipitated  from  concentrated  solutions 
by  chloride  of  calcium  in  oily  drops.  Heated  ^nth  alcohol  and  sid- 
phuric  acid,  it  gives  butyrate  of  ethyl,  having  an  odour  of  strawberries. 

Capmic  acid,  CgH^202J  ^^  ^  colourless  liquid,  oily,  of  the  odoiu:  of  per- 
spiration ;  volatile  at  202°  C. ;  almost  insoluble  in  water ;  miscible  in 
alcohol  and  ether  in  all  proportions ;  the  caproate  of  baryta  dissolves 
in  1 2  parts  of  cold  water. 

Capnjlic  acid,  CgHj^g02,  is  an  oily  liquid  of  the  odour  of  perspiration : 
crystallizes  at  12°  C. ;  insoluble  in  water;  miscible  in  alcohol  and 
ether  in  all  proportions;  the  caprylate  of  baryta  is  soluble  in  125  parts 
of  cold  water. 

Capric  acid,  C^QHgoOg,  solid,  of  the  odoui'  of  perspiration ;  fusible  at 
70°  C. ;  slightly  soluble  in  water ;  miscible  in  alcohol  and  ether  in  all 
proportions ;  the  caprate  of  baryta  is  almost  insoluble  in  cold  water. 

Palmitic  acid,  C^gHggOg,  in  crystalline  masses,  inodorous,  insipid; 
fusible  at  62°  C. ;  insoluble  in  water,  soluble  in  alcohol,  very  soluble  in 
boiling  alcohol,  ether,  and  chloroform. 

Stearic  acid,  C;^gHgg02,  a  crystalline  mass,  white,  inodorous,  insipid  ; 
fusible  at  69°  C. ;  insoluble  in  water,  less  soluble  in  alcohol  than  pal- 
mitic acid,  soluble  in  boiling  alcohol,  ether,  and  chloroform.  Stearate 
of  lead  is  insoluble  in  ether. 

All  of  these  acids  may  be  changed  by  oxidation  to  a  lower  term  or 
member  of  the  series,  and  ultimately  into  carbonic  acid  and  water. 
Thus— 

CsHgOa  4-  O3  =  C2H4O2  +  CO2  +  H,0  ;  CgH^Oa  +  03  =  CH^O^  +  H^O  +  CO^  ; 

Propionie  Acetic  acid.  Acetic.  Formic, 

acid. 

CH202  +  0  =  C02  +  H20. 

Formic. 

It  would  appear  also  that  in  fermentations  the  higher  fatty  acids  may 
produce  acids  lower  in  the  series  simply  by  decomposition,  -ndthout 
oxidation,  and  thus,  in  the  decomposition  of  a  fat  (when  it  is  rancid), 
we  may  find  propionic,  acetic,  and  formic  acids.     Probably  such  de- 


164  THE  CHEMISTRY  OF  THE  BODY. 

compositions  occur  in  the  intestinal  canal,  and,  the  free  acids  uniting 
with  bases,  form  salts  which  appear  in  the  faeces. 

(2)  Acids  related  to  the  Diatomic  Alcohols,  or  Glycols. 

These  are  derived  from  diatomic  alcohols,  or  glycols,  by  the  sub- 
stitution of  1  atom  of  oxygen  for  2  of  hydrogen,  just  as  the  acetic  acid 
series  is  derived  from  monatomic  alcohols.  But  the  glycols  contain 
two  groups  of  CHg .  OH,  each  of  which  may  yield  an  acid.     Thus — 

CHo .  OH         CHo .  OH         CO  .  OH 

i  ■  I  I 

CHs  .OH         CO  .  OH  CO  .  OH 

Bthene  glycol.  Glycollic  acid.  Oxalic  acid. 

Such  acids  are  diatomic,  and  the  hydrogen  in  each  of  the  hydroxyls 
may  be  replaced  by  a  radicle.  There  is  thus  a  double  series  of  these 
acids. 

(a)  The  Glycollic  Acid  Series,  CnHonOg. 

These  are  formed   by  the  partial  oxidation   of  the   corresponding 

glycol.     Thus — 

CHo .  OH  +   0.,         =         CH„ .  OH   +   H„0 

I     "  "  I    " 

CH., .  OH  CO  .  OH 

Glycol.  Glycollic  acid. 

From  one  point  of  view,  carbonic  acid  belongs  to  this  series,  being  the 
lower  homologue  of  glycollic  acid,  from  which,  however,  it  differs  in 
being  dibasic.  The  physiological  importance  of  this  acid  will  be  con- 
sidered under  Nutrition  and  Respiration.  The  remaining  terms  of  the 
series  are  as  follows — 

Glycollic  acid,     .         -         -     C2H4O3 

T-      ,  ■        -J  f^-rrn    rSour  milk,  contents  of  stomach, 

Lactic  acid,  -         -         -     CaHgOa  -^     intestine,  and  in  many  organs. 

Ethyleno-lactic  acid,  -        -     CgHgOa    Muscle  juice. 
Butylactic  or  oxybutyric  acid,  C4H8O3 
Oxyvaleric  acid,  -         -     CgHjoOs 

Oxycaproic  acid,  -        -     CeHjgO^ 

1.  Glycollic  acid,  C2H4O3,  forms  deliquescent  needle-shaped  crystals, 

very  soluble  in  water,  in  alcohol,  and  in  ether.     It  does  not  occur  in 

the  body,  but  it  is  of  physiological  importance  in  its  relation  to  glycolle 

or  glycocin,  one  of  the  substances  occurring  in  glycocholic  acid.     (Sec 

pp.  90  and  106.)     Thus,  glycocoUe  is  derived  from  glycocollic  acid  by 

the  substitution  of  the  radicle  NHg  for  one  of  the  hydroxyls  of  the 

latter — 

CHa  .  OH  CH2 .  NHs 

I  I 

CO  .OH  CO  .  OH 

Glycollic  acid.  Glycocolle. 


THE  NON-NITROGENOUS  MATTERS.  165 

2.  Lactic  acid,  CgHgOg,  exists  in  two,  if  not  three,  isomeric  conditions 
of  physiological  importance.     First,  there  is  the  variety  of  lactic  acid 
regarded  chemically  as  ethyleno-lactic  acid,  as  it  contains  the  group  CHg, 
CH2.OH 

thus,  CHg  ,  to  distinguish  it  from  the  other  two  varieties,  which 

CO.  OH 

are  called  ethylidene  lactic  acids,  as  these  contain  the  group  CHg,  thus, 

CH3 

CH  .  OH.     The  ordinary  lactic  acid  of  fermentation  (as  in  sour  milk), 

CO  •  OH 

and  the  variety  of  lactic  acid  found  in  muscle  juice,  to  which  the  names 
of  sarcolactic  acid  or  paralactic  acid  have  been  given,  belong  to  the 
ethylidene  division,  whilst  muscle  juice  also  yields  the  other  kind, 
ethyleno-lactic  acid. 

a.  Ordinary  lactic  acid  (optically-inactive  ethylidene  lactic  acid)  is  a 
sjT:'upy  liquid  very  soluble  in  water,  alcohol,  and  ether.  It  is  readily 
oxidized  into  formic  and  acetic  acids.  It  may  occur  in  gastric  juice,  in 
chyme,  in  sour  milk,  in  the  blood  of  leucocythsemia  and  in  pus,  and  it 
is  usually  associated  with  alkaline  bases,  forming  lactates.  Ordinary 
lactate  of  zinc  (Zn(C3H503)2  +  3H2O)  differs  from  sarcolactate  of  zinc 
in  the  amount  of  the  water  of  crystallization. 

h.  Sarcolactic  ov  paralactic  acid,  sometimes  also  called  optically-active 
ethylidene  lactic  acid,  occurs  in  muscle  juice,  and  can  be  separated  from 
it  in  the  form  of  a  salt  of  zinc  (Zn(CoH503)o  -I-  2H2O).  It  differs  from 
the  two  isomers  in  having  an  influence  on  polarized  light,  its  solutions 
being  dextro-,  whilst  its  salts  are  laevo-rotatory.  Thus,  with  the  solu- 
tion [a]  D=  +  3°*5  ;  with  the  zinc-salt  solution  =  -  7°'6  ;  and  with  the 
lime  salt  {2\C&{Q,^f)o).?\  +  ^^2^)  solution  =  -  3°-8.  Oxidation  con- 
verts it  into  formic  and  acetic  acids.  Sarcolactic  acid,  as  already 
mentioned,  is  found  in  muscles.  Lactic  acid  also  is  met  with  in  many 
organs,  but  whether  it  is  of  this  variety  or  not  has  not  been  determined.^ 

c.  Ethyleno-lactic  acid  is  also  found  in  muscle  juice ;  like  paralactic  acid 
it  forms  a  salt  of  zinc  containing  two  molecules  of  water  of  crys- 
tallization, and  when  oxidized  by  chromic  acid  it  yields  malonic  acid. 

Lactic  acid  may  be  formed  in  the  intestinal  canal  by  fermentation,  or 
it  may  be  formed  in  the  muscles.  In  the  muscles,  no  doubt,  it  is 
derived  from  glycogen,  glucose,  or  inosite.  As  it  does  not  appear 
except  in  small  quantities  in  the  excretions,  it  is  no  doubt  rapidly 
oxidized  in  the  blood  or  tissues,  being  ultimately  resolved  into  carbonic 

^  As  to  the  mode  of  preparing  it,  see  Gamgee's  Physiological  Chemistry,  vol.  i. 
p.  361. 


166 


THE  CHEMISTRY  OF  THE  BODY 


acid  and  water.  The  injection  of  solutions  into  the  blood  is  followed 
by  an  increase  of  the  carbonates  in  the  urine,  and  one  can  follow  the 
steps  of  the  deoxidation  process  thus — 

2(C3He03)  +  0,  =  C^HgO,  +  200^  +  2B..f) ;   C4H8O,  +  O3  =  CaHgO,  +  CO,  +  H,0, 

Lactic  acid.  Butyric  Butyric 


Butyric 
acid. 


Propionic 
acid. 


and  then  from  propionic  downwards,  as  given  in  the  preceding  account 
of  the  oxidation  of  the  fatty  acids. 

3.  Oxycaproic  acid  or  leucic  acid,  CgHjoOg,  although  it  has  not  been 
found  in  the  body,  merits  attention  on  account  of  its  relation  to  leucin. 
(See  p.  91.)  Leucin  may  be  regarded  as  oxycaproic  acid,  in  which  NHg 
is  substituted  for  hydroxyl.     Thus — 

CH„ .  OH  CH., .  NH.. 


(CH,), 

I 

CO.  OH 

Oxycaproic  acid. 


(CH2)4 
I 
CO.  OH 

Leucin. 


Oxalic  acid, 

-     CHoO^ 

Malonic  acid, 

-     C,-R,0, 

Succinic  acid, 

-     C4H6O4 

Adipic  acid, 

-     CgHjoOj 

Pimelic  acid, 

-     C,Hi,0, 

Suberic  acid, 

-     GsHi.O, 

Azalic  acid. 

-     C9H16O4 

Sebacic  acid. 

■     CioHjgOj 

Roccellic  acid. 

-       Ci,H3,04 

{/3)  The  Oxalic  Acid  Series,  CJi,,_.fii. 
These  are  obtained  from  the  glycols  by  complete  oxidation,  and  as 
they  are  dibasic  thej"  may  form  two  series  of  salts.     The  following  con- 
stitute the  group— 

Uriue,  etc. 

Identical  with  nicotic  acid  in  tobacco. 

Urine,  spleen,  thyroid,  thymus. 

Action  of  nitric  acid  on  oleic  acid,  suet,  etc. 

Action  of  nitric  acid  on  oleic  acid,  wax,  sper 

maceti,  etc. 
Action  of  nitric  acid  on  cork,  fats,  etc. 
Action  of  nitric  acid  on  fats. 
Action  of  nitric  acid  on  fats. 
From  the  lichen  Roccella  tinctoria. 

The  most  important  of  these  physiologically  are  oxalic  and  succinic 

acids. 

(1)  Oxalic  acid,  C2H20^,  occurs  in  the  urine  in  the  form  of  oxalate  of 

lime,  more  especially  after  ingestion  of  the  leaves  of  the  Avood  sorrel  (oxcUis 

acetosella),  rhubarb,  cinchona,  or  other  herbs  containing  it.  It  abounds  in 
the  urine  of  herbivora.  In  the  pure  state  it  occurs 
in  the  form  of  white  crystals,  having  an  acid  taste, 
soluble  in  water  and  alcohol,  and  decomposed  into 
carbonic  acid  and  carbonic  oxide  by  the  action  of 
sulphuric  acid.  The  most  important  salt  is  oxalate 
of  lime,  which  appears  in  the  urine  in  the  form 

of  beautiful  octahedral  crystals  or  bodies  of  a  dumb-bell  form.     (Sec 

Fig.  65.) 


.♦ 


Fio.  65.  —  Octahedral 
crystals  of  oxalate  of 
lime. 


THE  NON-NITROGENOUS  MATTERS.  167 

Whilst  oxalic  acid  may  be  introduced  in  food,  there  can  be  no  donbt 
that  it  is  also  fornaed  in  the  body  itself,  and  in  this  connection  it  is 
important  to  observe  that  it  may  be  formed  by  the  decomposition  both 
of  non-nitrogenous  and  nitrogenous  matter.  Thus  it  may  be  produced 
by  the  oxidation  of  many  organic  substances,  alcohol,  glycol,  sugar, 
glycerine,  etc.,  and  by  the  decomposition  of  albuminoids.  Experiment 
indicates  that  it  may  arise  from  the  incomplete  oxidation  of  luric  acid. 
Thus  the  injection  of  uric  acid  and  of  urates  into  the  blood  increased 
the  amount  of  oxalate  of  lime  in  the  urine.  (Wohler  and  Frerichs  quoted 
by  Beaunis.)  The  process  by  which  this  may  take  place  has  been 
already  explained  in  treating  of  uric  acid  (see  p.  99),  and  it  is  sufficient 
to  say  here  that  uric  acid  may  be  supposed  to  yield  urea,  allantoin,  and 
oxalic  acid,  and  that  allantoin  may  be  further  resolved  into  oxalic  acid. 
It  is  a  well  knoAvn  clinical  fact  that  in  persons  consuming  a  rich 
nitrogenous  diet,  and  by  insufficient  exercise  arresting  or  hindering 
efficient  oxidation,  the  urine  frequently  contains  deposits  of  lu-ic  acid 
and  of  oxalate  of  lime  alternately. 

2.  Succinic  acid,  C4^Hg04,  has  been  detected  in  urine  after  the  use  of 
asparagus  and  of  various  fruits  containing  malic  acid  and  asparagin, 
and  in  many  of  the  tissues  and  organs,  such  as  the  spleen,  thymus, 
thyroid,  and  in  the  pathological  fluids  of  hydrocele  and  ascites.  It 
appears  in  large  clear  prisms  or  hexagonal  plates,  acid  in  taste,  soluble 
in  water,  and  slightly  soluble  in  ether  and  cold  alcohol.  "When 
oxidized,  it  yields  butyric  acid. 

As  to  its  origin,  Meissner  and  Koch  have  shown  that  the  artificial 
digestion  by  gastric  juice  of  malate  of  lime  and  of  asparagin  yields 
succinic  acid.  As  after  a  meal  rich  in  asparagin  and  malates  there  is 
not  much  of  the  succinic  acid  eliminated  by  the  bowels  or  kidneys,  it  is 
probably  reabsorbed  and  oxidized  in  the  blood,  and  resolved  into  carbonic 
acid  and  water,  passing  through  the  intervening  stages  of  butyric,  pro- 
pionic acid,  etc. 

C4H6O4  =  CsHgO.,  -)-   CO.,  etc.,  or 

Succinic         Propionic 
acid.  acid. 

C4He04  +   H2  =   CiHgO.  -t-   0... 

Succinic  Butyric 

acid.  acid. 

(3)  Acids  kelated  to  the  Allvlic  Alcohols. 

A  number  of  bodies  belongs  to  this  series  in  Avhich  the  carbon  of  the 
hydrocarbon  is  non-saturated,  thus  difl'ering  from  the  hydrocarbons 
related  to  the  monatomic  and  diatomic  alcohols.     Thus  the  formula  of 

p    XT 

allylic  alcohol  is     ^    5     q,  in  which  it  is  evident  that  two  atomicities  are 


168  TJIE  CHEMISTRY  OF  THE  BODY. 

unsatisfied.  Related  to  such  alcohols  arc  the  acids  of  the  acryllic  series 
in  the  same  manner  :is  the  fatt}'  acids  are  related  to  the  monatoniic 
alcohols.     Thus — 

aHs      CM,  I  Q      CMfl  I  0      C3H5      C3H5  I  ^      C3H3O  I  ^. 

Ethyl.  Ethj-lic  Acetic  acid.  Allyl.  Allylic  Acryllic 

alcohol.  alcohol.  acid. 

The  substances  having  the  general  formula  C„H^,„_20o  belonging  to  tliis 
group  are — 

Acryllic  acid,    -     C3H4O0       -     By  oxidation  of  acrohbi,  an  aldeliyde  produced  by 

the  action  of  sulphuric  acid  on  glycerine. 
Crotonic  acid,  -     C4HeO^       -     Obtained  from  croton  oil. 

Angelic  acid,     -     CgHgO.j       -     In  angelica  root,  chamomile  Howers,  crotou  oil. 
Oleic  acid,         -     (l^^^fi.^    -     Fats. 

Okie  acid,  C;^gH3^0o,  as  already  shown,  page  150,  occurs  in  the  glycci'ic 
ether  olein,  one  of  the  common  fats.  It  is  an  oily  liquid,  above  14°  C. ; 
yellow,  inodorous,  insipid ;  insoluble  in  water,  soluble  in  alcohol,  ether, 
and  chloroform.  At  4°  C.  it  becomes  a  crystalline  mass,  having  a  beauti- 
ful pearly  appearance.  When  heated  in  air  it  is  decomposed  with 
formation  of  hydrocarbons,  volatile  fatty  acids,  and  sebacic  acid. 
(Witthaus.)  Nitric  acid  oxidizes  it,  forming  volatile  fatty  acids  and  also 
acids  belonging  to  the  oxalic  acid  seizes,  adipic,  suberic,  etc.  It  dissolves 
the  fatty  acids.  Oleic  acid  has  been  found  in  small  quantity  in  the 
blood  and  bile,  and  in  considerable  amount  in  the  intestine. 


Chap.  XI.— THE  GASES. 

The  gases  of  the  body  consist  of  oxygen,  nitrogen,  carbonic  acid, 
hydrogen,  carburetted  hydrogen,  and  sulphuretted  hydrogen.  These 
gases  exist  either  free  in  certain  cavities  of  the  body  or  are  dissolved  in 
certain  fluids. 

(1)  Free  Gases. 

1.  Oxygen  is  found  in  the  pulmonary  passages  and  in  the  intestinal 
tube.  The  oxygen  of  the  lungs  comes  directly  from  the  atmosphere  of 
the  air ;  while  that  of  the  intestinal  tube,  which  is  in  small  quantity,  is 
no  doubt  introduced  "with  food  and  drink.  Oxygen  may  be  simply 
dissolved  in  the  fluid,  or  it  may  be  in  a  state  of  combination  with  haemo- 
globin.    (See  p.  119.) 

2.  Nitrogen  is  also  found  in  the  lungs  and  in  the  intestinal  canal. 
According  to  Chevreul,  the  great  intestine  contains  usually  more  than 
the  small  intestine,  a  fact  which  would  indicate  that  a  portion  of  the 
nitrogen  may  be  derived  from  other  sources  than  atmospheric  air. 


THE  GASES. 


169 


The  following  tables  chiefly  compiled  by  Beaunisi  shoAv  the  amount 
of  the  gases  in  various  fluids,  the  gas  being  reduced  to  the  volume  they 
would  occupy  at  0°C  and  760  mm.  pressure — 


o 

10 

_^ 

CO 

, 

Cl 

o 

0 

— ' 

10 

Tj- 

0 

s 

o 

^^ 

0 

. — 1 

0 

Ci 

^H 

o 

O 

o 
o 

^ 

^ 

0 

«D 

00 

0 

0 

^ 

r^ 

_l 

01 

^        3 

CM 

10 

•     '— ' 

Cl 

t:) 

r- 

0 

C-1 

<N 

•    10 

00 

0 

0 
0 

1— 1 

0 

0 

CO 

0 

^il^ 

CO 

r^ 

1— 1 

^ 

CO 

r- 

l— 

r- 

00 

CO 

^a^ 

«3 

CO 

ro 

(N 

G5 

g 

Cl 

LO 

CO 

s  ^' 

o 

0 

05 

0 

0 

0 

1 

P 

g 
< 

^g"S| 

tH 

0 

P 

CO 

0-i 

lO 

. 

lO 

-* 

0 

b 

s 

tJ* 

0 

0 

CO        g 

■"^ 

(M 

g 
^ 

t^ 

(M 

l^- 

era 

^, 

0 

0 

0 

CO 

0 

„      p 

T'      : 

■;i' 

H 

C4 

CM 

»o 

;z; 

00 

i-H 

0 

05 

12; 

CO 

CO 

0 

o 

o 

'^ 

'"' 

0 
0 

Ol 

=« 

CO 

OJ 

LO 

0 

CO 

0 

1 

1 

M 

m     ^ 

0 
b 

0 

6 

ip 

b 

< 
H 

0 

C-) 

b 

• 

go 

<» 
^ 
r- 

ip 
0 

0 
'?'       : 

b 

0 

0 

05 

00 

C5 

0 

b 

CO 

b 

o*. 

CO 

rr\ 

0 

-* 

CO 

r^ 

0 

p 

b 

o 

o 

O 
m 

SO 

b 

p      : 
b 

00 

0 

0 

M 

0 

0 

b 

02 

b 

o 

o 

0 

b 

1; 

CO 
CO 

0 

p 

CO 

p 

CO 

p 

b 

z 

fel 

.a 

o 

r^ 

eo 

0 

iz; 

s 

0 

CO 

r^ 

'"' 

H 

95 

CO 

T' 

!>. 

H 

CO 

"* 

CM 

< 
Cl5 

o 

-V 

'"' 

0 

00 

^ 

W 
0 

b 

C5 

CO 

b 

f3 

0 

0 

t^ 

r- 

^ 

in 

^ 

0 

0 

-* 

^ 

0 

1 — 1 

CO 

1        fe 

a 

0 

C) 

^H 

CO 

^ 

-+ 

CO 

CM 

;      o 

M 

>o 

lO 

0 

G5 

0 

C-1 

"J 

m 

r-~ 

CO 

-      g§ 

0 

00 

s    ■■ 

30  S" 
CO  1 

■P 

CO 

CM 

CO 

i 

T 

1— H 

>H 

Tj* 

CO 

»-o  £ 

00 

^•2  5 

<)  "S 

CO 

00 

IN 

CO 
00 

CO 
CO 

CO 

P 
00 

(N 

10 

1 

1—5 
1— 1 

10 

CO 

'- 

• 

•         • 

• 

'C 

■ 

■ 

■ 

p 

0 
a 
0 

c" 

..  s 

., 

0 

0 

a" 

' 

•^ 

(1> 

S       &D 

<i 

•^ 

(D 

ri 

SJO 

H 

< 
i5 

0 

1 

(U       0 

0 

H 

0 
cS 

U 

0 

0 

^ 

0     m 

0 

!^ 

0 

M 

=s  3 


-4J 

IM 

,% 

■  -. 

-a 

a 

4H 

." 

htl 

!=> 

W 

Tl 

3.  Hydrogen  has  been  found  in  small  quantity  in  the  air  of  expiration 
and  also  in  the  intestinal  canal ;    it  is  said  to  increase  in  the  great 

^  Beaiinis,  Physiologie  Humahie,  vol.  i.  p.  71. 


170  THE  CHEMISTRY  OF  THE  BODY. 

intestine  during  a  milk  diet  and  to  reach  a  minimum  during  a  meat  diet. 
Its  origin  in  the  intestine  is  probably  due  to  fermentation. 

4.  Carbonic  acid  also  exists  in  the  lungs  and  intestinal  canal.  In  the 
lungs  it  is  derived  from  the  blood,  and  in  the  intestinal  canal  it  may 
come  partly  also  from  this  source,  but  it  is  no  doubt  chiefly  due  to  chemi- 
cal decomposition.  The  gas  may  be  simply  dissolved  or  it  may  be 
loosely  united  to  the  carbonates  and  alkaline  phosphates. 

5.  Carhurettecl  liijdrogeri  has  been  found  in  the  great  intestine,  where  it 
is  said  to  exist  to  the  amount  of  from  5  to  10  per  cent.  It  is  increased 
by  a  leguminous,  and  falls  to  a  minimum  during  a  milk,  diet.  It  is  the 
result  of  decomposition. 

6.  Sidjihiiretted  hydrogen  is  occasionally  found  in  the  intestinal  canal 
and  results  from  the  decomposition  of  the  albuminous  constituents  of 
the  food  or  from  biliary  matters,  both  of  Avhich  contain  sulphur. 

Chap.  XII.  -THE  CHEMICAL  REACTIONS  IN  THE  LIVING  ORGANISM. 

Hitherto  we  have  been  describing  the  substances  obtained  by  chemical 
processes  from  dead  animal  matter,  or  from  the  secretions  or  excretions 
of  the  body.  It  is  manifestly  a  much  more  difficult  task  to  attempt  to 
follow  the  chemical  reactions  which  occur  in  the  living  body,  and  it  may 
be  at  once  admitted  that  much  of  our  knowledge  of  such  phenomena  is 
based  upon  inferences  collected  from  the  general  facts  observed  by  the 
physiological  chemist  when  he  analyzes  the  substances  obtained  from 
the  body,  and  studies  hoAv  they  are  affected  by  oxidizing  and  deoxidiz- 
ing agents,  into  what  simpler  substances  they  may  be  decomposed,  or 
what  more  complex  substances  may  be  formed  by  their  combination. 
"VYe  are  still  ignorant  of  the  exact  phenomena  and  conditions  of  those 
obscure  chemical  processes  which  occur  in  living  tissue,  and  which 
appear  to  be  absolutely  necessary  for  the  manifestation  of  vital  action, 
inasmuch  as  it  is  impossible  to  submit  living  tissues  to  the  ordinary 
processes  of  chemical  analysis,  even  on  a  microscopic  scale,  without  de- 
stroying their  vitality. 

The  principal  chemical  reactions,  however,  may  probably  be  classed 
into  the  great  divisions  of  oxidation,  decomposition,  reduction,  syn- 
thesis, and  fermentation. 

A.  Oxidation. 

Oxidation  is  the  most  common  chemical  reaction  in  the  living 
organism.  The  albuminates,  fats,  and  carbohydrates,  by  union  vdth. 
oxygen,  form  a  series  of  compounds,  somewhat  simpler  in  chemical 
composition,  and  lower  in  molecular  weight  than  themselves.      From 


CHEMICAL  REACTIONS  IN  THE  LIVING  ORGANISM.      VJ\ 

these,  by  a  continued  process  of  oxidation,  bodies  still  less  complex  in 
cbemical  composition  are  formed,  and  so  on  in  successive  stages  until 
the  elements  which  at  first  existed  in  albuminates  noAV  appear  under  the 
form  of  urea,  carbonic  acid,  and  water,  and  those  of  the  carbohydrates 
and  fats  as  carbonic  acid  and  water.  At  present  it  is  impossible  to 
demonstrate  the  successive  phases  through  which  albumin  may  have  to 
pass,  but  there  is  little  doubt  that  many  of  these  have  been  observed  by 
chemists  in  the  laboratory.  Thus,  by  oxidation,  albumin  has  been  re- 
solved into  leucin,  tyrosin,  glycocin,  and  fatty  acids ;  uric  acid  into 
urea,  allantoin,  oxalic  acid,  and  carbonic  acid ;  guanin  into  xanthin, 
oxaluric  acid,  and  urea ;  creatin  into  sarcosin  and  urea,  and  fats  into 
the  Avhole  series  of  fatty  acids.  It  has  also  been  found  that  the  intro- 
duction into  the  living  body  of  one  or  other  of  these  substances  has 
l)een  followed  by  the  appearance  in  the  secretions  of  an  increase  of  the 
materials  into  which  this  body  may  be  resolved.  Thus  the  introduction 
of  uric  acid  increases  the  amount  of  urea  and  of  oxalate  of  lime  excreted. 

The  oxygen  of  the  air  introduced  by  respiration  is  the  agent  which 
effects  the  oxidations  ;  but  it  is  remarkable  that,  while  in  the  laboratory 
these  oxidations  only  take  place  at  a  high  temperature  and  with  very 
powerful  oxidizing  agents,  such  as  permanganate  of  potash  or  nitric 
acid,  in  the  living  condition  they  occur  at  the  temperature  of  the  body 
and  with  much  greater  rapidity.  To  explain  this,  it  has  been  assumed 
that  the  oxygen  of  the  tissues  is  in  the  condition  of  ozone,  which  is 
known  to  have  strong  oxidizing  powers  even  at  comparatively  low 
temperatures.  Thus,  at  the  temperature  of  the  blood,  and  more 
especially  in  the  presence  of  alkalies,  or  of  alkaline  carbonates,  fats, 
glucose,  and  organic  acids  may  be  oxidized  by  ozone,  but  not  by 
ordinary  oxygen.  (Gorup-Besanez.)  No  proof,  hoAvever,  has  been 
offered  that  ozone,  O3,  exists  in  the  blood ;  indeed,  its  presence  has  been 
expressly  denied  by  Schonbein.  But  oxygen  in  the  nascent  state,  0, 
that  is  at  the  instant  it  has  been  set  free  from  ozone,  O3,  or  from  ordinary 
oxygen,  O2,  or  from  any  chemical  substance  containing  it,  is  well  knoAATi 
to  have  powerful  oxidizing  properties,  and  it  has  been  suggested  that  it 
is  thus  liberated  in  some  of  the  chemical  processes  occurring  in  the 
body.  It  has  also  been  pointed  out  by  Hoppe-Seyler,  Pfliiger,  and 
others  that  the  heat  formed  by  molecular  oxidation  is  quicldy  carried 
away,  and  that  the  mean  temperature  of  the  tissues  is  no  direct  measure 
of  the  heat  produced  in  them.  Thus,  a  high  temperature  Avill  be 
associated  Avith  the  oxidation  of  an  atom  of  carbon  or  an  atom  of 
hydrogen,  in  the  body  as  out  of  it,  but  in  the  body  the  heat  so  pro- 
duced is  quickly  diffused. 

Much  discussion  has  also  taken  place  as  to  Avhether  oxidations  occur 


172  THE  CHEMISTRY  OF  THE  BODY. 

in  the  tissues  or  in  the  blood.  There  can  he  no  doubt  that  oxidations 
occur  chiefly,  if  not  wholly,  in  the  tissues.  As  first  shoAvn  by  Spal- 
lanzani,  and  corroborated  by  many  modern  physiologists  (Valentin, 
Liebig,  Claude  Bernard,  Hermann,  and  Paul  Bert),  living  tissues  con- 
sume oxygen  and  produce  carbonic  acid.  On  the  other  hand,  blood 
left  to  itself  in  a  vessel  produces  carbonic  acid  and  consumes  oxygen, 
but  this  is  the  beginning  of  putrefactive  changes.  A  stream  of  oxygen 
passed  through  fresh  blood  does  not  increase  the  amount  of  carbonic 
acid  given  ofi'  which  would  be  the  case  if  oxidation  occurred  in  that 
fluid.  Pyrogallic  acid,  ^\liich  is  readily  oxidized,  if  injected  in  con- 
siderable qviantity  into  the  blood,  quickly  appears  in  the  urine,  showing 
that  it  has  passed  through  unchanged.  But  living  tissues  immersed  in 
blood  use  up  its  oxygen  and  produce  carbonic  acid.  The  fact  that 
nitrites  are  converted  into  nitrates,  sulphites  and  hyposulphites  into  sul- 
phates, and  that  organic  acids,  such  as  malates  and  tartrates,  are  changed 
into  carbonates  when  passed  through  the  body,  would  at  first  sight 
indicate  that  oxidations  may  occur  in  the  blood;  but  even  these  changes 
would  appear  to  depend  on  the  living  tissues,  as  lactate  of  soda  in  con- 
tact with  blood  remains  unaltered,  but  if  injected  into  a  vein  in  a  living 
animal,  it  is  quickly  decomposed,  "nath  the  formation  of  carbonates, 
which  then  appear  in  the  urine. 

One  must  avoid  entertaining  too  mechanical  a  view  of  the  so-called 
oxidations  in  living  matter.  There  is  no  such  phenomenon  as  the 
direct  union  of  oxygen  with  carbon  or  with  hydrogen,  as  in  burning 
these  in  the  laboratory.  If  this  were  the  case,  there  would  be  oxida- 
tions strictly  so  called,  and  we  Avould  find  a  constant  relation  between 
the  amount  of  oxygen  used  and  the  amount  of  the  combustion  products. 
No  such  parallelism  can  be  traced,  nor,  in  many  cases,  can  even  the 
products  of  combustion  be  estimated  quantitatively.  Thus,  one  is  led 
to  infer  that  oxidations  are  one  stage  of  complicated  processes,  possibly 
analogous  to  those  of  fermentation  or  putrefaction.  On  the  oxidation 
processes  occurring  in  the  body,  animal  heat,  mechanical  work,  and 
innervation  largely  depend. 

B.  Reduction. 

The  phenomena  of  reduction,  which  are  so  important  in  the  life  of  a 
plant,  do  not  occiu"  so  frequently  in  the  animal  body.  The  formation 
of  fat  from  carbohydrates  is  an  example  :  the  carbohydrates  lose  oxygen, 
and  become  transformed  into  fats.  The  formation  of  indol,  of  tri- 
methylamine,  and  the  conversion  of  benzoic  acid  into  quinic  acid,  of 
iodates  and  bromates  into  iodides  and  bromides,  and  of  indigo-blue  into 
indigo-white,  during  the  passage  of  these  substances  through  the  body, 


CHEMICAL  REACTIONS  IN  THE  LIVING  ORGANISM.     173 

are  no  doubt  examples  of  reduction.  It  is  likely  also  that  reductions 
and  oxidations  may  form  part  of  the  same  process,  or  the  one  process 
may  be  carried  through  before  the  other.  Thus,  malic  acid  by  reduction 
becomes  succinic  acid,  which  is  then  oxidized  into  carbonic  acid  and 
water. 

C.  Decomposition. 

By  decomposition  we  mean  the  splitting  up  of  an  organic  substance 
into  two  or  more  chemical  compounds,  the  combined  molecular  weight 
of  which  is  exactly  equal  to  the  molecular  weight  of  the  first  substance. 
Thus,  taurocholic  acid  may  divide  into  choloidic  acid  and  taurin — 
CosH4gNS07        =        C2H7NSO3        +        C.,4H3s04 

Taurocholic  acid.  Taurin.  Choloidic  acid. 

Occasionally,  by  dehydration  or  the  removal  of  water,  a  simpler  body 
may  be  formed.     Thus,  with  the  aid  of  heat,  cholalic  acid  may  be  con- 
verted into  dyslysin  and  water,  and  creatin  into  creatinin  and  water — 
C24H40O5        =.        C.^HggO.        +        2H,0 

Cholalic  acid.  Dyslysin. 

C4H9N3O2         =  C4H7H3O  +  H2O 

Creatin.  Creatinin. 

Sometimes  a  molecule  of  water  may  be  removed,  and  the  residue 
may  then  split  up  into  simpler  compounds.     Thus,  oxalic  acid  may  be 
divided  into  carbonic  acid,  carbonic  oxide,  and  water — 
C2H2O4       -       H2O      =       CO.      +      CO 

Oxalic  acid. 

It  would  appear  in  some  instances  that  a  compound  must  combine 
with  water  before  splitting  up.  This  occurs  in  the  saponification  of 
fats,  and  in  the  decomposition  of  glycocholic  acid  into  cholalic  acid  and 
glycocin — 

C,6H43N06  +  H^O  =  C24H40O5  +  C2H5NO2 

Glycocholic  acid.  Cholalic  acid.  Glycocin. 

In  like  manner,  creatin  may  be  resolved  into  urea  and  sarcosin,  and 
urea  into  carbonic  acid  and  ammonia — 

CH4N2O       +       H2O       =       CO2    +    2NH3 

Urea.  Ammon.  Carbonate. 

A  special  form  of  decomposition  is  dissociation  where  a  compound 
resolves  itself  into  two  or  more  simpler  bodies  under  altered  physical 
conditions.  Thus,  oxy-hsemoglobin  in  the  diminished  pressure  of  a 
partial  vacuum,  and  with  the  aid  of  heat,  gives  up  its  oxygen,  and 
resumes  it  when  the  conditions  return  to  those  of  ordinary  atmospheric 
pressure  and  a  temperature  of  15°  C.  Bonders  has  suggested  that  a 
dissociation  process  may  occur  in  respiratory  exchanges.  (See 
Eespiration.) 


174  THE  CHEMISTRY  OF  THE  BODY. 

D.  Synthesis. 

The  formation  of  organic  substances  by  synthesis  in  the  li\ang  animal 
body  is  still  very  imperfectly  understood,  but  it  is  interesting  to 
observe  that  many  nitrogenous  organic  compoimds  have  been  formed 
synthetically  by  the  chemist  in  the  laboratory.  Thus  urea,  hippuric 
acid,  glycocin,  tavu-in,  sarcosin,  creatin,  glucose,  and  oxalic,  lactic, 
succinic,  benzoic,  propionic,  acetic,  and  formic  acids  have  been  formed 
artificially ;  but  as  yet  it  has  been  impossible  to  prepare  the  higher 
members  of  the  series.  It  ^"s  probable  that  in  the  living  body  more 
of  the  nitrogenous  compounds  are  formed  by  analytical  than  by  synthe- 
tical processes.  One  well-kno'wn  example  of  a  synthetical  process  is 
the  formation  of  hippuric  acid  after  the  introduction  of  benzoic  acid 
\vith  food  or  medicine.  In  these  circumstances,  benzoic  acid  unites 
with  glycocin  to  fomi  hippuric  acid,  which  makes  its  appearance  in  the 
urine — 

OyHfiO.,       +       aHsNO.,       -       CgHgNOs       +       H.O 
Benzoic  acid.  Glycocin.  Hippuric  acid. 

In  some  cases  there  may  be  a  simple  union  of  this  kind,  but  in  most 
the  process  is  probably  much  more  complicated.  Thus,  a  complex 
substance  may  be  decomposed  or  oxidized,  and  the  simpler  products 
are  then  used  to  build  up  another  complex  body.  For  example,  the 
ingestion  of  toluol  is  followed  by  the  appearance  of  hippuric  acid  in  the 
urine.  Here  toluol  by  oxidation  becomes  benzoic  acid,  and  this  com- 
bining with  glycocin  produces  hippuric  acid.  Many  organic  acids  must 
thus  be  built  up,  by  the  union  of  various  substances  with  glycocin. 
Again,  when  taui'in  is  given  to  a  living  animal,  tauro-carbamic  acid 
appears  in  the  urine,  by  the  imion  of  the  taurin  ^^•ith  cyanic  acid. 
Again,  aromatic  bodies  unite  with  sulphuric  acid  to  produce  conjugated 
sulpho-acids.  Thus,  phenol  is  followed  b}^  the  appearance  of  phenol- 
sulphate  of  potash  or  soda,  cresol  by  cresolsulphate,  etc.  There  may 
also  be  in  the  first  instance  oxidations,  such  as  benzol  into  phenol, 
anilin  into  amidophenol,  and  then,  as  explained,  phenol  gives  rise  to 
phenolsulphate. 

Syntheses  pla}-  an  important  part  in  building  up  the  complex  bodies 
existing  in  living  matter,  and  we  may  consider  that  substances  so  all- 
important  as  fats,  lecithin,  and  other  compounds  existing  in  nervous 
matter,  haemoglobin  itself,  and  albuminous  bodies,  are  thus  formed. 
How  such  processes  are  accomplished  is  not  kno'siTi,  nor  must  we  sup- 
pose that  there  is  only  one  way  by  which  a  complex  chemical  substance 
may  be  formed.  It  has  been  conjectured  that  the  elimination  of  water 
plays  an  important  part  in  synthetic  operations,  and  that  the  bodie.=! 


CHEMICAL  REACTIONS  IN  THE  LIVING  ORGANISM.       175 

thus  formed  may  be  regarded  as  anhydrides  of  substances  produced  by 
the  combination  of  the  simpler  bodies.  Much  of  our  knowledge  on 
these  points  is  still  obscure,  but  it  is  remarkable  that  the  triumphs  of 
chemical  science  are  in  the  synthetic  production  of  complex  organic 
bodies,  and  it  is  not  unlikely  that  each  successive  step  in  this  direction 
will  lead  to  a  better  understanding  of  the  similar  processes  occurring  in 
the  body  in  the  upbuilding  of  its  tissues. 

E.  Fermentation. 

Certain  substances  have  been  long  known  to  possess  the  property  of 
exciting  chemical  changes  in  matters  with  which  they  come  into  con- 
tact. Such  substances  have  been  named  by  chemists  ferments,  and  the 
process  is  known  as  fermentation.  As  fermentation  plays  a  very 
important  part  in  nature,  and  as  in  recent  times  it  has  been  supposed 
to  be  the  explanation  of  many  processes  occurring  in  the  body,  and  to 
account  for  the  origin  of  not  a  few  forms  of  disease,  namely,  those 
included  under  the  generic  name  of  zymotic,  it  is  necessary  to  refer  to 
it  here  somewhat  in  detail. 


Chap.  XIII. —FERMENTATION. 

The  processes  included  under  the  name  fermentation  are  so  important 
as  to  demand  careful  study,  more  especially  in  these  days  when  they 
are  known  to  be  of  wide  application  to  many  phenomena  of  the  living 
body,  and  also  to  some  of  the  jDhenomena  of  disease.  Not  a  few  trans- 
formations occurring  in  the  body,  more  especially  during  the  process 
of  digestion,  are  of  the  nature  of  fermentations ;  and  it  is  highly 
probable  that  changes  of  a  similar  kind  are  involved  in  nutrition.  It  is 
now  also  generally  acknowledged  that  fevers  and  epidemic  diseases  owe 
their  origin  to  the  action  of  fermentive  agents,  and  that  as  we  gather 
knowledge  of  the  natural  history  of  these  agents,  their  conditions  of 
vitality,  their  mode  of  growth,  their  reproductive  j)rocesses,  and  the 
substances  they  produce,  we  may  hope  either  to  suppress  them  or  to 
confine  their  action  within  narrow  limits.  Further,  the  study  of  fer- 
mentation throws  a  flood  of  light  on  many  of  the  general  phenomena  of 
biology  in  the  lower  plants  and  animals,  and  lays  a  sound  foundation 
or  the  appreciation  of  physiological  processes,  as  these  occur  in  the 
higher  animals  and  in  man. 

When  a  fluid  ferments,  it  becomes  clearer  or  more  muddy,  as  the 
case  may  be,  and  it  usually  froths  and  gives  ofi"  a  gas.  This  is  well 
seen  if  the  sweet  juice  of  a  plant,  such  as  grape  juice,  is  exposed  to  the 
fair.      The  clear  fluid  becomes  turbid,  a  froth  gathers  on  the  surface 


176  THE  CHEMISTRY  OF  THE  BODY. 

owing  to  the  evolution  of  gas,  the  temperature  of  tlie  fluid  rises,  and  a 
slimy  deposit  gathers  at  the  bottom  of  the  vessel.  These  physical 
changes  are  also  known  to  be  associated  with  chemical  changes. 
Alcohol  and  various  other  substances  are  now  found  in  the  fluid,  and 
the  gas  given  off  is  carbonic  acid,  whilst  the  sugar  has  been  used  up, 
so  that  at  the  end  of  the  j^rocess  it  has  entirely  disappeared.  Further, 
there  is  a  change  of  a  biological  character,  for  if  the  slimy  deposit  at  the 
bottom  of  the  vessel  be  examined  with  the  microscope,  it  will  be  found 
to  contain  numerous  minute  unicellular  organisms,  various  species 
probably  of  Toridce  or  Saccharomijcctes,  Avhich  were  very  few  in  number  at 
the  beginning  of  the  process.  Some  of  these  phenomena  must  have 
been  known  from  the  most  distant  times,  indeed  since  men  began  to 
drink  the  fermenting  juice  of  the  grape,  or  ynne,  but  the  one  that 
specially  caught  their  attention  was  the  effervescence  or  frothing,  and 
as  it  resembled  the  bubbling  of  the  surface  of  a  boiling  fluid,  such  a  pro- 
cess Avas  called  a  fermentation  (from  fervere,  to  boil).  The  practice  of 
distillation,  by  which  the  alcohol  was  separated  from  the  rest  of  the 
fluid,  was  knoAvn  as  early  as  the  8th  century,  and  in  the  13th  century 
the  alchemists  succeeded  in  removing  the  water  from  the  "  spirits  of 
wine,"  thus  obtaining  absolute  alcohol.  It  was  not,  however,  until 
about  1600  that  Van  Helmont  showed  that  the  gas  given  off  in  fermen- 
tation was  the  same  gas  as  Avas  obtained  by  the  combustion  of  charcoal, 
or  Avhat  Ave  noAv  term  carbonic  acid.  Then,  it  Avas  ascertained  that  the 
production  of  the  alcohol  and  carbonic  acid  AA^as  at  the  expense  of  the 
sugar  in  the  fluid ;  and  Lavoisier  attempted  to  strike  a  balance  betAveen 
the  amount  of  sugar  at  the  beginning  of  the  process  and  the  amount  of 
alcohol  and  carbonic  acid  at  its  close.  As  AA'as  to  be  expected,  LaA^oisier 
always  found  that  he  could  not  account  for  the  Avhole  of  the  sugar, 
because  he  did  not  knoAV  all  the  substances  formed  in  the  alcoholic 
fermentation,  although  he  erroneously  suj^posed  acetic  acid  to  be  one  of 
them.  Gay-Lussac  repeated  these  quantitative  experiments  and  came 
nearer  to  the  truth,  but  still  there  AA'as  a  discrepancy.  In  1847,  Schmidt, 
of  Dorpat,  shoAved  that  succinic  acid  and  glycerine  Avere  formed  ;  and, 
at  last,  Pasteur  established  that,  from  100  parts  of  cane  sugar,  equal  to 
105-4  of  grape  sugar,  there  Avere  formed  51*1  of  alcohol,  49-4  of  car- 
bonic acid,  "7  of  succinic  acid,  3*2  of  glycerine — in  all,  104'4 — and  he 
supposed  that  about  1  per  cent.  AA^as  taken  up  by  the  yeast  itself.  Even 
in  this  case  the  balance  is  not  correct;  but,  making  alloAvance  for  errors 
of  experiment,  it  is  sufficiently  near  to  shoAv  that  in  the  process  of  fer- 
mentation the  sugar  is  resoH'ed  into  a  number  of  chemical  substances. 
Such,  then,  is  Avhat  Ave  may  term  the  chemical  side  of  the  problem. 
Even  the  early  observers  could  not  fail  in  observing  that,  if  pure 


FERMENT  A  TION.  \  77 

grape  jiiice  is  boiled  and  kept  in  a  well-corked  bottle  to  exclude  the 
air,  fermentation  does  not  take  place.  Pure  solutions  of  cane  sugar  or 
of  grape  sugar  do  not  ferment  under  these  circumstances,  whilst 
impure,  unfiltered,  unboiled  solutions  readily  undergo  fermentation. 
This  disposes  of  the  conjecture  one  might  make,  that  the  atoms  forming 
the  sugar  are  simply  rearranged  so  as  to  produce  alcohol,  carbonic  acid, 
glycerine,  succinic  acid,  and  other  bodies,  just  as  the  atoms  of  cyanate 
of  ammonium,  NH^CNO,  may  be  rearranged  so  as  to  form  urea, 
CH^NoO.  Something  evidently  must  be  added  to  the  grape  juice  to 
cause  fermentation.  As  well  put  by  Professor  W.  Dittmar,i  an  analysis 
of  yeast  does  not  reveal  the  existence  of  any  substance  capable  of  effect- 
ing this  remarkable  transformation.  Take  the  most  recent  analysis  of 
yeast  by  Schiitzenberger.  An  extract  of  yeast  in  boiling  water  showed 
— (1)  a  considerable  quantity  of  phosphates  ;  (2)  a  large  quantity  of 
gum  (arabin)  convertible  by  nitric  acid  into  mucic  acid ;  (3)  leucin  and 
tyrosin,  to  the  former  of  which  a  sulphiuretted  compound  obstinately 
adhered ;  (4)  carnin,  xanthin,  guanin,  hypoxanthin,  and  sarcin.  It  is 
remarkable  how  similar  this  analysis  is  to  that  of  an  animal  substance, 
l)ut  none  of  these  chemical  compounds  can  be  supposed  to  effect  the 
transformation  of  sugar  into  those  formed  in  the  alcoholic  fermentation. 
By  slow  stages,  however,  the  part  played  by  the  yeast  came  to  be 
recognized.  So  long  ago  as  1680,  Leeuwenhoek,  with  his  simple 
microscope,  saw  that  in  fermenting  fluids  there  were  minute  globular 
or  ovoid  j^articles.  This  was  the  first  obserA^ation  of  the  yeast-cells, 
and  for  many  years  they  received  little  or  no  attention.  In  1838, 
however,  Schwann  and  Cagniarcl  de  la  Tour  demonstrated  the  vegetable 
nature  of  these  yeast  cells,  and  showed  that  they  grew  and  multiplied 
in  saccharine  solutions,  and  for  the  first  time  it  was  asserted  that  fer- 
mentation in  some  way  depended  on  the  action  of  living  things. 

Previous  to  1838,  Berzelius  put  forward  the  theory  that  the  action  of 
the  yeast  is  what  is  called  catalytic  (Kara,  Averts,  separation),  or  a  mere 
action  of  presence,  similar  to  that  of  platinum-black  on  peroxide  of 
hydrogen,  causing  the  latter  to  give  up  an  atom  of  oxygen.  This  theory 
Aras  no  explanation.  Another  view,  first  proposed  by  Liebig  in  1848,  is 
that  there  is  no  necessary  connection  between  the  fermentive  process  and 
the  development  of  living  organisms,  and  that  the  organisms  may  simply 
produce  a  substance,  the  molecular  vibration  of  which  may  cause  a 
rearrangement  of  the  atoms  of  the  substance  undergoing  fermentation. 
This  is  a  modification  of  the  mechanical  theory  of  Berzelius  above 
described.  The  spHtting  up  of  sugar  into  carbonic  acid  and  alcohol,  by 
the  action  of  the  yeast  plant,  he  places  side  by  side  with  the  decompos- 

^W.  Dittmar,  article  "Fermentation"  in  the  Encydoi).  Br'dami.  9tli  edit. 
I.  BI 


]78  THE  CHEMISTRY  OF  THE  BODY. 

itiou  of  anhydrous  acetic  acid  into  acetone  and  carbon  dioxide  (a  change 
brought  about  by  heat),  and  with  the  change  of  an  aqueous  solution  of 
cyanogen  gas  into  oxaniide,  which  is  brought  about  by  the  action  of  the 
merest  trace  of  aldehyde.  Just  as  the  vibration  produced  by  the  alde- 
hyde determines  the  rearrangement  of  the  atoms  of  cyanogen  and  water 
so  as  to  constitute  oxamide,  so  Liebig  regards  the  rearrangement  of  the 
atoms  of  sugar  as  the  result  of  a  vibration  produced  by  the  chemical 
changes  which  take  place  in  some  unstable  substance  produced  by  the 
yeast-plant.  The  growth  of  the  yeast-plant  is,  according  to  this  idea, 
indirectly  connected  with  the  process  of  fermentation.  "  It  is  possible," 
he  says,  "that  the  physiological  process  stands  in  no  other  relation  to  the 
process  of  fermentation  than  that,  by  means  of  it,  a  substance  is  formed 
in  the  living  cell,  Avhich,  by  an  action  peculiar  to  it — resembling  that  of 
emulsin  on  salicin  or  amygdalin — determines  the  decomposition  of  sugar 
and  other  organic  molecules.  In  such  a  case,  the  physiological  action 
would  be  necessary  for  the  production  of  this  substance,  but  would  be 
other'snse  unconnected  with  the  fermentation  properly  so  called."  ^ 

For  many  years  this  theory  held  its  ground  owing  to  the  prestige  of 
its  illustrious  author,  and  fermentation  was  held  to  be  largely  a  chemical 
process.  But  facts  came  to  light  that  again  concentrated  the  attention 
of  men  of  science  on  its  biological  aspect. 

It  had  been  shown  by  Gay-Lussac  that  clean  grapes  or  boiled  grajje 
juice  introduced  into  the  Torricellian  vacuum  of  a  barometer  tube  kept 
free  from  fermentation  for  any  length  of  time,  but  that  if  a  single  bubble 
of  air  Avere  admitted  fermentation  soon  appeared.  Years  afterwards, 
in  1838,  in  his  celebrated  experimental  inquiry,  SchAvann  repeated  Gay- 
Lussac's  experiment,  and  shoAved  that  if  the  air  bubble  Avere  admitted  to 
the  vacuum  through  a  red-hot  tube  then  fermentation  did  not  occur. 
Clearly  then  it  AA^as  something  in  the  air  that  caused  fermentation,  and 
this  something  Avas  destroyed  by  heat.  Further,  it  was  noticed  from 
time  to  time  by  many  observers  that  active  fermentation  Avas  ahvays 
accompanied  by  an  apparent  groAA'th  of  the  yeast,  and  also  that  the  pro- 
cess could  be  influenced  by  various  physical  and  chemical  conditions. 
Thus  a  temperature  of  from  20"  to  24"  C.  Avas  most  favourable  to  it ;  it 
Avas  arrested  at  60°  C,  and  boiling  destroyed  the  poAver  of  fermentation. 
On  the  other  hand,  it  Avas  arrested  by  freezing,  but  on  careful  thaAving, 
the  process  Avas  resumed.  Chemical  substances,  also,  such  as  alcohol, 
bichloride  of  mercury,  sulphuric  acid,  and  sulphurous  acid,  impeded  or 
arrested  it. 

The  next  great  step  was  made  Avhen  SchAvann  endeavoured  to  identify 

^  Article  "  Fermentation,"  in  Supplement  to  Watt's  Dictionary  of  Chemistry, 
Tol.  vi.  p.  612. 


FERMENT  A  TIO  N.  179 

the  processes  of  fermentation  and  putrefaction.  In  the  17th  century, 
Stahl,  with  that  curious  insight  that  gives  his  -writings  almost  a  pro- 
phetic character,  said  that  fermentation  and  putrefaction  were  essentially 
the  same,  and  he  explained  both  by  disturbances  in  the  molecules  of  the 
fermentive  or  putrefactive  body.  Schwann,  however,  full  of  views  about 
the  origin  of  the  tissues  from  cells,  and  of  speculations  as  to  spontaneous 
generation,  investigated  putrefactive  fluids  with  a  knowledge  of  the 
existence  in  these  fluids  of  vibrios  and  other  living  organisms.  He  found 
that  if  a  putrescible  fluid  is  boiled  and  excluded  from  the  air  no  putre- 
faction occurs,  but  that  if  air  is  subsequently  admitted,  putrefactive 
changes  soon  ensue.  Obviously  then  the  air  has  to  do  with  putrefaction. 
But  if  the  air  were  previously  passed  through  red-hot  tubes  there  was 
then  no  putrefaction,  and  this  warranted  the  conclusion  that  it  was  not 
the  air  itself  but  something  in  the  air  that  caused  putrefaction.  He  also 
made  the  important  observation  that  the  chemical  substances  affecting 
fermentation  and  putrefaction  varied  in  their  mode  or  degree  of  action. 
Thus  white  arsenic  and  corrosive  sublimate,  which  poison  both  plants 
and  animals,  stop  both  putrefaction  and  fermentation,  whilst  nux  vomica, 
which  poisons  animals  but  not  plants,  prevents  putrefaction,  whilst  it 
does  not  arrest  the  -vdnous  fermentation.  These  statements  require 
modification  in  the  light  of  more  modern  inc|uiries,  but  they  merit 
attention  here  as  being  an  important  contribution  to  knoAvledge. 

Schwann's  conclusions  were  supported  by  many  important  experi- 
mental inquiries.  Von  Helmholtz  showed  that  the  oxygen  produced  by 
electrolysis  in  a  sealed  up  fermentable  fluid  did  not  cause  fermentation. 
He  also  performed  a  remarkable  experiment  in  which  he  placed  a  bladder 
full  of  boiled  grape  juice  in  a  vat  of  fermenting  juice  and  found  that  the 
fluid  in  the  bladder  did  not  ferment.  Thus  the  cause  of  fermentation 
could  not  pass  through  the  wall  of  the  bladder.  Mitscherlich  showed 
that  when  in  a  tube  a  layer  of  fermentable  fluid  was  separated  from  a 
layer  of  yeast  by  a  septum  of  filter  paper  no  fermentation  occurred. 
Hoffmann  proved  that  a  layer  of  cotton  wool  had  the  same  effect,  and 
Schroeder  and  Dusch  made  the  important  demonstration  that,  if  a 
putrescible  fluid  be  boiled  in  a  flask  and  the  neck  of  the  flask  be  plugged 
with  cotton  wool  at  the  moment  the  flame  is  removed  from  underneath 
the  flask,  putrefaction  will  not  occur  in  the  fluid.  It  might  be  objected 
that  putrescible  fluid  will  keep  fresh  in  a  hermetically  sealed  flask  because 
no  air  has  been  admitted,  but  this  objection  will  not  hold  good  when 
applied  to  the  experiment  -with  the  plug  of  cotton  wool.  Here  evidently 
air,  but  filtered  air,  has  been  admitted,  and  still  putrefaction  does  not 
occur.  The  cotton  wool  has  sifted  from  the  air  the  bodies  that  cause 
putrefaction,  just  as  the  wall  of  the  bladder,  the  septum  of  filter  paper, 


180  THE  CHEMISTRY  OF  THE  BODY. 

or  the  layer  of  cotton  wool,  prevents  the  }):issage  of  the  yeast  cells  from  a 
fermenting  to  a  fermentable  fluid.  Even  if  the  neck  of  the  flask  be  long 
drawn  out  and  lient  here  and  there  in  a  zig-zag  fashion  Avithout  sealing 
up  the  tube,  a  j)utrescil')le  fluid  will  remain  free  from  putrefaction  in  the 
flask.  In  this  case  the  organisms  that  cause  putrefaction  are  caught  at 
the  bends  of  the  neck  of  the  flask.  The  conclusion  then  is  irresistible 
that  the  living  organisms  in  the  air  and  in  the  yeast  are  the  cause  of 
putrefaction  and  of  fermentation. 

Such  was  the  state  of  the  question  when,  in  1857,  Pasteur  began  those 
important  researches  Avhich,  continued  in  various  forms  up  to  the  present 
time  (1888),  have  revolutionized  this  department  of  science.  Pasteur, 
in  particular,  shoAved  that  each  kind  of  fermentation  was  connected  with 
the  growth  and  development  of  a  special  organism,  and  that  as  the  yeast 
cell  was  specially  the  cause  of  the  alcoholic  fermentation,  so  there  Avas 
another  organism  for  the  lactic  fermentation  by  Avhich  the  sugar  of  milk 
was  changed  into  lactic  acid,  and  a  third  which  efifected  the  transformation 
of  lactic  into  butyric  acid.  Further,  he  introduced  the  method  of  culti- 
A^ating  certain  organisms  in  fluids  specially  adapted  to  their  wants  and 
inimical  or  unsuitable  toother  organisms,  and  thus  by  repeated  cultivations 
he  demonstrated  that  it  A\^as  possible  to  obtain  a  fluid  containing  one 
organism,  the  physiological  properties  of  Avhich  might  then  be  examined. 
Thus  by  soAving  a  mixture  of  organisms,  a,  h,  c,  and  d,  in  a  sterilized 
fluid  suitable  specially  for  the  groAvth  of  a,  and  hj  repeating  this  process 
many  times  AAdth  the  fluid  of  successiA^e  cultivations,  a  fluid  is  obtained 
in  Avhich  only  the  organism  a  is  found,  the  others  having  perished  in 
the  struggle  for  existence  in  exceptional  conditions.  This  method  has 
been  of  the  greatest  importance  to  science,  and  like  maiij^  neAv  methods 
has  been  the  key  to  many  problems. 

It  AA^as  in  1864  that  Pasteur  made  the  important  observation  that  the 
ferment  causing  the  butyric  fermentation  is  capable  of  liAang  and  multi- 
plying in  a  fluid  containing  certain  mineral  matters,  along  Avith  sugar 
or  lactate  of  lime,  and  that  it  does  this  in  the  absence  of  free  oxygen  or 
of  free  air.  In  this  case  the  presence  of  oxygen  or  of  air  arrests  the 
fermentation,  for  if  the  air  be  again  excluded,  the  fermentation  Avill  be 
resumed.  This  led  to  the  investigation  of  the  behaviour  of  various  fer- 
mentive  organisms,  Avith  the  result  of  shoAving  that  the  same  rule  pre- 
vailed AAdth  many  (as  in  the  but3'ric  fermentation),  namely,  that  the  fermen- 
tation is  carried  on  most  efficiently  in  the  absence  of  free  air  or  free 
oxygen.  Further,  it  Avas  ascertained  that  most  fermentiA^e  organisms 
may  assume  tAA^o  conditions,  one  aerobic,  that  is,  liAdng  in  the  presence 
of  oxygen  or  of  air,  and  the  other  anaerobic,  that  is,  liAang  in  the  absence 
of  the  oxygen ;  and  it  is  Avhen  it  is  in  the  latter  condition,  the  anaerobic. 


FERMENT  A  TION.  1 81 

that  ail  organism  carries  on  the  work  of  fermentation.  If  the  organism 
receives  a  free  supply  of  oxygen  from  the  air,  it  consumes  it,  assimilates 
nutritious  matters,  and  takes  on  a  certain  habit  of  growth,  like  the  coloured 
moulds  found  on  the  surface  of  preserved  fruits  or  on  milk  exposed  to 
the  air.  On  the  other  hand,  if  there  is  a  limited  supply  of  oxygen,  or 
none  at  all,  the  organism  removes  oxygen  from  the  fermentable  matter 
and  thus  causes  fermentation.  The  curious  fact  that  these  lowly 
organisms  apparently  may  live  without  free  oxygen  is  no  exception  to 
the  general  law  that  all  living  things  require  this  gas,  but  they  have  a 
special  method  under  certain  circumstances  of  obtaining  it,  namely,  by 
the  decomposition  of  the  fermentable  matter.  Thus  Pasteur  is  justified 
in  the  aphorism,  "La  fermentation  est  la  vie  sans  air"  and  this  remark- 
able property  points  to  the  important  role  of  fermentations  in  many  of 
the  phenomena  of  the  living  body.  It  is  c|uite  true  that  the  actual 
removal  of  oxygen  from  sugar  by  the  action  of  the  yeast  has  not  been 
demonstrated,  and  that  the  explanation  is  thus  far  theoretical ;  but 
without  this  theory,  it  is  difficult  to  account  for  the  fact  that  some 
organisms  do  live  and  multiply  without  the  access  of  either  oxygen  or 
air.  A  few  flourish  best  with  less  oxygen  than  in  ordinary  atmospheric 
air.  Thus  Engelmann  showed  that  some  species  gather  close  to  a 
bubble  of  air,  whilst  others  keep  away  from  it  and  only  come  near  when 
the  bubble  has  lost  a  part  of  its  oxygen.  On  the  other  hand,  some, 
such  as  Bacterium  aceti,  require  oxygen,  and  are  truly  aerobiotic.  It 
would  appear  that  at  the  beginning  of  fermentation  oxygen  is  required, 
but  that  after  it  has  begun,  free  oxygen  may  or  may  not  be  requisite 
according  to  the  nature  of  the  organism  carrying  it  on. 

Thus,  after  many  vicissitudes,  the  vitalistic  theory  of  fermentation 
has  been  put  on  a  secure  footing.  True  ferments  in  the  shape  of  living 
organisms  have  been  found  for  the  lactic  fermentation,  resulting  in  the 
jiroduction  of  butyric  acid ;  for  the  viscous,  by  which  sugar  may  be 
changed  into  mannite ;  for  the  acetous,  by  which  sugar  may  pass 
through  alcohol  into  acetic  acid ;  for  the  conversion  of  urea  into  carbo- 
nate of  ammonia  in  decomposing  urine ;  and  for  the  phenomena  of 
putrefaction,  in  which,  by  the  action  of  iaderiumr-foTms,  albuminous  and 
other  matters  are  changed  into  simpler  bodies.  It  is  to  be  noted,  how- 
ever, that  while  each  fermentation  is  accompanied  by  the  development 
of  a  special  organism,  the  same  substance,  such  as  alcohol,  may  be  one 
of  the  products  of  different  fermentations. 

It  has  been  urged  by  some  that  the  multiplication  of  organisms  in  a 
fermenting  fluid  or  in  a  putrefactive  fluid  is  the  consequence  and  not 
the  cause  of  the  fermentation  or  putrefaction.  In  the  case  of  the 
alcoholic  fermentation,   this  is  disproved  by  the  experiments  of  Von 


182  THE  CHEMISTRY  OF  THE  BODY. 

Helmholtz,  INIitsflierlicb,  and  others,  -\vhicla  showed  that  if  the  yeast  cells 
were  prevented  from  passing  into  a  fermcntahle  fluid  by  the  interposition 
of  an  organic  membrane,  fermentation  did  not  ensue.  Further,  as 
shoArn  by  Chauveau,  the  properties  of  vaccine  lymph  are  due  to  the 
small  oi'ganic  particles  in  the  fluid,  and  not  to  anything  in  the  fluid 
itself;  and  it  has  been  found  possible  to  sterilize  various  fluids,  that  is, 
remove  from  them  organisms  cajjable  of  causing  fermentation,  by  passing 
the  fluids  through  thick  septa  of  finely  porous  substances.  A  striking 
corroboration  of  the  view  that  the  organisms  themselves  are  absohitely 
necessary  we  have  in  the  fact  that  if  the  fluid  containing  a  cultivation 
of  a  bacillus  believed  to  be  the  cause  of  splenic  fever  be  inoculated  into 
an  animal,  it  Avill  die  of  the  disease,  but  this  result  does  not  follow  if  the 
inoculated  fluid  has  been  pre^^ously  elaborately  filtered  so  as  to  remove 
the  bacillus. 

If  then  the  organisms  are  the  cause  of  the  fermentations,  how  do  they 
act  1  Do  they  live  on  the  fermentable  matter  and  oxygen,  and  are  the 
substances  Ave  call  the  products  of  the  fermentation  to  be  regarded  in 
the  light  of  excreted  or  Avaste  matters  1  Or,  do  the  organisms,  as  held 
by  Berthelot,  Fremy,  Hoppe-Seyler,  and  others,  produce  a  kind  of 
ferment  Avhich  in  turn  acts  on  the  fermentable  matter?  There  are 
reasons  for  holding  that  the  latter  AdeAv  is  not  far  from  the  truth.  It  is 
quite  true  that  no  substance  has  yet  been  separated  from  yeast  capable 
of  causing  the  alcoholic  fermentation  other  than  the  j^east  cell ;  but 
Berthelot  has  obtained  from  yeast  a  sohxble  ferment  capable  of  changing 
starch  and  cane  sugar  into  glucose.  Further,  as  Avill  presently  be  seen, 
there  are  many  soluble  ferments  kuoAvn  to  chemists,  but  these  are  all 
formed  in  the  first  instance  in  animal  or  vegetable  cells  that  may  be 
considered  to  be  the  analogues  of  the  organized  cells  capable  of  causing 
fermentation. 

Hoppe-Seyler  has  AAdth  great  force  pointed  out  that  the  action  of 
the  fermenting  matter  may  not  be  a  direct  oxidation,  but  rather  a 
reduction.  Thus,  in  the  lactic  and  alcoholic  fermentations  and  in  putre- 
faction there  is  the  liberation  of  hydrogen,  and  this  nascent  hydrogen 
may  seize  hold  of  an  atom  of  oxygen  from  ordinary  oxygen,  Og,  to  form 
water,  Ho  +  Og  =  H^O  +  0.  The  nascent  oxygen  thus  liberated  at  once 
attacks  any  oxidizable  matters  present,  or  it  may  unite  Avith  more  free 
hydrogen  to  form  AA^ater,  or  it  may  unite  Avith  a  molecule  of  ordinary 

oxygen,  Og,  to  form  a  molecule  of  ozone,  — -  ^    .    Thus  the  liberation  of 

hydrogen  may  be  the  cause  of  active  oxidations.  On  the  other  hand, 
suppose  no  free  oxygen  is  present,  then  the  hydrogen  liberated  attacks 
organic  substances,  reducing  them.     In  this  case  the  phenomena  are  not 


FERMENTATION,  188 

those  of  oxidation,  but  of  reduction,  and  we  see  how  in  fermentations 
and  putrefactions  there  may  be  either  oxidations  or  reductions  according 
to  the  presence  or  absence  of  oxygen.  Thus  in  putrefying  fluids  oxida- 
tions may  be  going  on  in  the  upper  layers  where  there  is  abundance  of 
oxygen,  and  reductions  in  the  lower  layers  where  the  oxygen  is  deficient 
or  absent. 

This  explanation  throAvs  some  light  on  the  phenomena  of  so-called 
oxidations  occurring  in  the  tissues.  It  may  be  supposed  that  some  of 
the  molecular  changes  concerned  in  the  nutrition  of  living  tissues  are 
similar  to  those  of  fermentations  in  the  absence  of  an  abundant  supply 
of  oxygen.  In  these  circumstances,  the  hydrogen  set  free  in  turn  liber- 
ates nascent  oxygen,  which  then  attacks  oxidizable  matter.  Thus, 
according  to  Hopj^e-Seyler,  supposing  the  oxidizable  matter  to  be  repre- 
sented by  n,  the  changes  would  be  represented  by  the  equation — 

HH  +  O2  +  %  =  H2O  -(-  On. 

It  will  be  observed  also  that  this  is  equivalent  to  a  dehydration. 

Ferments  may  be  classified  under  three  divisions — (1)  the  soluble 
ferments  ;  (2)  the  organized  ferments  ;  and  (3)  according  to  the  nature 
of  the  chemical  changes  they  are  capable  of  exciting. 

(1)  The  Soluble  Ferments. 

These  are  substances  produced  in  the  interior  of  animal  or  vegetable 
cells,  and  when  obtained  as  free  from  extraneous  organic  matter  as 
possible,  they  are  solid,  amorphous,  colourless,  tasteless  substances, 
soluble  in  Avater,  and  precipitated  from  their  aqueous  solutions  by 
alcohol,  and  the  acetate  of  lead.  Chemically,  they  resemble  the  deriva- 
tives of  albuminates,  but  they  contain  no  sulphur.  Their  chemical 
constitution  is  unknown.  The  following  are  a  few  examples  of  fermen- 
tive  processes — 

1.  The  conversion  of  starch  into  dextrin  and  glucose,  produced  by 
the  action  of  the  diastase  of  malt,  of  ptyalin  in  saliva,  of  a  ferment  in 
the  pancreatic  juice,  and  of  all  albuminous  matters  in  a  state  of  decom- 
position— 

4(06HioO,)     +     3H,0     =     CgHioOg     +     ZC,B.^^O,. 

Starch.  Dextrin.  Dextrose. 

or, 

'(a)     3(C6HioOg)     +     H2O     =     CiaH^oOn     +     CgHioOg. 

Starch.  Maltose.  Dextrin. 

(h)  2(C6Hio05)     +     H.3O     =     Ci^K^On. 

Dextrin.  Inverted  siigar. 

2.  The  transformation  of  cane  sugar  into  inverted  suoar,  which  is  a 


184  THE  CHEMISTRY  OF  THE  BODY. 

mixture  of  dextrose  and  Isevulose,  and  into  glucose,  accomplished  by 

a  ferment  in  the  intestinal  juice,  and  by  a  ferment  in  yeast — 

Ci2H.«0ii     +     H.O     =     CoHiaOfi     +     CgHiaOfi. 
Cane  sugar.  Dextrose.  Lajvulose. 

3.  The  conversion  of  glucosides,  such  as  amygdalin,  into  glucose  and 
various  compounds,  accomplished  by  synaptase  or  emulsin — 

CooH,7NO,i     +     2H2O     ^     2C6H,.A     +     QHgO.NHC. 

Amygdalin.  Glucose.  Oil  of  bitter  almonds. 

CisHigO,     +     H.O     =     CoHi.Og     +     CVHgOo. 
Salicin.  Glucose.  Saligenin. 

4-.  The  conversion  of  glucose  into  glycerine  and  mannite — 

CgHj.iOg     +     H^     =     CeH,40e. 

Glucose.  Mannite. 

5.  The  conversion  of  glycerine  and  of  mannite  into  alcohol  T)y  the 
action  of  nitrogenous  organic  matter  in  a  state  of  decom})Osition. 
(Berthelot.) 

6.  The  splitting  up  of  fats  into  fatty  acids  and  glycerine  by  the  action 
of  a  ferment  in  the  pancreatic  juice — 

C.VH104O6     +     m.p     =     3(Ci8H,,0,)     +     C3H8O3. 

Olein.  Oleic  acid.  Glycei-ine. 

7.  The  transformation  of  albuminates  into  peptones  by  the  action  of 
pepsin,  the  ferment  of  the  gastric  juice,  and  by  a  ferment  in  the  pan- 
creatic and  intestinal  juices. 

The  following  are  examples  of  the  chemical  changes  effected  in  these 
processes  of  fermentation — 

1.  Simple  isomeric  transformations,  as  in  the  conversion  of  starch 
into  dextrin  and  sugar. 

2.  Hydrations,  as  in  the  conversion  of  cane  sugar  into  glucose. 

3.  Synthetic  processes,  as  in  the  fermentation  of  glucosides. 

4.  The  separation  of  water,  and  a  change  in  the  molecular  condition 
of  the  remainder,  as  in  the  conversion  of  albuminates  into  peptones 
{hydrohjt  ic  ferments). 

It  is  to  be  noted  that,  in  many  instances,  chemical  changes,  similai- 
to  those  produced  by  soluble  ferments,  may  be  effected  by  the  action  of 
heat  and  of  the  mineral  acids.  Thus,  sulphuric  and  hydrochloric  acids 
effect  a  hydration  and  change  cane  sugar  into  dextrose  and  Itevulose, 
milk  sugar  into  galactose,  and  starch  into  dextrin  and  dextrose  accord- 
ing to  the  above  equations. 

Many  of  these  ferments  may  be  arranged  under  the  following- 
physiological  classification,  which  is  also  practical — 

I.   Proteolytic- — those  changing  albuminous  matter  into  peptones  (acid 


FERMENTATION.  185 

digestion  by  pepsin  of  gastric  juice)  or  into  tryptones  and  then  into  leucin, 
tyrosin,  etc.  (alkaline  digestion  l:'y  tripsin  of  pancreatic  juice). 

II.  Aniylolytic — those  changing  starch  into  glucose  with  absorption  of 
water,  such  as  the  ptyalin  of  saliva,  a  ferment  in  the  pancreatic  juice, 
and  a  ferment  in  the  liver  and  in  many  tissues. 

III.  Steatolytic — those  decomposing  fats  with  water,  as  a  ferment  in 
the  pancreatic  juice. 

IV.  Inversive — converting  cane  sugar  into  inverted  sugar.  Such  a 
ferment  exists  in  the  intestinal  juice,  possibly  to  a  small  extent  in  saliva 
and  in  hepatic  cells. 

V.  Blood  ferment — causing  union  of  the  elements  that  form  the  fibrin 
of  blood  clot. 

Ferments  of  this  class  are  the  principal  agents  in  the  chemical 
transformation  of  food  in  the  process  of  digestion,  and  in  all  probability 
processes  of  a  fermentive  character  also  occur  in  certain  organs,  as  in 
the  liver. 

(2)  The  Organized  Ferments. 

These  are  living  organisms,  the  type  of  which  is  the  unicellular 
plant  found  in  yeast,  known  as  Saccharomycetes  cerevisice,  and  including 
such  organisms  as  many  forms  of  fungi,  vibrios,  and  bacteria. 

1.  Soluble  ferments  usually  produce,  as  the  result  of  their  action,  not 
more  than  one  or  two  substances,  but  the  organized  ferments,  as  a  rule, 
produce  several  substances.  Thus  glucose,  in  the  presence  of  yeast  not 
only  may  yield  carbonic  acid  and  alcohol  but  also  glycerine,'  succinic 
acid,  acetic  acid,  fatty  matter,  a  nitrogenous  matter,  and  other  products. 

2.  Organized  ferments,  as  already  explained,  do  not  absolutely  re- 
quire the  presence  of  the  oxygen  of  the  air,  as  they  have  the  power  of 
obtaining  oxygen  from  fermentescible  matter  itself  In  certain  cases  it 
would  even  appear  that  excess  of  oxygen  arrests  fermentation.  Pasteur 
has  shown  that  vibrios  are  killed  by  a  strong  current  of  oxygen  passed 
through  the  fluid  containing  them,  and  Paul  Bert  has  found  fermentation 
to  go  on  much  more  slowly  under  a  pressure  of  five  atmospheres  of  pure 
■oxygen. 

3.  As  examples  of  the  fermentations  excited  by  such  organisms,  we 
may  consider  the  following — 

a.  Alcoholic — - 

CgHi-A     +     H2O     =     2C0o     +     2(C2H60)     +     H2O. 

Grape  sugar.  Alcohol. 

b.  Lactic  acid — 

C12H2A1     +     H,0     =     4(C3H603). 

Milk  sugar.  Lactic  acid. 


186  THE  CHEMISTRY  OF  THE  BODY. 

c.  Butyric  acid — 

2(C3H603)     -     C^HgO,     +     2C0,     +     2H,. 

Lactic  ficid.  Butyric  acid. 

d.  Acetous — 

CgHeO     +     0     =     C2H4O     +     HoO;    then  C0H4O     +     0     =     aH402. 
-^cohol.  Aldehyde.  Aldehyde.  Acetic  acid. 

e.  Putrefaction — This  cannot  be  represented  by  an  equation  but 
albuminous  and  fatty  matters  are  changed  into  leucin,  tyrosin,  fatt}^ 
acids,  glycerine,  ammonia,  sulphuretted  hydrogen,  Avater,  hydrogen,  and 
possibly  nitrogen. 

(3)  Classification  of  Ferments  according  to  tue  Nature  of  the  Chemical 
Changes  they  Produce. 

Hoppe-Seyler^  has  given  an  important  classification  of  ferments  which 
is  in  the  main  chemical  in  its  character,  but  it  merits  special  attention 
because  it  illustrates  the  probable  action  of  many  fermentive  substances 
whether  soluble  ferments  or  organized  ferments. 

I.  The  conversion  of  anhydrides  into  hydrates — 

A.  Ferments  acting  like  weak  mineral  acids  at  the  temperature  of 
boiling  water  (100°  C). 

1.  Conversion  of  starch  or  glycogen  into  dextrin  and  glucose — 

4(CeHio05)     +     SHoO     =     CeHjoOg     +     SlCgHi-A)- 
starch.  Dextrin.  Glucose. 

2.  Conversion  of  cane  sugar  into  glucose  and  Isevulose  (fruit  sugar) — 

CjoH2,0ii     +     HoO     =     CgHiA     +     CfiHiaOfi. 
Cane  sugar.  Glucose.  Lasvulosc. 

3.  Conversion  of  a  benzol-giucoside  into  sugar  and  a  benzol  deriva- 

tive by  the  action  of  emulsin — 

CisHjgO,  +   H,0     =     CeHiA  +   C«H,{g|2'^^ 
Salicin.  Sugar.  Saligenin. 

Ci3H,eO,  +   H,0     =     CfiHi^Oe  +   CeH.jgg^ 
Hulicin.  Sugar.  Palicylaldehyde. 

C,3Hi,03  +  H,0     =     CgHi^O^  +  QH,{gg-  0^ 

Glucoside  of  sail-  Sugar.  Salicylic  acid. 

cylic  acid. 

C25H34O14  +   2(3^0)     =     '2[C,n,^,)   +    CeH,{g|  +   CeH.jggHa 

ArbutiD.2  Sugar.  Hydrochinon.  llethylhydrochinoii. 

C20H07NO11   +  2(H„0)     =     2(C6HiA)   +   CgHg.COH.CHN 
Amygdalin.  Sugar.  Oil  of  bitter  almonds. 

^  Physiologisclie  Chemie,  1877,  p.  116  et  seq. 

^  Arbutin,  a  crystalline  suljstance  in  leaves  of  red  bearberry  (Arctostaphylos 
uva  ursi). 


FERMENTATION.  187 

CisHjoOg      +   H,0     =        CeHioOg    +   CioHuOs .  OH 

Coniferin.i-  Sugar.  Conifer-alcohol. 

C14H18O9      +  HoO     =        CfiHisOe    +   CgHgO^ 
Gluooside  of  vanillic  Sugar.  Vanillic  acid, 

acid. 2 

CgiHg^Oig  +     2(H.,0)     =     2(C6Hi208)   +   CigHi.Og 
Dapliinin.3  Sugar. 

C3iH5oOi,*+  5HoO  =  SlCfiHiA)  +  Ci3H.3,03 
Cg^HggOifi  +  5H.0  =  3(C6Hi.,06)  +  C16H30O3 
Jalapin.i  Sugar. 

■4.  Decomposition  of  a  sulphur  compound  into  sugar,  sulphuric  acid 
and  oil  of  mustard  through  myrosin — 

CioHigNSoOioK     =     CeHi.,06     +     KHSO4     +     C4H5NS 
Myronate  of  potassium. 5  Sugar.  Sulphate  of        Oil  of  mustard. 

potassium. 

CgoH^NoSoOn     =     CeHiaOy     +     CieHo.N .  SO^H     +      CgH.ONS 
White  mustard.  Sugar. 

B.  Ferments  acting  like  caustic  alkalies  at  a  higher  temperature. 

1.  Decomposition  of  ethers  and  of  the  fats  into  an  alcohol  and  fatty 
•   acid. 

2.  Decomj)osition  of  amides  with  absorption  of  water — 

CH^N.O         +         HoO         =         (NHJ.COs 
Urea.  Carbonate  of  ammonia. 

C9H9NO3     +     H.,0     =     C.,HgN02     +     C^HgO., 

Hippuric  acid.  Glycocoll.  Benzoic  acid. 

CagH^gNSO,     +     HoO     =     C0H7NSO3     +     CojH^oOg 

Tauro-cholic  acid.  Taurin.  Cholalic  acid. 

II.  Ferments  causing  the  transference  of  the  oxygen  from  the  hydro- 
gen atom  to  the  carbon  atom. 

1.  The  lactic  fermentation.  Here  one  molecule  of  milk  sugar,  with 
the  addition  of  a  molecule  of  water,  is  changed  into  two  mole- 
cules of  sugar  (dextrose  and  Isevulose),  which  in  turn  become 
four  molecules  of  lactic  acid. 
■  2.  The  alcoholic  fermentation.  The  transference  of  0  from  H  to  C 
is  thus  shoAvn — 

CH.,  .OH  CO  .  (0H)o 

CH  .  OH  CHoOH  )  , ,    ,    , 

CH  .  OH  +  2HoO     =    CH3        /-'^^co^o^- 
CH  .  OH  '  CH3         \  A  icohol 

CH  .  OH  CHoOH   S  Alcohol. 

COH  CO(OH)o 

Glucose. 
'  Coniferin,  a  glucoside  in  the  cambium  of  coniferous  woods,  Ahks  exceUa,  Larix 
Europoea,  etc. 

2  Vanillin,  neutral  odoriferous  principle  of  vanilla,  fruit  of  Vanilla  planifolia. 

3  Dapliinin,   a  crystallizable  glucoside  in  Daphne  alpina  and  other  species  of 
Daphne.     *  Convolvulin,  a  resin  from  Convolvulus  schiedeanus. 

*  Jalapin,  a  resin  obtained  from  scammony  resin,  yielded  by  Ipomcea  orizabensis. 
s  A  salt  in  the  seed  of  black  mustard. 


188 


THE  CHEMISTRY  OF  THE  BODY. 


3.  Putrefaction.     The  following  are  examples — 


(CHO.,)oCa       + 
Formate  of  lime. 

H.,0        n: 

CaCOg   +   CO.,     +     -211, 
Carbonate  of  lime. 

(C-HsOaJoCa     + 

Acetate  of  lime. 

H.O     = 

CaCOg    +    CO.^      +      2CH4 

Carbonate                          Jlarsh  gas. 
of  lime. 

"{CgHioOg)     + 
Cellulose. 

nCK-fi) 

=     3»(C0,)     +     3«(CHJ 
Marsh  gas. 

Lactate  of  lime. 

CaCO,, 

Carbonate 
of  lime. 

+     3C0.,     +     4H,     +     Ca(C4HA)2 
Butyrate  of  lime 

(4)  The  Nature  of  the  Organized  ^'ebments. 

These  organisms  belong  to  the  group  of  bodies  to  which  the  name 
of  Schizomycetes  was  given  by  Naegeli  in  1857,  and  they  include  such  as 

cl 


Fig.  66.— Typical  forms  of  Schizomycetes  (after  Zopf). 
a,  micrococcus;  6,  macrococcus,  or  "  monas" ;  c,  bac- 
terium ;  d,  bacillus  ;  e,  chlostridium  ;  /,  monas  Okenii ;  (?, 
leptothrix ;  h,  i,  vibrio ;  le,  spirillum  ;  I,  spirulina  (a 
form  of  Beggiatoa  alba);  m,  spiromonas  ;  «,  spirochaBte  ;  o, 
cladothrix.  The  gi-anules  in  h,  f,  and  e  are  particles  of 
sulphur. 

are  often  termed  bacteria,  bacilli,  micrococci,  microphytes,    microbes, 
etc.     They  are  minute  unicellular  bodies  of  the  nature  of  saprophytic 


FERMENT  A  TION.  189 

or  parasitic  schizophyta,  devoid  of  chlorophyll,  and  multiplying  usually 
by  fission,  and  in  some  by  a  process  of  spore-formation.  They  vary  in 
size  from  -001  to  '005  mm.  in  length.  The  general  appearance  of  the 
typical  forms  of  these  organisms  is  thus  given  by  Professor  Marshall 
AVardi  (Fig.  66). 

The  form  may  be  one  of  the  foUowdng — 

(1)  Globular  or  spheroidal,  usually  termed  micrococcus,  or,  if  larger, 
macrococcus  or  monas. 

(2)  Ilocl-like,  cylindrical  cells,  three  or  four  times  as  long  as  broad, 
hacterkmi,  when  the  rods  are  short,  or  with  rounded  ends,  or  bacillus,  when 
the  rods  are  longer  and  usually  sharply  cut  off  at  the  end. 

(3)  Filaments,  consisting  of  single  elongated  filaments,  or  of  several 
much  elongated  cells  that  have  remained  attached  after  di\dsion ;  such 
are  seen  in  leptothrix. 

(4)  Spiral  forms— 'li  the  sinuosity  be  slight,  the  body  is  a  vibrio,  and 
if  more  cork-screw  like,  a  spirillum. 

(5)  Plates  or  tablets,  irregular  branching  groups  of  cells,  which,  by 
successive  divisions  both  longitudinal  and  transverse,  give  rise  to  little 
groups  of  square-shaped  cells  lying  in  groups  of  four,  six,  or  eight,  as  in 
sarcina. 

Some  schizomycetes  shoAv  pleomorphism,  that  is  to  say  the  same  organ- 
ism at  one  stage  of  its  life,  may  appear  in  the  form  of  a  micrococcus,  at 
a  later,  of  a  bacterium,  and  afterwards,  as  a  filament  or  leptothrix.  An 
example  of  such  an  organism  is  Cladothrix  dichotoina,^  and  the  special 
forms  have  been  regarded  erroneously  as  different  species  of  schizomy- 
cetes. On  the  other  hand,  many  of  these  organisms  maintain  the  same 
form,  generation  after  generation. 

Schizomycetes  are  found  practically  almost  everywhere,  and  if  any 
putrescible  fluid  is  exposed  to  the  air  for  some  hours,  at  ordinary  tem- 
peratures, it  soon  swarms  with  micrococci  and  bacteria.  They  also 
abound  in  many  animal  fluids  in  the  living  body  under  certain 
conditions  of  disease,  and  some  representatives  may  be  found  in  small 
numbers  in  the  tissues  even  in  a  state  of  health.  In  the  alimentary 
canal,  except  where  the  secretions  are  highly  acid,  they  are  also 
plentiful. 

Each  schizomycete  consists  primarily  of  a  minute  cell,  never  nucleated, 
formed  of  a  mass  of  "  homogeneous  or  slightly  granular  protoplasm 
with  a  pearl-like  lustre,  and  without  vacuoles ;  this  is  enveloped  by  a 
membranous   envelope   Avhich   is    so  delicate  as  to   be   scarcely    per- 

1  Marshall  Ward,  article  "Schizomycetes,"  in  Ennjdop.  Britannka,  vol.  xxi. 
p.  399. 

-  Figured  in  Marshall  Ward's  article.     (Fig.  16,  op.  cit. ) 


190 


THE  CHEMISTRY  OF  THE  BODY. 


ceptible."^  This  envelope  in  some  cases  consists  of  cellulose.  Coloured 
pigments  (red,  yellow,  green,  or  blue)  have  been  fo\ind  in  some 
organisms.  The  protoplasmic  matter  consists  of  a  colourless  substance 
named  mi/co-protein.  Starch  has  been  found  in  some  bacteria,  giving  a 
blue  colour  with  solutions  of  iodine.  Minute  crystals  of  sulphur  have 
been  found  in  filamentous  schizomycetes  (see  Fig.  QQ,  f),  and  oily  and 
fatty  matters  have  been  detected.  Sometimes,  after  these  bodies  have 
multiplied  by  transverse  fission  until  a  long  chain-like  structure  has 
been  formed,  the  chain  may  break  into  fragments  and  the  particles  thus 
set  free — bacteria,  bacilli,  or  micrococci — form  dense  swarms  which 
"  become  fixed  in  a  matrix  of  their  own  swollen  contiguous  cell  walls, 
and  pass  into  a  resting  state  as  a  so-called  zoogloea." .  They  become 
entangled  in  this  jelly-like  matrix,  and  the  zoogioeain  itself  may  take  on 
forms,  spherical,  ovoid,  or  filamentous,  peculiar  to  the  species.  By-and- 
bye,  the  organisms  in  the  zoogioea  may  become  active,  and,  scattering 
in  the  surrounding  medium,  begin  to  grow  and  multiply. 

The  multiplication  of  schizomycetes  by  spores  is  now  a  well-ascer- 
tained fact,  and  the  various  tyjjes  of  this  mode  of  development  are  shown 
in  Fia:.  67. 


K. 

\ 

0     ^ 

Oc 

'00°o 

0 

I 

A     A 

^  a 

c        6 

o 

a 

0 

0 
o 

0 

^ 

L 

i 

.^ 

H 

Fig.  67. — Types  of  spore-formation  in  schizo- 
mycetes. (After  Zopf.)  A,  various  stages  in 
the  development  of  the  endogenous  spores  in 
a  Clostridium  {haciUus),  the  small  letters  indi- 
cating the  order.  B,  endogenous  spores  of 
the  hay  bacillus.  C,  a  chain  of  cocci  of  Icu- 
<;onostoc)(i,esenfc/-ioic7t's, with  two  resting  spores, 
i.e.  arthrospores.  (After  Van  Tieghem.)  D, 
a  mobile  rodlet  with  one  ciliuni,  and  with  a 
spore  forming  inside.  E,  spore-formation  in 
(^t&ro-like(e),and  SpiriUum-W^e  (o,  h,  d)  schizo- 
mycetes. F,  long  rod-like  form  containing  a 
spore  (these  are  the  so-called  "  Kopfchcn- 
bacterien "  of  German  authors).  Gr,  Yibrio- 
form  with  spore.  (After  Prazmowski.)  H, 
Clostridium — one  cell  contains  two  spores. 
(Prazmowski.)  I,  Spirillum  containing  many 
spores — a,  which  are  liberated  at  b  by  the 
breaking  up  of  the  parent  cells.  K,  (Termina- 
tion of  the  spore  of  the  hay  bacillus  (Bacillus 
subtilis) — the  axis  of  growth  of  the  germinal 
rodlet  is  at  right  angles  to  the  long  axis  of  the 
spore.  L,  germination  of  the  spore  of  Clostri- 
dium butyricum — the  axis  of  gi'owth  coincides 
with  the  long  axis  of  the  spore. 


It  is  now  well  known  that  schizomycetes  are  found  in  the  blood, 
tissues,  and  organs  of  animals  and  of  man  suffei-ing  from  certain  specific 
diseases.       One   of   the    most    striking    instances    of    this    occurs    in 
^  Marshall  Ward,  op.  cil. 


FERMENT  A  TION. 


191 


splenic  fever,  where  the  blood  abounds  in  Bacillus  anfhracis,  shown  in 
Fia  68. 


Fig.  68. — Bacillus  aDthriicis.  (After  Koch.)  A,  Bacilli  mingled  with 
■blood  corp\iscles  from  the  blood  of  a  guinea-pig,  some  of  the  bacilli 
dividing.  B,  the  roiilets  after  three  hours'  culture  in  a  drop  of  aqueous 
humour.  They  grow  out  into  long  leptotlmx-li^e  filaments,  which  be- 
come septate  later,  and  spores  are  developed  in  the  segments,     (x  650.) 

Much  discussion  has  taken  place  as  to  whether  the  i^resence  of  such 
an  organism  is  a  casual,  or  even  a  concomitant  phenomenon,  or  whether 
it  is  the  real  cause  of  the  disease.  It  is  beyond  the  province  of  this 
work  to  discuss  a  question  that  is  chiefly  pathological  in  its  natui^e,  and 
it  is  sufficient  here  to  say  that,  from  the  purely  physiological  stand- 
point, the  presence  of  such  an  organism  in  vast  numbers  cannot  fail  in 
being  inimical  to  the  well-being  of  its  host.  Even  considering  the 
affinity  such  organisms  have  for  oxygen,  it  is  clear  that  a  struggle  will 
ensue  between  them  and  the  living  tissues  for  this  gas ;  and,  if  the  organisms 
secure  the  predominance,  the  living  tissues  must  suffer.  In  addition, 
it  is  not  improbable  (rather  highly  probable)  that  the  organisms  may 
secrete  alkaloidal  substances  of  a  poisonous  nature  which,  in  their  turn, 
may  exert  powerful  physiological  effects  on  the  tissues  and  organs. 

The  growth  and  development  of  schizomycetes  are  influenced  by 
various  physical  and  chemical  agents. 

(1)  Temperature. — A  temperature  of  about  35°  C.  is  the  most  favour- 
able for  the  development  of  the  majority  of  these  organisms.  Cohn  ^ 
states  that  he  has  subjected  bacteria  to  low  temperatures  without 
destroying  their  activity.  He  gives  the  temperatures  as  follows  — 
1  Cohn,  Beitrclge  zur  Biologic  der  Pflanzen,  1870  ;   Zweites  Heft,  s.  221. 


192  THE  CHEMISTRY  OF  THE  BODY. 

Exposure  for  12  hours  30  minutes  to  a  temi)craturc  of  0°  C.  ;  for  1  h. 
30  m.,  to  -  16°  C. ;  for  1  h.  45  m.,  to  -  17°  C. ;  for  3  h.  30  m.,  to  -  18°  C. ; 
for  4  h.  30  m.,  to  - 18°  C. ;  for  5  h.,  to  -  17°-5  C. ;  for  G  h.,  to  -  14°  C. ; 
and  for  7  h.  30  m.,  to  -  9°  C.  He  produced  the  cold  by  freezing  mix- 
tures, and  the  lowest  temperature  he  obtained  was  - 18°  C.  =  0°  F. 
In  1870-71,  Melsens^  exposed  yeast  and  vaccine  lymph  to  very  low 
temperatiu-es  ( -  78°  C.)  obtained  by  means  of  solid  carbonic  acid, 
without  destroying  the  power  of  fermentation  or  of  inociilation. 
Klein ^  states  that  "freezing  destroys  likewise  most  bacteria,  excei)t 
the  spores  of  bacilli,  which  siu-vive  exposure  to  as  low  a  temperature 
as  -  15°  C,  even  when  exposed  for  an  hour  or  more."  Again,  in 
another  place,  he  says  :  "Exposing  the  spores  of  anthrax  bacillus  to  a 
temperatm-e  of  0"  to  -  15°  C.  for  one  hour  did  not  kill  them." 

In  1884,  a  r-emarkable  series  of  experiments  was  described  to  the 
French  Academy  by  MM.  R.  Pictet  and  E.  Yung.-'  These  observers 
sealed  up  in  small  glass  tubes  fluids  containing  various  kinds  of  micro- 
phytes, and  placed  them  in  a  wooden  box.  The  box  was  in  the  first 
place  submitted  for  20  hours  to  a  cold  of  —  70°  C,  produced  by  the 
evaporation  of  liquid  sulphurous  acid  in  vacuo.  The  box  was  then  sur- 
rounded by  solid  carbonic  acid  for  89  hours,  and  a  cold  of  from  -  70°  to 

-  76°  C  Avas  thus  obtained.  Finally  the  box  Avas  subjected  for  a  third 
period  of  20  hours  to  a  cold  produced  by  the  evaporation  of  solid 
carbonic  acid  in  vacuo — the  temperature  being  estimated  at  from  —76° 
to  -  130°  C,  that  is,  a  minimum  temperature  of  202°  below  zero  F. 
They  sum  up  by  stating  that  the  organisms  were  acted  on  by  a  cold  of 

-  70°  C.  for  109  hours,  followed  by  a  temperature  of  -  130°  C.  for  20 
hours.  The  organisms  tested  were  Bacillus  anthrads.  Bacillus  subtilis, 
Bacillus  ulna,  Micrococcus  luteus,  and  a  micrococcus  not  determined. 
Bacillus  aiithracis  retained  its  virulence  when  injected  into  a  living- 
animal.  The  vitality  of  the  others  was  not  affected.  Experiment 
showed  that  whilst  cold  seemed  to  kill  some  of  the  micrococci,  a  great 
number  resisted  it.  Yeast  showed  no  alteration  under  the  microscope, 
but  it  had  lost  its  powers  of  fermentation.  Vaccine  lymph  exj^osed  to 
the  low  temperatures  did  not  produce  a  pustule  on  the  left  arm  of  an 
infant,  whilst  another  sample  of  the  same  lymph  introduced  into  the 
right  arm  of  the  same  child  produced  a  pustule.  Pictet  and  Yung  con- 
clude from  their  experiments  that,  in  the  conditions  of  cold  indicated, 
many  of  the  lower  organisms  were  not  destroyed. 

^  Melsens,    Compte>i   Rendu^,   tome   Ixx.    1870,   p.   G29  ;    also   Comptes  Rendus, 
tome  xxi.  p.  3"2o. 
-  Klein,  Micro-organisms,  p.  35. 
"  Pictet  and  Yung,  Comptvs  Rendits,  tome  xcviii.  No.  12,  p.  747. 


FERMENTATION.  I93 

In  1885,  J.  J.  Coleman  and  the  author'  made  numerous  experiments 
in  which  very  low  temperatures  were  reached  and  maintained  for  many 
hours  by  the  use  of  a  special  modification  of  the  cold-air  engines  invented 
by  Mr.  Coleman,  now  largely  used  in  the  industry  of  importing  meat 
into  Great  Britain.  Although  putrescible  infusions  and  fresh  meat  con- 
tained in  hermetically  sealed  bottles  were  exposed  to  a  temperature 
of  —83°  C.  for  100  consecutive  hours,  putrefaction  soon  began  when  the 
bottles  were  removed  to  a  warm  room.  It  was  found  impossible  to  pro- 
duce sterilization,  that  is,  to  kill  the  schizomycetes  or  their  spores,  by  cold. 

On  the  other  hand,  high  temperatures  are  more  fatal.  The  spores  of 
bacilli,  hoAvever,  may  germinate  after  the  fluid  has  been  boiled  (100°  C.) 
for  an  hour,  and  it  is  said  that  they  have  mthstood  a  temperature  of 
even  110°  C.  Dry  spores  resist  a  higher  temperature  than  sj)ores  in  a 
moist  state,  and  it  would  appear  that  ripe  spores  are  more  resistant 
than  spores  in  the  germinating  state.  Spores  are  killed  also  at  a  lower 
temperature  in  acid  media  than  in  alkaline  media.  Probably  prolonged 
boiling  Avould  ultimately  kill  all  spores.  Tyndall^  ascertained  that 
discontinuous  heating,  that  is  rej^eatedly  boiling  the  solutions  contain- 
ing spores  for  half  an  hour  daily,  sterilized  the  fluid  in  two  or  three  days, 
although  boiling  the  same  kind  of  fluid  (100°  C.)  for  half  an  hour  once 
did  not  produce  this  eff'ect.  The  explanation  offered  is  that  spores  not 
killed  by  the  first  boiling  may  germinate  before  the  second  boiling,  and 
if  caught  in  the  germinating  state  they  are  killed,  whilst  some  not 
germinating  may  again  escape. 

(2)  TFater. — Schizomycetes  germinate  only  in  a  fluid,  but  spores  may 
remain  alive  in  a  dormant  dry  state  for  months  or  years.  Thus  Bacillus 
suhtilis  has  been  kept  alive  in  a  dry  state  for  years.  More  extended 
observations  are  required  on  this  point  with  regard  to  many  species, 
but  it  is  obvious  that  they  may  live  in  the  dry  state  and  be  wafted 
about  by  air  currents. 

(3)  Light. — Brilliant  sunshine  appears  to  be  inimical  to  the  spores 
of  certain  species,  and  flasks  may  be  partially,  if  not  wholly,  steril- 
ized by  being  exposed  to  sunlight.  On  the  other  hand,  it  is  not 
unlikely  that  light  may  encourage  the  development  of  other  species, 
more  especially  in  fluids  and  in  the.  vicinity  of  chlorophyll-bearing- 
organisms,  as  shown  by  Engelmann's  experiment  described  at  p.  24. 
Aerobiotic  forms  collect  where  the  oxygen  is  being  evolved  from  chloro- 
phyll, in  the  yellow-red  part  of  the  spectrum. 

^  Coleman  and  M'Kendrick,  Proceedings  of  Royal  Institution  of  Great  Britain, 
Lecture  on  "The  Mechanical  Production  of  Cold  and  Effects  of  Cold  on  Micro- 
phytes," 29th  May,  1885. 
2  Tyndall,  Floating  Matter  in  the  Air,  1881. 
I.  N 


194  THE  CHEMISTRY  OF  THE  BODY. 

(4)  Ozone. — The  author  has  attempted  to  sterilize  organic  fluids  and 
solids  by  means  of  ozone,  but  without  success,  although  it  was  evident 
that  ozonization  of  the  air  or  of  an  atmosphere  of  oxygen  delayed  con- 
siderably the  advent  of  putrefaction. 

(5)  Pressure. — Paul  Bert  ascertained  that  putrefaction  was  prevented 
in  flesh,  moist  bread,  fruits,  etc.,  by  pure  oxygen  under  a  pressure  of 
from  10  to  27  atmospheres,  but  that  air  under  the  same  pressure  had  no 
effect  in  delaying  putrefaction. 

(6)  Chemical  substances. — Schizomycetes  resist  the  action  of  certain 
substances  that  might  be  supposed  capable  of  destroying  them.  Thus 
Bacillus  anthracis  survived  several  weeks'  immersion  in  absolute  alcohol. 
On  the  other  hand,  they  are  killed  by  carbolic  acid,  salicylic  acid, 
quinine,  hydroxylamine,  sulphurous  acid,  corrosive  sublimate,  chlorine, 
and  the  mineral  acids. 

(5)  Modes 'of  Cultivating  Schizomtcetes. 

Bacteriology,  or  the  department  of  biology  relating  to  the  growth  and 
development  of  the  schizomycetes,  has,  during  the  past  four  or  five  years, 
become  so  important  in  connection  with  the  germ  theory  of  disease,  as 
to  have  led  to  a  remarkable  develojDment  of  experimental  methods  by 
which  these  organisms  may  be  studied  under  scientific  conditions.  To 
describe  these  methods  in  detail  is  beyond  the  scope  of  this  work,  and 
all  that  is  attempted  is  to  give  the  student  a  short  sketch  of  the  general 
princii^les  on  which  bacteriologists  proceed. 

Bacteria  may  be  artificially  cultivated  in  or  upon  media  so  prepared 
as  to  meet  the  requirements  of  microscopical  investigation.  As  a  rule, 
they  grow  well  upon  any  organic  substance  containing  nitrogen  and 
carbon,  of  a  slightly  alkaline  reaction,  and  at  a  suitable  temperature. 
This  substance  may  be  either  liquid  or  solid.  Pasteur's  fluid,  e.g.  con- 
sists of  a  solution  of  1  part  of  tartrate  of  ammonia,  10  parts  of  candy 
sugar,  and  the  ash  of  1  part  of  yeast  in  100  parts  of  water.  Cohn's  liquid 
consists  of  "5  grm.  phosphate  of  potash,  -5  grm.  sulphate  of  magnesia, 
•05  grm.  tribasic  phosphate  of  lime,  and  1  grm.  tartrate  of  ammonia,  in 
100  grms.  of  water.  Infusions  or  decoctions  of  fruit,  vegetables,  or  flesh 
are  also  employed.  A  very  serviceable  bouillon  (or  beef-tea)  may  be 
made  by  boiling  500  grms.  of  finely  minced  beef  in  a  litre  of  water  for 
three  quarters  of  an  hour.  It  is  rendered  alkaline  by  adding  a  few  drops 
of  a  saturated  solution  of  carbonate  of  soda,  and  filtered  to  obtain  a  per- 
fectly clear  fluid.  This  is  placed  in  glasses  with  stoppers  of  cotton-wool 
and  sterilized  by  exjjosure  to  the  temperature  of  boiling  water  for  about 
three  quarters  of  an  hour  on  three  successive  days — "discontinuous 
sterilization." 


FERMENT  A  TION.  195 

A  great  objection  to  the  cultivation  of  bacteria  in  liquids  is  that  it  is 
-exceedingly  difl&cult  to  get  a  "pure  cultivation"  that  is  to  say,  a  special 
variety  of  micro-organism  growing  without  admixture  of  other  kinds. 
Accordingly  various  solid  or  semi-solid  substances  are  used,  upon  whose 
surface  a  single  variety  may  be  isolated  and  examined.  Thus,  the  cut 
surface  of  a  boiled  potato  affords  a  very  suitable  nidus  for  many  varieties 
of  bacteria.  The  potato  is  sterilized  by  being  washed  with  a  1  to  1000 
solution  of  corrosive  sublimate.  It  is  then  boiled  for  about  three 
quarters  of  an  hour,  cut  into  two  |)ieces  by  a  knife  which  has  been 
:sterilized  by  being  heated  in  a  flame,  and  placed  under  a  glass  cover  for 
protection.  Bread  rubbed  to  a  fine  powder,  moistened  with  distilled 
water,  and  sterilized  by  discontinuous  heating  is  frequently  employed 
for  the  study  of  moulds  and  fungi.  An  exceedingly  useful,  firm,  clear, 
transparent  jelly  is  made  in  the  foUo'v^ang  way :  500  grms.  of  finely 
minced  lean  beef  are  soaked  for  24  hours  in  a  litre  of  water  and  strained 
through  a  muslin  cloth  so  as  to  give  a  litre  of  meat-juice.  To  this  are 
added  10  grms.  of  peptone  powder,  5  grms.  of  common  salt,  and  100 
^rms.  of  the  best  (French)  gelatin.  The  mixture  is  well  shaken  and 
heated  till  the  gelatin  is  completely  liquefied.  It  is  then  made  slightly 
alkaline  with  a  saturated  solution  of  carbonate  of  soda,  filtered  while 
warm  into  glass  vessels  or  test  tubes,  and  sterilized  by  discontinuous 
heating.  Sometimes  1  or  2  per  cent,  of  grape  sugar  is  added  to  the 
.above  preparation. 

As  this  jelly  melts  at  a  temperature  of  25°  C,  it  is  unsuitable 
for  the  cultivation  of  such  organisms  as  grow  only  at  temperatures 
more  nearly  approaching  that  of  the  human  body  (37°-38°  C).  To  meet 
this  objection,  from  10  to  20  grms.  of  Agar-agar,  a  gelatinous  substance 
•obtained  from  various  kinds  of  seaweed,  may  be  substituted  for  the 
gelatin,  the  other  constituents  remaining  as  above.  The  jelly  so 
•obtained  is  not  quite  so  clear  as  when  gelatin  is  employed,  and  the 
process  of  filtration  is  rendered  very  slow  by  the  tendency  of  the  agar- 
agar  to  gelatinize  when  the  temperature  falls  below  the  boiling  point. 
For  the  growth  of  certain  micro-organisms,  such  as  the  bacillus  of  tuber- 
culosis, blood-serum  is  employed,  made  firm  by  heating  to  68°  C  for 
.about  an  hour.  If  heated  to  a  higher  temperature,  it  becomes  grey, 
opaque,  and  unsuitable  for  microscopical  research.  It  is  sterilized  by 
being  heated  to  a  temperature  of  from  56°  C  to  58°  C,  tAvo  hours  daily 
for  about  eight  days,  or  if  the  blood  of  a  healthy  animal  is  carefully 
drawn  off  into  cold  sterilized  vessels,  the  serum  may  be  obtained  at 
once  free  from  micro-organisms  and  requires  no  further  sterilization. 

Before  any  of  the  above-mentioned  substances  can  be  used  for  the  cidti- 
vation  of  bacteria,  all  instruments  and  utensils  that  may  come  in  contact 


196  THE  C HEM  IS  TR  Y  OF  THE  BOD  T. 

with  them  must  be  completel}-  sterilized.  All  metallic  instruments  re- 
quired, such  as  knives,  scissors,  forceps,  needles,  and  wires  may  be  sterilized 
by  being  heated  in  the  flame  of  a  Bunsen  burner  for  about  half  a  minute. 
Glass  utensils,  such  as  covers,  slides,  and  test-tubes  are  placed  in  an 
oven  at  a  temperature  of  160°  C,  and  after  the  lapse  of  about  half  an 
hoiu"  are  found  to  be  sterilized.  For  the  sterilization  of  nutrient  media, 
a  long  cylindrical  vessel  "vnth  a  jacket  of  felt  and  a  perforated  cover  is- 
used  in  which  water  is  kept  boiling  and  the  substances  to  be  sterilized 
are  suspended  in  the  rising  steam  for  about  three  cpiarters  of  an  hour 
for  three  successive  days.  But,  if  the  substance  contains  much  albumin, 
as,  e.g.  blood-serum,  it  is  then  warmed  for  about  three  or  four  hours- 
daily  to  a  temperature  of  from  56°-58°  C.  for  a  week,  during  which  time 
all  germs  which  have  been  present  at  the  beginning  of  the  process  have 
developed  into  mature  forms  and,  as  such,  been  destroyed. 

Suppose,  now,  we  wish  to  make  a  pure  cvdtivation  of  a  special  micro- 
organism, we  may  proceed  by  various  methods.  If  the  potato  is  to  be 
used,  a  small  ci[uantity  of  the  material  supposed  to  contain  the  desired 
variety  is  taken  upon  the  point  of  a  sterilized  knife  and  rubbed  evenly 
over  the  cut  surface  of  the  potato,  care  being  taken  not  to  touch  its- 
circumference  at  any  part.  From  the  centre  of  this  surface,  a  minute 
portion  is  now  taken  and  rubbed  over  the  surface  of  a  second  half;  a 
little  of  the  second  is  conveyed  to  a  third,  and  so  on,  until  six  or  seven 
halves  have  been  successively  inoculated  one  from  the  other.  It  will- 
be  readily  understood  that  only  an  exceedinglj-  minute  portion  of  the 
original  material  can  be  present  ujDon  the  surface  of  the  sixth  or  seventh 
potato.  All  the  pieces  are  placed  under  a  glass  cover,  and  they  are 
kept  from  drj'ing  by  placing  moist  blotting  paper  beside  them.  In  the 
course  of  a  few  days,  a  vari-coloiu-ed  film  will  probably  be  seen  covering 
the  surface  of  the  potato  first  inoculated,  composed  of  colonies  of 
various  species  of  micro-organisms.  On  the  second  potato,  this  layer 
■vsoll  be  slightly  broken  up  as  the  germs  which  have  given  rise  to  the 
3'oung  colonies  have  been  more  separated  from  one  another  than  in  the 
first  case.  On  the  sixth  or  seventh  there  Avill  probably  be  only  one  or 
two  small  colonies  which  have  sprung  from  single  germs,  and  in  these 
we  have  a  pure  cultivation  of  a  special  variety  ready  for  examination 
or  further  separate  cultivation. 

If  the  gelatin  or  agar-agar  preparations  are  to  be  used,  three 
test-tubes  about  half  full  of  the  jelly  are  placed  in  a  water  bath 
at  a  temperature  high  enough  to  liquefy  the  jelly.  A  small  quan- 
tity of  the  material  to  be  investigated  is  introduced  into  one  of 
the  test-tubes  and  stirred  about  in  it  by  means  of  a  sterilized 
platinum  wire,  the  end  of  which  has  been  bent  round  so  as  to  form  a. 


FERMEXTATIOX.  197 

small  loop.  The  "wire  is  no'w  sterilized  in  the  Bimsen  flame,  cooled, 
and  by  its  means  a  small  drop  of  the  liquid  in  the  first  tube  is  trans- 
ferred to  that  of  the  second,  and  intimately  mixed  with  it.  Similarly, 
from  the  second  a  small  drop  is  transferred  to  the  third.  As  "with  the 
cultivation  on  the  potato,  so  here  there  can  be  very  little  of  the  original 
material  in  the  third  test-tube.  In  order,  no"w,  to  obtain  a  some"what 
large  surface  upon  "which  the  micro-organisms  may  gro"w  separate  from 
one  another,  the  mouths  of  the  test-tubes  are  sterilized  by  gentle  heating 
in  the  flame,  and  the  licjuid  gelatin  or  agar-agar  is  poured  on  to 
cold  sterilized  glass  plates,  "where  it  quickly  forms  a  thin  layer  of  firm 
jellv.  The  plates  are  covered  "with  a  glass  shade,  the  air  being  kept 
moist  as  described  above,  and  the  gro"wth  of  the  cultivation  observed. 
The  special  variety  of  micro-organism,  if  present,  may  be  recognized 
either  by  the  naked  eye  appearance  of  the  colony,  or  by  microscopical 
examination  of  a  small  portion  of  it,  stained  or  unstained  as  may  be 
desired.  Let  us  suppose  that  the  variety  "we  "wish  to  examine  has  been 
isolated  and  recognized,  "we  may  -wish  to  cultivate  it  further  by  itself. 
In  this  case  a  minute  portion  of  a  colony  is  Lifted  on  the  point  of  a 
sterilized  platinum  "wire,  the  cotton-"wool  stopper  of  a  gelatin  or  agar- 
agar  tube  is  removed,  and  the  "wire  is  thrust  do"wn  through  the  jelly 
and  cj[uickly  "withdra^m,  lea"\"ing,  as  it  passes  out,  the  micro-organisms 
adherent  to  the  jelly,  or,  if  the  jeUy  has  become  firm  in  an  inclined  tube, 
so  that  it  has  a  long  sloping  surface,  a  line  may  be  dra"wn  upon  this 
surface  "with  the  end  of  the  platinum  "wire,  lea^ang  the  micro-organisms 
exposed  to  the  air  in  the  tube.  Here  the  micro-organisms  gro"w,  and 
their  appearance  may  be  noted  from  time  to  time.  Gro"wth  may  go  on  at 
the  ordinary  atmospheric  temperature,  or  it  may  require  the  tempera- 
ture of  the  human  body  (ST'-SS"  C).  In  this  case,  tubes  containing 
agar-agar  or  blood-serum  are  used,  and  are  placed  in  an  incubator,  one 
form  of  "which  is  represented  in  Fig.  69.  In  this  the  temperature  is 
maintained  constantly  at  the  required  height,  any  changes  being  pre- 
vented by  the  use  of  a  thermo-regulator,  one  form  of  "which  is  sho"wn  in 
Fig.  70.  It  consists  of  a  three-"way  tube  (/),  the  lo"wer  end  of  "which 
passes  down  through  a  caoutchouc  stopper  to  near  the  bottom  of  a  test 
tube  {u)  containing  mercury.  In  very  sensitive  instnunents,  a  diaphragm 
through  "which  the  tube  passes  is  placed  at  the  centre  of  the  test-tube, 
and  immediately  belo"w  this  diaphragm  is  a  small  quantity  of  a  mixture 
of  alcohol  and  ether,  "which,  "when  heated,  expands  much  more  rapidly 
than  mercury.  To  the  upper  end  of  the  tube  {t)  is  fixed  an  india-rubber 
tube  bringing  gas.  In  this  end  of  the  tube,  ho"wever,  there  is  a 
caoutchouc  stopper  (not  seen  in  the  diagram),  through  -which  passes  a 
smaller  tube  (/),  the  lo"wer  end  of  "which  is  cut  in  a  slanting  direction 


198 


thl:  chemistry  of  the  body 


towards  the  mcrcur3\      Gas  can  only  pass  into  the  three-way  tube 
through  the  smaller  tube  (t),  and  thence  it  is  led  by  the  horizontal  arm 


Fig.  to. — Thermo-regulator.  u^ 
test-tube  with  mercury  ;  I,  three- 
way  tube  ;  2,  smaller  tube  through 
which  gas  passes  into  I  ;  a,  small 
aperture  in  i ;  c,  tube  to  burner. 


Fig.  69. — Inoubator. 


(c)  and  an  india-rubber  tube  to  a  burner  placed  below  the  incu.- 
bator.  There  is  a  minute  opening  in  the  tube  (^)  at  («),  the  object  of 
which  will  soon  become  evident.  When  the  instrument  is  to  be  used, 
the  test-tube  is  passed  into  the  incubator  through  an  aperture  in  its 
cover,  and  the  gas  is  lit.  As  the  temperature  inside  the  incubator  rises, 
the  mercury  expands,  and  is  forced  up  into  the  tube  (/)  until  it  reaches 
the  tube  (i).  Continuing  to  rise,  it  gradually  shuts  off  the  gas,  and  the 
flame  becomes  smaller ;  but  if  the  mercruy  still  rose,  the  stream  of  gas 
would  be  cut  ofi"  altogether,  and,  the  flame  being  extinguished,  the  mer- 
cury would  fall  and  the  gas  escape  were  it  not  for  the  minute  aperture 
(a),  which  always  permits  a  very  small  cpantity  of  gas  to  find  its  way 
to  the  burner,  and  prevents  the  extinguishing  of  the  flame.  But  the 
flame  is  now  so  small  that  the  temperature  of  the  incubator  falls,  the 
column  of  mercury  descends,  the  tube  (i)  is  opened,  the  gas  streams. 


FERMENT  A  TION.  199 

into  (/),  and  the  flame  enlarges.  The  lower  end  of  the  tube  (i)  is  placed 
at  such  a  height  above  the  surface  of  the  mercury  that  the  flame  will 
be  lowered  when  the  temperature  reaches  any  desired  point.  The 
flame  is  guarded  by  a  screen,  and  when  once  heated,  the  incubator 
remains  at  the  same  temperature  for  any  length  of  time. 

By  means  of  the  incubator  we  can  study  the  life  history  of  many 
varieties  of  micro-organisms  which  would  either  perish  or  whose  growth 
would  be  much  retarded  by  exposure  to  lower  temperatures.  This  is 
the  more  important  because  many  such  micro-organisms  can,  when 
introduced  into  the  tissues  of  living  animals,  occasion  serious  disturb- 
ances in  the  vital  processes  of  the  part  inoculated  or  even  of  the  whole 
organism,  and  consequently  the  study  of  such  forms  is  of  the  profoundest 
interest  and  importance  alike  to  the  physiologist  and  the  physician. 
Much  as  has  been  done  in  this  field  of  research,  very  much  more  still 
remains  to  be  done.  Much  has  still  to  be  discovered  about  those  varieties 
which  have  been  isolated  and  cultivated  artificially,  and  we  know  that 
there  are  still  many  forms  which  cannot  be  so  cultivated  partly  because 
the  different  nutritive  media  in  use  are  not  suited  to  their  requirements, 
and  partly  because  we  cannot  supply  the  proper  environment  without 
which  they  must  perish.  Certain  varieties  can  only,  so  far  as  we  know, 
develop  and  be  propagated  in  the  bodies  of  living  animals,  some,  indeed, 
seem  to  be  limited  to  a  single  species  of  animal.  Having  once  found  a 
lodgment,  however,  they  give  rise  to  a  series  of  symptoms,  so  definite  in 
their  order,  so  characteristic  in  their  appearance,  and  so  grave  in  their 
result,  that  we  are  frequently  warranted  in  inferring  their  presence  from 
the  manifestation  of  the  symptoms.  We  must  not,  however,  regard  any 
micro-organism  as  the  specific  cause  of  a  definite  disease  unless  it  satisfies 
the  following  conditions-^ 

Firstly,  it  must  be  present  in  the  tissues  of  every  animal  suffering 
from  the  disease,  and  not  in  others. 

Secondly,  we  must  be  able  to  isolate  and  cultivate  it  outside  of  the 
organism  of  the  diseased  animal,  so  that  it  is  entirely  free  from  contact 
with  diseased  tissue  of  any  kind. 

Thirdly,  after  inoculation  with  the  pure  cultivation,  of  the  tissues  of 
healthy  animals,  it  must  produce  in  them  the  same  disease. 

Consult  on  matters  relating  to  physiological  chemistry,  in  addition  to  the 
works  referred  to  in  the  text,  Hoppe-Seyler — Physiologische  Chemie,  1877- 
1881;  Arthce,  Gamgee — Physiological  Chemistry  of  the  Animal  Body; 
Beaunis  —  Physiologic  Humaine,  vol.  I.;  the  articles  on  the  subject  in 
Hermann's  Handbvich  der  Physiologic  ;  Witthaus — Medical  Student's  Manual 
.  of  Chemistry,   1884.      See  also  Prof.  P.  W,  Latham's  Croonian  Lecture,  1886. 


200  THE  CHEMISTRY  OF  THE  BODY. 

In  discussing  the  pathology  of  Gout  and  Diabetes,  he  has  advanced  a  theory 
regarding  the  formation  of  uric  acid,  which  may  be  briefly  stated  as  follows — 
"  The  glycocin,  instead  of  undergoing  in  the  human  subject  the  normal  change 
into  urea,  combines  in  the  liver  with  two  molecules  of  urea,  derived  from  the 
other  amido-acids,  leucin,  etc.,  and  forms  the  compound 

CO  ■{  NH— CHo— COOH  ; 

that  is  a  compound  containing  one  more  molecule  of  CONH  than  hydantoic  acid, 
and  allied  to  biuret  and  alloplianic  ether.     This  substance  dehydrated  forms 

p^iNH— CO 

CO\NH— CHa, 
which,  like  hydantoin,  is  soluble  in  the  blood,  passes  on  to  the  kidneys,  and  is 
there  conjugated  with  another  molecule  of  urea,  and  forms  ammonium  urate — 

COJNH       I  +     CO-  JJil^      =     H,0  +  CgHaNA-NH^, 

COINH— CH.  '^'■^^2 

Urea.  Ammonium  urate. 

which  is  excreted ;  but,  a  portion  overflowing  from  the  kidney  into  the  general 
circulation  and  meeting  with  soda  in  the  blood,  is  converted  into  sodium  urate." 
^See  Lancet,  1884,  vol.  L,  p.  485;  and  Lancet,  1885,  vol.  I.,  p.  1120.) 


201 


SECTION  III. 

THE  PHYSIOLOGY  OF  THE  TISSUES. 

Chap.  I.— HISTORICAL  INTRODUCTION. 

The  morphology  and  physiology  of  the  tissues  are  included  under  the 
common  term  Histology.  Before  entering  on  the  consideration  of  the 
individual  tissues  we  shall  take  a  historical  survey  of  the  steps  by  which 
our  present  knowledge  has  been  attained.  This  survey  will  give  an  in- 
telligent comprehension  of  the  more  modern  views  held  regarding  the 
structure  of  living  matter  and  the  origin  of  the  various  tissues. 

It  is  evident  that  knowledge  of  the  structure  of  the  tissues  must  depend 
chiefly  on  the  degree  of  excellence  of  the  microscope,  and  on  the  skilful 
adaptation  of  methods  of  preparing  these  for  examination  by  that  instru- 
ment. ]S[o  doubt  simple  lenses  enabled  Eobert  Hooke,  Malpighi,  Grew, 
and  Leeuwenhoek,  in  the  17th  century,  to  discover  some  of  the  cellular 
elements,  and  by  such  simple  instruments  Fontana,  in  1780,  saw  and 
described  the  nucleus  of  the  cell,  adipose  tissue,  striated  muscular  fibres, 
and  the  elements  of  nervous  tissue.  Little  progress,  however,  was  made 
until  early  in  the  present  century,  when,  by  the  application  of  the  prin- 
ciple of  achromatism  by  Fraunhofer,  and  by  its  practical  development 
more  recently  by  Lister  and  others,  the  compound  microscope  became  a 
trustworthy  instrument.  Since  then  each  improvement  in  the  micro- 
scope, as  to  quality  of  lenses,  modes  of  illumination,  and  mechanical 
adjustments,  has  been  accompanied  by  a  contemporaneous  advance  in 
histology.  The  application  of  the  instrument  has  also  been  facilitated 
by  the  gradual  development  of  methods  of  prejmring  the  tissues  for 
examination.  Fontana,  so  long  ago  as  before  1781,  appears  to  have  been 
the  first  to  apply  reagents  to  substances  under  the  microscope,  and  he 
used  alkalies  and  acids  and  even  syrup  of  violets  as  a  coloiu-ing  matter.  ^ 
Little,  however,  was  done  in  this  way  until  about  the  middle  of  the 
present  century.  Since  then  scarcely  a  year  has  elapsed  without  the 
invention  of  an  improved  method. 

^  Camoy,  La  Biologic  Gellulaire. 


202  THE  PHYSIOLOGY  OF  THE  TISSUES. 

Thus  Purkinje  and  Bauschel  and  Burdach  used  acetic  acid  as  a  reagent  to  clear 
up  the  tissues ;  Gerlach  showed  how  to  fill  the  minute  blood-vessels  with  trans- 
pai'eut  injection  ;  H.  Midler  devised  the  method  of  hardening  tissues  by  steeping 
them  for  long  periods  in  solutions  of  chromic  acid  or  of  its  salts  ;  the  plan  of  stain- 
ing certain  elements  was  followed  by  Lord  Sydney  Godolphin  Osborne,  Gerlach, 
and  Lionel  Beale,  with  carmine,  and  by  Waldeyer,  with  logwood  or  hematoxylin ; 
Rainey  showed  how  to  render  tissues  transparent  by  glycerine;  Loukhart  Clarke 
made  it  possible  to  render  nervous  tissues  transparent  liy  passing  them  through 
alcohol,  oil  of  turpentine,  oil  of  cloves,  and  finally  mounting  them  in  Canada 
balsam  ;  Rollet  and  Schwartz  invented  the  method  of  double  staining,  so  that  one 
element  of  tissue  might  be  tinted  red  by  carmine,  whilst  other  elements  were  tinted 
yellow  by  picric  acid  ;  Eanvier,  Jtirgens,  Di-eschfield,  and  others  called  to  our  aid 
the  coal  tar  colours ;  and  Krause,  His,  and  Von  Recklinghausen  introduced  the 
use  of  salts  of  silver.  Max  Schultze,  the  use  of  osmic  acid,  Cohnheim,  the  use  of 
chloride  of  gold,  and  F.  E.  Schulze,  the  use  cf  the  salts  of  palladium- -these 
observers  ha^■ing  ascertained  that  certain  elements  of  tissue  reduce  these  salts, 
precipitating  the  metal  in  such  a  condition  that  by  lines  or  marks  the  eye  can 
follow  details  in  structures  that  otherw  ise  would  show  no  optical  indication  of 
their  presence. 

By  such  operations  of  micro-chemistry,  aided  hy  improved  methods  of 
cutting  thin  sections,  and  by  the  use  of  microscopes  that,  considered 
merely  as  optical  instruments,  are  probably  very  near  the  state  of  per- 
fection, much  progress  has  recentlj^  been  made,  more  especially  in  the 
obscure  department  of  histology  dealing  with  the  nature  of  proto- 
plasm, the  structure  of  cells,  and  the  phenomena  of  fecundation. 

As  already  stated,  the  earliest  observers  with  the  simple  microscope 
undoubtedly  saw  some  of  the  cellular  elements  of  the  tissues  both  of 
plants  and  of  animals,  but  the  first  important  step  taken  was  by  the 
botanist,  Robert  Brown,  who,  in  1831,  made  great  j)rogress  in  the 
knowledge  of  vegetable  cells.  In  particular,  he  directed  special  attention 
to  the  nucleus,  previously  observed  by  Fontana,  and  established  the  fact 
that  it  was  a  normal  element  in  the  cell.  In  1836,  Valentin  discovered 
the  nucleolus,  and  he  described  it  as  a  little  round  body,  a  kind  of 
second  nucleus,  in  the  interior  of  the  first.  As  to  the  physiological 
significance  of  cells,  Turpin,  so  early  as  1826,  was  the  first  to  attribute 
to  them  distinct  individualities,  and  to  make  the  generalization  that 
plants  were  formed  by  an  agglomeration  of  cells.  Then  came  the 
announcement  of  the  cell  theory  in  1839,  first  applied  to  plants  by 
Schleiden,  and  then  to  animals  by  Schwann.  A  careful  study  of  the 
history  of  this  subject  has  convinced  me  that  even  before  1830,  the  cell 
theory  was  held  generally  by  botanists,  and  was  discussed  more 
especially  in  the  writings  of  Dutrochet,  Mayen,  Schleiden,  and  Yon 
Mohl ;  but  it  was  not  put  on  a  sure  liasis  until  it  was  applied  to  animal 
tissues  by  Schwann.    At  this  period  then,  1839,  the  conception  of  a  cell 


HISTORICAL  INTRODUCTION.  203 

was  as  follows — "  A  vesicle  dosed  hy  a  solid  memhxme,  containing  a  liquid 
in  which  floats  a  nucleus  containing  a  nucleohis,  and  in  tchich  also  one  may 
find  smcdl  granular  bodies."  Further,  it  was  held  by  the  founders  of  the 
cell  theory  that  all  cells  might  originate  in  a  structureless  substance  or 
kytoblastema.  The  cell  theory  itself  was  contained  in  the  statements 
that  the  bodies  of  all  plants  and  animals  are  formed  originally  of  cells, 
and  that  it  is  by  the  evolution  of,  and  changes  in,  these  cells  that  all 
the  tissues  are  formed  (Fig.  71). 


Fir,.  71. — (1)  Original  conception  of  a  cell,  a,  cell  wall ;  b,  nucleus  ; 
c,  cell  substance  or  contents  ;  d,  nucleolus.  (-I)  Cell  wall  has  dis- 
appeared, b,  nucleus  ;  a,  nucleolus  ;  c,  cell  substance  or  con- 
tents. (M)  Modern  view.  Cell  now  consists  of  sjranular  matter. 
Even  the  faint  line,  c,  might  be  omitted  ;  no  cell  wall  exists. 

The  cell  theory  rapidly  underwent  modification  under  the  influence 
of  new  facts  and  of  philosophical  speculation.  Thus,  in  1841,  Henle 
showed  that  cells  may  multiply  by  budding,  and  in  the  same  year 
Martin  Barry  observed  that  the  reproduction  of  cells  was  accompanied 
by  division  of  the  nucleus.  In  1845,  Goodsir  first  promulgated  the 
doctrine  that  cells  never  originate  without  pre-existing  cells,  a  doctrine 
subsequently  adopted  by  Remak  and  applied  to  pathological  phenomena 
by  Virchow.  Then,  in  1845,  the  botanist,  Naegeli,  showed  that  certain 
cells  have  no  cell  wall,  and  in  1857,  Leydig  defined  a  cell  as  a  soft  sub- 
stance containing  a  nucleus.  Lastly,  in  1854,  Max  Schultze  described 
a  non-nucleated  amoeboid  organism.  Amoeba  poirecta,  that  is  a  cell  in  the 
physiological  sense,  but  destitute  of  either  cell  wall,  nucleus,  or 
nucleolus,  nothing  in  short,  but  a  little  mass  of  apparently  structureless 
matter.  Thus,  we  come  back  to  a  structureless  substance,  and  in  this 
connection  it  is  interesting  to  read  the  following  quotation  from 
Schwann,  because  it  indicates  the  comprehensive  view  taken  by  him 
of  the  nature  of  living  matter — "  In  the  fundamental  phenomena 
attending  the  exertion  of  productive  power  in  organic  nature, 
a  structureless  substance  is  present  in  the  first  instance,  either 
around,  or  in  the  interior  of  cells  already  existing ;  and  cells 
are  formed  in  it  in  accordance  with  certain  laws,  which  cells 
become  developed  in  various  ways  into  the  elementary  parts  of  an 
organism."^ 

"^  For  an  interesting  accovint  of  the  earlier  views  regarding  cells,  see  Dr.  Drj-s- 
dale's  Protoplasmic  Theory  of  Life,  1874.     Dr.  Drysdale  in  particular  refers  to- 


•204  THE  PHYSIOLOGY  OF  THE  TISSUES. 

Now,  we  must  retrace  our  steps  to  ascertain  what  were  the  earlier 
views  held  by  naturalists  regarding  living  matter.  As  early  as  1839, 
Brisscau-Mirbel  applied  the  term  camUinn  to  the  living  matter  in  })lants, 
and  a  little  later  Schleiden  called  it  mucilage  or  schleim.  In  1835,  the 
French  naturalist  Dujardin,  in  describing  the  Rhizopoda,  first  used  the 
word  sarcode  to  designate  "a  kind  of  mucus  endowed  with  sj^ontaneous 
movement  and  contractility."  Then  a})peared  the  fomous  Avord,  ^^ro^o- 
j)lasm.  According  to  Carnoy,  this  term  Avas  first  used  hy  Purkinje,  and 
he  makes  the  following  quotation  from  Reichcrt,  Avho,  in  describing 
Purkinje's  researches,  Avhich  were  published  in  1839  and  1840,  says — 
"  There  is  only,  according  to  Purkinje,  a  decisive  analogy  between  the 
two  organic  kingdoms  in  that  relating  to  the  elementary  granules  of 
the  vegetable  cambium  and  of  the  protoplasm  of  the  animal  embryo." 
Six  years  later,  in  1846,  Hugo  von  Mohl,  in  describing  the  tissues  of 
plants,  used  the  word  and  defined  the  appearance  of  protoplasm  in  such 
a  manner  as  to  entitle  him  to  the  credit  of  the  first  scientific  use  of  the 
term.  He  A\Tites — "  I  am  authorized  to  give  the  name  of  protoplasm 
to  a  semi-fluid  nitrogenous  substance,  stained  yellow  by  iodine,  which  is 
contained  in  the  cavity  of  the  cell,  and  which  furnishes  the  materials 
for  the  formation  of  the  primordial  utricle,  and  of  the  nucleus."  The 
Avord  protoplasm,  then,  was  first  used  to  designate  the  living  matter  of 
plants,  and  although  Dujardin,  in  1835,  described  the  properties  of  the 
living  matter  of  animals  under  the  name  sarcode,  it  was  a  long  time 
before  naturalists  recognized  the  practical  identity  of  the  two  substances, 
the  matter  called  sarcode  being  supposed  to  be  peculiar  to  the  lower 
orders  of  the  invertebrates.  It  Avas  not  until  1861  that  Max  Schultze 
maintained  the  identity  of  the  sarcode  or  protoplasm  of  the  loAver 
beings  Avith  the  living  matter  in  the  tissues  of  the  higher  beings,  and  it 
is  Avorthy  of  notice  that  this  identity  Avas  grounded  not  on  structural 
but  on  physiological  properties.  Thus  it  Avas  found  that  the  liAdng 
matter  in  vegetable  cells,  as  shoAvn  by  the  Avell-known  phenomenon  of 
the  streaming  of  the  granules,  and  by  the  movements  of  the  sexual 
elements  of  fungi,  had  properties  identical  Avith  those  of  the  sarcode  of 
the  loAver  animals,  and  Avith  those  of  the  living  matter  in  the  higher 

the  early  speculations  of  Dr.  John  Fletcher  in  his  work,  published  in  1835, 
-entitled  Rudiments  of  Pliy.<iohfiy.  The  foUoAving  quotation  from  that  book  shows 
how  adA'anced  Dr.  Fletcher's  speculatiA^e  opinions  were  before  1835  :  "Admitting 
that  irritability  or  A'itality,  general  and  specific,  is  a  property  of  the  organized 
solids  alone,  it  becomes  a  question  of  the  highest  interest  Avhether  it  be  directly 
inherent  in  each  of  the  organized  tissues,  either  of  plants  or  animals,  or  vjhether  it 
merely  apj^ears  to  be  2^ossessed  by  them  all  in  virtue  of  some  one  which  is  universally 
distributed  over  the  organized  being,  and  inextricably  interivoven  ivith  every  other. ^^ 
{\i.  p.  55.) 


HISTORICAL  INTRODUCTION.  205- 

animals.  The  living  stuff,  wlierever  found,  manifested  irritability  and 
contractility,  and  thus  it  was  at  last  held  that  the  living  matter,  or 
protoplasm,  was  the  same  in  kind  in  both  kingdoms  of  organized  beings, 
from  the  lowest  to  the  highest.  Then  it  was  necessary,  about  1865,  ta 
define  protoplasm  as  follows — "A  diaphanous  semi-liquid,  viscous  mass, 
extensible  but  not  elastic,  homogeneous — that  is,  without  structure — without 
visible  organization,  having  in  it  numerous  gramdes,  and  endowed  with 
irritability  and  contractility." 

Protoplasm  having  been  established  as  a  living  stuff,  for  a  time  it  was 
regarded  as  a  structureless  material,  presenting  only  a  feAv  granules, 
and  with  or  without  a  nucleus.  When  a  bit  of  protoplasm  was  verj^ 
small,  even  although  it  had  no  nucleus,  it  was  considered  physiologicallj' 
to  be  a  cell.  But  again  the  restive  onward  movement  began,  which 
led  to  new  conquest.  As  early  as  1844,  Von  Mohl,  in  his  elaborate  in- 
vestigations into  the  structure  of  the  cell,  pointed  out  the  differentiation 
of  the  outermost  layer  of  the  protoplasm  next  the  cell  wall  to  form  the 
primordicd  utricle,  the  vacuolation  of  the  protoplasm,  and  the  nature  of 
the  nucleus,  and  in  1851,  he  limited  his  definition  of  protoplasm  so  as  to 
exclude  the  primordial  utricle  and  the  nucleus,  in  the  following  words — 
"  The  remaining  part  of  the  cell  is  more  or  less  filled  with  an  opaline, 
viscous,  white  fluid,  having  granules  in  it,  and  I  call  this  protoplasm."' 
Thus,  as  remarked  by  Carnoy,  Von  Mohl  limited  the  name  protoplasm 
to  the  hyaline  viscous  portion  of  the  cell  matter.  These  efforts  of  Von 
Mohl  were  the  first  attempts  to  differentiate  the  structure  of  protoplasm  ; 
they  are  the  starting  point  of  a  vast  number  of  researches  in  this  direc- 
tion, in  which  the  investigator  into  vegetable  tissues  goes  hand  in  hand 
with  the  animal  morphologist.  In  1853,  Professor  Huxley  wrote  on 
the  subject,  and  distinguished  between  the  endojjlast,  or  the  matter 
within  the  cell  Avail,  and  the  periplast,  or  surrounding  matter.  He 
attached  special  importance  to  the  endoplast,  homologous  with  the 
primordial  utricle  of  Von  Mohl,  and  held  that  all  differentiations  of 
tissue  were  from  changes  in  the  periplast.  Nor  can  we  forget  the 
impetus  given  to  physiological  speculation  in  this  country  by  his  famous 
lecture  on  protoplasm. 

The  first  step  in  the  direction  of  differentiation  of  the  elements  of  pro- 
toplasm was  made  by  Stilling,  when,  in  1859,  he  discovered  a  fibrillar 
structure  in  the  interior  of  the  ganglionic  nerve  cell.  Five  years  later, 
in  1864,  Leydig  described  a  similar  appearance  in  the  cells  of  the  in- 
testines of  certain  isopod  crustaceans  {Cloporte,  etc.).  Between  the  years 
1865  and  1867,  Frommann  showed  that  a  fibrillar  network  existed  in 
many  cells,  and  in  1873,  Heitzmann  demonstrated  the  sam.e  fact.  The 
two  latter  observers  may  be  regarded  as  the  founders  of  the  modem 


206  THE  PHYSIOLOGY  OF  THE  TISSUES. 

view  that  almost  all  cells,  and  nearly  all  kinds  of  protoplasm,  show  a 
delicate  network  of  fine  fibres,  and  they  established  this  detail  of  stnic- 
ture  as  a  general  property  of  protoplasm.  Thus  protoplasm  is  not 
structureless,  it  is  not  a  homogeneous  mass  having  a  few  granules 
interspersed  in  its  substance,  but  it  has  details  of  structure  so  fine  as  to 
require  the  highest  microscopic  powers,  the  finest  optical  definition,  and 
the  most  refined  micro-chemical  operations  to  make  them  visible  (Fig. 
72). 


Via.  72.— Connective  tissue  corpuscle  or  cell  from  the 
skin  of  Triton  tceniatus  x  5(30.  P,  prot"plasm  ;  K, 
nucleus;  1,  membrane  of  nucleus;  2,  intranuclear 
network  ;  3,  small  bodies  in  the  niicleus.  The  coarser 
threadlets  of  the  intranuclear  network  are  easily  seen  ; 
the  finer  threadlets  appear  with  this  power  as  mere 
points.     (Method  No.  1,  Appendix.) 


The  next  important  generalization  is  as  to  the  chemical  nature  of 
protoplasm.  Loose  expressions  were  much  in  vogue  eight  or  ten  years 
ago,  regarding  this  aspect  of  the  subject.  Life  was  said  to  be  identified 
with  a  little  albuminous  matter,  containing  phosphorus — protoplasm 
was  merely  a  drop  of  living  albumin — and  the  conception  one  Avas 
offered  of  albumin  was,  that  it  was  a  substance  like  a  little  white  of  egg. 
But  micro-chemistry,  and  a  study  of  the  chemical  reactions  of  living 
matter  have  effected  a  revolution  in  scientific  opinion.  It  is  evident 
that  living  protoplasm  cannot  be  analyzed.  The  attempt  at  analysis  by 
the  application  of  any  reagents,  or  by  the  use  of  physical  agencies,  such 
as  heat  or  electricity,  causes  it  to  fall  to  pieces;  only  the  fragments  re- 
main, whilst  the  peculiar  properties  which  we  associate  with  the  living 
state  have  vanished.  We  can,  however,  gather  up  these  fragments  and 
determine  their  chemical  nature.  They  are  found  to  consist  of  water,  of 
substances  having  the  character  of  the  albumins,  of  nitrogenous  matters 
rich  in  phosphorus,  of  fats,  of  carbo-hydrates,  such  as  glycogen  (animal 
starch)  and  glucose,  of  bodies  that  behave  like  ferments,  and  of  mineral 
matters,  such  as  chlorides,  sulphates,  and  phosphates  of  the  alkalies, 
and  of  the  alkaline  earths.  Thus  protoplasmic  stuff  is  seen  to  have 
i\  highly  complex  chemical  constitution.     (See  p.  26.) 

Let  us  return  to  the  cell.  During  the  last  ten  or  twelve  years,  and 
especially  during  the  last  three  or  four  years,  important  advances  have 
been  made,  more  especially  as  to  the  structure  of  the  nucleus  and  the 
functions  which  it  performs  in  the  reproductive  processes  of  the  cell. 
It  is  at  this  stage  that,  if  one  wishes  to  appreciate  the  true  position  of 


HISTORICAL  INTRODUCTION.  207 

the  cell  doctrine  at  the  present  time,  he  must  study  the  mode  of  the 
genesis  of  cells,  starting  with  the  changes  in  the  ovum  before  and 
after  fecundation.  Before,  however,  entering  on  this  difficult,  though 
profoundly  interesting,  subject,  let  us  turn  our  attention  to  the  re- 
markable observations  that  have  recently  been  made  on  the  structure 
of  the  nucleus,  beginning  with  the  appearance  of  a  work  by  Professor 
W.  Flemming,  of  Kiel,  in  1882.  In  this  work  Flemming  gives  a  his- 
torical account  of  previous  observations,  and  he  applies  a  new  nomen- 
clature to  the  different  parts  of  the  nucleus  that  can  be  revealed  by 
high  powers.  He  says  that  three  substances  exist  in  a  fully  formed 
nucleus — first,  &  reticular  network  of  fine  fibres;  second,  nucleoli;  and  third, 
a  nuclear  fluid  or  intermediate  substance,  the  whole  being  surrounded 
by  a  membrane — the  membrane  of  the  nucleus.  The  netAvork  he  calls 
karyomiton  {Kapvov,  a  kernel,  /xiros,  a  thread),  as 
opposed  to  the  hjtomiton  (kvtos,  a  cell),  or  net- 
work in  the  body  of  the  cell.  The  meshes  of  the 
network  vary  in  size — they  are  sometimes  uniform, 
sometimes  irregular,  and  they  often  present  nodo- 
sities or  swellings  at  the  points  where  the  fibres 
interlace.  The  fibres  forming  the  network  are 
fixed  by  acids,  chloride  of  gold  and  alcohol,  so  as 
to  become  more  apparent.  The  substance  forming  embryo"  of  H^rophiilfs 
the  fibres  has  a  strong  affinity  for  colouring  IviZ'r pc, "'frotopi^tm: 
matter,  and  on  account  of  this  property  Flemming  ^'CSXeld "r  at' 
has  termed  it  chronmtin;  but  it  is  important  to  dtoe^loiSasm^ 
note  that  this  word  has  more  of  a  morphological 
than  of  a  chemical  significance,  and  does  not  involve  any  theory  as  to 
its  chemical  character.  Flemming  has  also  corroborated  an  observation 
first  made  by  Balbiani  that  the  fibres  of  chromatin  in  the  nuclei  of  the 
salivary  cells  of  the  larva  of  Chironomus  (a  Tipula,  an  insect  resembling 
a  gnat)  show  a  transverse  striation,  indicating  the  existence  of  segments 
of  diflerent  constitution  (Fig.  73). 

In  the  meshes  of  the  reticulum  lie  one  or  more  nucleoli,  small  portions 
of  nuclear  substance  of  different  constitution  from  that  of  the  reticulum 
or  of  the  nuclear  fluid.  They  are  not  to  be  regarded,  however,  as 
variable  fragments  of  nuclear  matter,  but  as  specific  products,  the 
result  of  those  molecular  actions  of  which  the  nucleus  is  the  seat. 
Flemming  holds  that  these  minute  structures  have  probably  a  deter- 
minate physiological  purpose.  Further,  he  states  that  there  are  dif- 
ferences between  the  nucleoli  of  the  same  nucleus,  classifying  the  larger 
and  more  regular  in  appearance  as  principal  nucleoli,  and  the  others  as 
accessory  nucleoli.     There  are  also  differences  between  the  nucleoli  of 


208  THE  PIIYSIOLOUY  OF  THE  TISSUES. 

different  cells,  more  especially  as  regards  the  existence  in  them  of 
minute  vacuoles,  or  round  spaces.  He  has  also  noticed  extremely  slow 
changes  of  form  in  the  nucleoli  of  certain  living  cells.  In  the  changes 
attending  the  division  of  the  nucleus  in  cell  division,  the  nucleoli  dis- 
appear, and  after  cell  division  they  reappear.  Flemming  is  of  oi)inion 
that  their  disappearance  arises  from  a  distribution  of  their  substance 
through  the  nucleus,  and  that  their  reappearance  or  genesis  is  a  function 
of  the  reticular  network.  He  has  also  observed  that  in  general,  but  not 
ahvays,  the  absolute  volume  of  the  nucleoli  is  j^roportional  to  the 
volume  of  the  nucleus. 

Flemming  has  observed  in  the  great  majoritj'-  of  nuclei  a  limiting 
memhrmie,  or  envelope,  and  he  distinguishes  in  some  cases  an  achromatic 
and  a  chromatic  membrane.  The  first — the  achromatic — so  termed 
because  it  does  not  stain  readily,  is  found  in  the  germinal  vesicle  or 
nucleus  of  many  ova.  The  chromatic  membrane  is  sometimes  perforated 
by  small  holes,  and,  according  to  Frommann,  Klein,  and  others,  an 
anastomosis  of  the  intranuclear  and  intracellular  networks  may  thus 
exist.  ^ 

Lastly,  the  nuclear  fluid  is  probably  a  solution  of  saline  matters,  along 
with  albuminous  and  other  organic  constituents. 

As  I  have  detailed  these  characters  according  to  the  descriptions  of 
Flemming,  it  will  have  been  evident  that  the  nucleus  is  not  so  simple  a 
structiu-e  as  it  has  been  hitherto  supposed.  These  observations  have 
been  repeated  by  many  of  the  most  careful  workers,  by  men  such  as 
Strasburger,  Leydig,  Pfitzner,  E.  van  Beneden,  Carnoy,  Frommann, 
Klein,  Brass,  furnished  with  the  best  microscopic  appliances,  and 
thoroughly  familiar  with  the  interpretation  of  microscopical  appear- 
ances. It  is  not  surprising,  however,  that  whilst  all  admit  that  a  new 
world  of  real  phenomena  has  been  opened  up,  there  are  considerable 
differences  of  opinion,  and  a  good  deal  of  confusion,  from  the  unfor- 
tunate tendency  to  the  introduction  by  each  new  observer  of  his  own 
nomenclature.  Recently,  Professor  van  Bambeke,  of  Gand,  in  Belgium, 
has  attempted  to  introduce  order  into  this  chaos  by  a  systematic  study 
and  classification  of  the  observations  and  views  of  different  authors. 

Thus  with  reference  to  the  nature  of  the  fibrous  appearance  seen  in 
nuclei,  observers  may  be  arranged  in  two  classes  :  1st,  those  who  follow 
Flemming  in  regarding  it  as  a  reticulum  or  network,  namely  Pfitzner, 
Eetzius,  Leydig,  Van  Beneden,  etc. ;  and  2nd,  those  who  hold  the  reti- 
culated appearance  to  be  due  to  the  presence  in  the  nucleus  of  a  coiled- 

^  It  is  unfortunate  t^at  the  terms  chromatic  and  achromatic  have  been  intro- 
duced in  the  terminology  of  nuclear  structures,  as  these  words  have  a  definite 
meaning  in  physical  science,  employed  in  describing  optical  phenomena. 


HISTORICAL  INTRODUCTION.  209 

up  filament,  namely,  Strasburger,  Balbiani,  Carnoy,  etc.  Most  of  those 
in  the  first  category  agree  in  the  general  description  of  a  reticulum,  but 
they  differ  as  to  terminology,  and  as  to  certain  minute  details  of 
structure  which  each  observer  believes  he  has  demonstrated.  Thus,  E. 
van  Beneden,  in  his  researches  on  the  fecundation  of  an  intestinal  worm 
found  in  the  horse,  Ascaris  megalocephala,  describes  the  nucleus  as  con- 
sisting of  a  membrane,  mthin  which  there  is  a  network  of  chromatin, 
containing  in  its  meshes  a  fluid  substance.  The  whole  of  this  mass 
forming  the  membrane  and  reticulum  he  calls  nucleoplasm,  and  he 
describes  it  as  consisting  of  two  portions :  1st,  an  achromatic  substance 
arranged  in  fine  moniliform  filaments;  and,  2nd,  a  chromatic  substance 
which  is  imbibed  by  the  membrane  and  by  the  reticulum,  and  which 
also  fills  the  meshes.  Further,  he  supposes  that  each  fibre  or  filament 
consists  of  numerous  minute  bodies,  nucleomicrosomata  (readily  stained), 
between  which  the  chromatic  substance  exists,  and  the  more  elongated 
fibrils  he  terms  nuclear-threads. 

Strasbiu"ger  also  regards  a  nucleus  as  consisting  of  nucleoplasm  (or 
karyoplasma),  in  which,  as  in  kytoplasma,  there  are  two  matters  :  the 
nucleomicrosomata,  taking  up  pigment,  and  the  nucleohyaloplasma,  which 
is  not  stained.  The  nucleoplasma  is  an  elongated  filament,  of  variable 
thickness,  crossing  in  loops  in  all  directions,  and  thus  gi^ang  rise  to  the 
reticulated  appearance. 

Arnold  Brass,  of  Marburg,  takes  a  somewhat  diff"erent  view  of  the 
constitution  of  the  chromatin  filament.  He  says  it  is  the  seat  of  meta- 
morphoses by  which  it  may  vary  much  in  consistence,  so  that  sometimes 
it  may  be  squeezed  out  of  nuclei  into  long  filaments.  Further,  he  holds 
that  the  chromatin  filament  is  not  one  substance,  but  a  mixture  of  various 
substances,  as  he  does  not  find  the  reagents  he  employs  act  upon  it 
uniformly.  If  the  substance  or  substances  be  in  a  state  of  solution, 
then  there  may  be  no  appearance  of  structure  in  the  nucleus,  and  it 
may  be  called  a  homogeneous  nucleus  (a  condition  rarely  met  with) ;  or 
they  may  appear  in  the  form  of  granules  or  filaments  which  may  either 
anastomose  or  form  one  long  coiled-up  filament. 

Carnoy  of  Louvain  describes  a  nucleus  as  a  kind  of  little  cell  con- 
taining a  cord  or  coiled  filament  of  nuclein.  Each  nucleus  has  then  (1) 
a  protoplasmic  body,  and  (2)  a  portion  formed  of  nuclein,  which  is  the 
chromatin  of  Flemming.  He  also  terms  the  protoplasmic  portion  karyo- 
plasma, a  hyaline  mass,  homogeneous  in  appearance,  and  having  granules 
interspersed.  Carnoy  sums  up  his  conclusions  as  to  the  second  con- 
stituent, the  nuclein  (or  chromatin),  in  the  following  propositions — 

1.  In  typical  nuclei  the  element  nuclein  presents  a  filamentous  form  ;  it  is  com- 
posed of  a  continuous  or  coiled  filament. 
I.  O 


210 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


2.  The  chromatic  reticulum  of  Flemming  is  only  an  appearance  due] to  the  regular 
crossing  of  its  convolutions,  rarely  to  their  temporaiy  union  (Fig.  7-4). 


Fia.  7-i. — Two  nuclei  of  the  epidermis  of  Salamandra  maculata.  A,  nucleus 
at  rest :  the  nuclear  filament  forms  a  network  by  the  convolutions  being 
fused  so  as  to  present  thickenings,  nr.  A,  nucleus  before  division,  or 
karyokinetic  process.  The  filament  seen  in  A'  is  now  swollen,  and  its 
convolutions  are  separated  so  that  one  long  coiled  filament  is  seen. 

3.  The  nuclear  filament  is  subject  to  profound  changes.     Thus  it  may  he  broken 
into  fragments,  or  even  into  spherules,  or  it  may  dissolve  and  totally  disappear. 


/2    / 


Fio.  75.— Giant  cells  of  the  marrow  of  a  rabbit,  pr,  delicately  reticulated 
protoplasms,  with  a  rich  enchylema  or  juice  ;  n,  irregularly  formed 
nucleus  containing  a  filament  of  nucleiu,  coiled  in-egularly  and  in  a  com- 
plex manner,  so  as  to  form  a  network  by  the  points  at  which  the  fila- 
ments cross  being  fused  together. 

■4.  The  nuclear  filament  is  structiiral.  One  may  distinguish  a  wall,  a  tube,  and 
contents.     Even  the  contents  may  be  organized,  appearing  in  the  form  of  discs,  etc. 

0.  Usually  the  nuclear  filament  does  not  occupy  a  determinate  position,  but  it 
may  be  localized  towards  the  centre  of  the  nucleus  forming  a  nucleolus. 

The  karyoplasma,  or  protoplasmic  portion,  of  Carnoy,  like  the  kyto- 
plasma  (cellular  plasma),  is  thus  formed  of  a  reticulum  and  an  enchylema 
()(wAo?,  juice  or  moisture  of  plants,  afterwards  applied  to  animal  fluids, 
such  as  chyle),  a  substance  in  the  meshes,  or  the  intermediary  substance, 
or  nuclear  fluid  of  other  authors  (Figs.  75  and  76). 

One  other  research  it  is  important  to  notice  as  it  relates  to  the 
chemical  nature  of  nuclear  matter.  In  1871,  Miescher  found  in  the 
nuclei  of  cells  a  substance  to  which  he  gave  the  name  nuclein.  (Sec 
p.  78.)     In  1882  and  1883,  Zacharias  repeated  Miescher's  observations 


HISTORICAL  INTRODUCTION. 


211 


on  nuclein,  only  using  the  methods  of  micro-,  instead  of  macro-chemistry, 
and  he  arrived  at  the  important  conclusion  that  two  chemical  matters 


Fig.  76. — Cell  and  typical  nucleus  of  the  intestinal  epithelium  of  a 
maggot,  mc,  cellular  membrane  ;  pc,  cellular  protoplasm  ;  observe 
the  radiating  reticulum  with  the  enchylema  or  juice  enclosed  in  the 
meshes  ;  ran,  membrane  of  the  nucleus  ;  -pn,  plasma  of  the  nucleus  ; 
here  observe  also  a  reticulum  and  plasma,  distinct  from  those  of  the 
protoplasm  ;  hn,  continuous  nuclear  thread  or  filament,  contracted  in 
the  centre  of  the  nucleus  and  showing  numerous  loops. 

exist — (1)  nudein,  which  gives  the  same  reactions  as  the  soluble  nuclein 
of  Miescher ;  and  (2)  plastin,  a  matter  which  gives  different  reactions. 
Further,  he  states  that  nuclei  contain  a  fundamental  substance  nearly 
related  to  protoplasm,  which  is  chiefly,  if  not  wholly,  plastin,  whilst 
chromatin  is  the  same  substance  as  nuclein.  He  supposes  also  that  the 
matters  termed  chromatin  by  Flemming  are  probably  mixtures  of  plastin 
and  nuclein. 


If  we  attempt  to  make  a  critical  estimate  of  the  result  of  these 
numerous  investigations,  we  may  reach  the  following  conception  of  a 
nucleus  :  (1)  It  is  a  small  round  or  oval  body,  having  an  envelope  or 
membrane,  and  containing  a  reticulum  or  net-work,  in  the  meshes  of 
which  there  is  a  semi-fluid  matter ;  (2)  in  some  cases,  possibly  in  all,  at 
a  definite  period  in  the  life  of  the  nucleus,  instead  of  a  reticulum  there 
may  be  a  coiled  filament  or  a  series  of  filaments,  not  anastomosing, 
floating  in  a  nuclear  fluid ;  (3)  to  the  matter  forming  the  reticulum,  or 
forming  the  filament  or  filaments,  the  name  chromatin  may  be  given, 
inasmuch  as  this  readily  takes  up  colouring  matters ;  but  as  staining 
fluids  do  not  stain  the  whole  of  the  chromatin  filament  uniformly,  it  is 
highly  probable  that  another  substance  exists  in  the  chromatin  filament, 


212  THE  PHYSIOLOGY  OF  THE  TISSUES. 

and  in  the  membrane  of  the  nucleus,  Avhich  may  be  proAdsionally  termed 
achromatin,  and  which  possibly  forms  the  organic  basis  of  the  whole 
structure  ;  (4)  to  the  semi-fluid  matter  the  name  of  nuclear  fluid  may  be 
given  ;  (5)  in  the  meshes  of  the  reticulum,  or  in  the  coils  of  the  filament, 
there  may  be  one  or  more  small  bodies  (nucleoli)  which  appear  to  be  of 
the  same  nature  as  the  chromatin  filament,  but  which,  from  their  uniform 
presence  in  the  nuclei  of  certain  cells,  and  from  their  behaviour  in  the 
process  of  cell  division,  are  probably  portions  of  nuclear  matter  having 
a  special  physiological  significance,  at  present  only  conjectural ;  and 
(6)  there  is  no  absolute  proof  that  there  is  any  connection  between  the 
chromatin  filaments  in  the  nucleus  and  the  net-work  of  fibres  in  the  cell 
substance  outside  the  nuclear  wall. 

Such  being  the  structure  of  the  nucleus,  the  next  and  most  important 
question  is,  what  part  does  it  perform  in  the  process  of  cell  division  ? 
It  was  in  1841  that  Martin  Barry  first  observed  that  the  division  of  cells 
Avas  associated  Avith  division  of  the  nucleus,  and  for  many  years  it  Avas 
supposed  that  this  Avas  simply  a  fission  of  the  nucleus,  folloAved  by  a 
fission  of  the  Avhole  cell,  so  that  the  daughter  nucleus  was  contained  in 
the  neAv  cell.  It  Avas  also  obserA^ed  that  in  many  tissues  nuclei  might 
apparently  divide  Avithout  fission  or  division  of  the  matter  in  Avhich  they 
existed,  so  that  certain  cells  or  tissues  contained  several  nuclei.  The 
simple  diAdsion  of  the  nucleus,  AAdthout  any  changes  occurring  in  that 
structiure,  and  folloAved  by  division  of  the  protoplasm  of  the  cell,  is 
called  akinetic,  or  direct  diAdsion  {kIv'hh,  to  move,  to  set  agoing).  A 
better  term,  I  think,  is  that  suggested  by  Carnoy,  karyostenosis  (Kapvov, 
a  kernel ;  o-revojo-ts,  a  being  straitened ;  a-revw,  to  make  narroAv).  This 
mode  of  diAdsion  has  been  observed  by  RauAder  and  Lavdowski  in  the 
formation  of  leucocytes,  epithelial  cells,  certain  fat  cells,  and  it  appears 
to  be  the  mode  of  diAdsion  of  the  parenchymatous  cells  of  plants,  and 
of  some  algae  and  infusoria  (Fig.  77). 

The  other  mode  of  division,  sometimes  called  indirect  division,  or 
karyokinesis,  a  term  first  used  by  Schleicher,  Avas  first  described  by 
Professor  Biitschli,  of  Heidelberg,  in  1876,  as  occurring  in  the  cells  of 
the  testis  of  Blatta  germanica,  in  tAvo  blastodermic  cells  of  Musca  vomitoria, 
and  finally  in  the  parthenogenetic  egg  of  Aphis.  Since  then,  this  mode 
of  diAdsion  has  been  found  by  others  in  many  organisms,  both  plant  and 
animal.  It  appears  to  be  common  in  the  vertebrates,  and  may  be 
readily  demonstrated  in  the  epidermal  cells  of  amphibians.  The  pro- 
cess may  be  described  as  folloAvs  (Fig.  78),  using  the  terms  suggested  by 
Flemming — The  chromatin  of  the  nucleus  is  increased,  and  is  developed 
into  a  complexly  coiled  thread,  called  the  spirem  {cnrdprnxa,  a  Avreath,  a 


HISTORICAL  INTRODUCTION. 


213 


coil  or  spire),  while  the  nucleoli  and  the  membrane  of  the  nucleus  dis- 
appear.    The  thread  is  next  divided  into  portions  which  assume  the 


Fig.  77. — Direct  cell  division,  or  karyostenosis.  a,  fully 
formed  cell ;  &,  beginning  of  division  of  nucleus  and  also 
of  cell  substance  ;  c,  division  of  nucleus  and  of  cell  sub- 
stance complete  ;  d,  formation  of  two  new  cells. 

form  of  loo-ps.  These  are  at  first  placed  irregularly,  but  they  are  soon 
arranged  in  such  a  way  that  the  tops  of  the  loops  are  turned  towards 
the  clear  middle  part  of  the  nucleus,  while  the  free  ends  of  the  loops 
are  directed  towards  the  circumference.  This  form  is  termed  the  ast&r 
[dcTT-qp,  a  star),  or  garland.  The  loops  are  next  divided  in  the  direction 
of  their  length,  whereby  their  number  is  doubled,  but  the  loops  them- 
selves become  thinner.  Then  the  loops  are  collected  towards  the 
middle  or  equator  of  the  nucleus,  so  as  to  form  a  flat  body  around  it, 
called  the  equatorial  plate.  Shortly  afterwards  the  loops  separate  into 
two  groups,  each  group  retreating  towards  the  pole  of  the  nucleus, 
giving  rise  to  the  barrel-form  or  loitlwde  (TndwSrjs,  like  a  cask).     The 


Pig.  78. — Views  of  the  various  stages  of  karyokinesis,  or  division  of  the  nucleus 
from  a  section  of  the  epidermis  of  Triton  toeniatus,  x  560  d.  1.  Two  epithelial  cells, 
in  which  are  seen  the  nucleus,  the  membrane  of  the  nucleus  Icm,  and  the  dark- 
coloured  net-work.  2.  Disappearance  of  the  nuclear  membrane — Spirem.  3.  Nuc- 
lear threads  in  groups  and  having  the  loops  dividing  at  the  centre  c,  or  at  the 
periphery  p.  4.  Monaster,  in  which  the  loops  are  directed  to  the  centre.  5.  The 
loops  are  thin  and  very  numerous,  in  consequence  of  division.  0.  Equatorial 
Plate.  7.  Barrel-form.  S.  Di/aster.  9.  Contraction  of  the  protoplasm  of  the  cell ; 
both  the  neighbouring  cells  show  nuclei,  the  net-work  in  which  is  not  distinguish- 
able. 10.  Complete  division  of  the  cell,  the  nuclei  in  which  have  not  yet  returned 
to  the  original  resting  condition  seen  in  1.    (Method  No.  2,  Appendix.) 

groups  of  loops  now  separate  still  further,  and  having  the  closed  ends 
of  the  loops  towards  the  poles,  give  rise  to  a  double  star,  or  dyaster. 


•214  THE  PHYSIOLOGY  OF  THE  TISSUES. 

Then  there  begins  at  the  equator  of  the  cell  a  division  of  the  protoplasm, 
which  leads  to  its  complete  separation  into  two  equal  parts.  The  groups 
of  loops  again  become  irregularly  coiled  up  like  a  clew,  giving  rise  to  an 
appearance,  called  dispirem,  and  finally  these  remarkable  movements 
subside,  and  the  threads  of  chromatin  again  assume  the  form  and 
arrangement  seen  in  a  nucleus  in  repose.  The  duration  of  this  process 
has  been  ascertained  to  be  as  short  as  half  an  hour  in  man,  whilst  in 
amphibians,  where  it  is  most  easily  studied,  it  may  occupy  five  hours. 
According  to  Carnoy,  several  of  these  changes  may  be  omitted,  and  he 
states  that  there  are  many  gradations  between  the  karyostenotic  and  the 
karyokinetic  modes  of  nuclear  division. 

Chap.  II.— THE  ORIGIN  OF  THE  TISSUES. 

Having  thus  endeavoured  to  give  a  concise  account  of  the  modern 
vieAvs  held  as  to  the  nature  of  protoplasm,  cells,  and  nuclei,  we  now 
proceed  to  a  description  of  the  changes  that  have  been  observed  during 
the  process  of  fecundation  by  Avhich  the  primitive  cells  of  the  body  are 
formed,  because,  as  previously  remarked,  the  phenomena  of  fecunda- 
tion and  those  of  cell  division  ought  to  be  studied  together  if  one  desires 
a  comprehensive  Adew  of  the  subject.  It  is  of  course  well  known  that 
fecundation  consists  in  the  blending  of  the  male  and  female  elements. 
Strictly  speaking  it  may  be  now  defined  as  the  blending  of  two  nuclei, 
one  derived  from  the  female,  and  the  other  from  the  male  parent  cell. 
The  cell  thus  formed  divides  repeatedly  by  fission  so  as  to  form  the 
embryonic  cells  from  Avhich  all  tissues  are  derived. 

1.  The  Male  Elements  or  Spermatozoa. — The  male  element  is  represented 
by  the  spermatozoid,  first  discovered  by  Louis  Ham,  a  pupil  of  Leeuwen- 
hoek,  in  1677,  and  the  spermatozoids  of  mammals,  birds,  fishes,  molluscs, 
and  of  certain  insects  Avere  described  by  the  latter.  They  were  then, 
and  for  many  years  after,  termed  animalcules,  but  Buffon,  Avith  more 
insight,  applied  the  name  living  molecules.  It  was  many  years  before 
the  idea  of  their  individuality  as  specific  organisms  was  abandoned,  and 
it  was  not  until  the  observations  of  Prevost  and  Dumas  in  1824,  of 
VonKolliker  in  1841,  and  of  NeAAq^ort  in  the  year  1850,  that  their  true 
position  as  constituent  elements  of  the  body  Avas  recognized.  Their 
development  was  first  traced  to  some  extent  by  Von  Siebold  and 
Leuckart  in  1836 ;  in  1846,  Von  Kolliker  asserted  that  they  were 
essentially  nuclei  developed  in  certain  cells  of  the  testes.  At  first.  Von 
Kolliker  held  that  they  were  developed  in  the  interior  of  nuclei,  but 
as  Henle,  in  1854,  shoAved  that  not  only  the  nucleus  but  part  of  the 
protoplasm  of  the  cell  (forming  the  tail)  took  part  in  their  evolution, 


THE  ORIGIN  OF  THE  TISSUES. 


215 


Von  Kolliker,  in  1851,  modified  his  opinion  to  the  extent  of  stating  that 
the  whole  nucleus  entered  into  the  formation  of  the  spermatozoid.  In 
1865,  Schweigger-Seidel  went  a  step  further,  and  asserted  that  the 
spermatozoids  were  not  merely  nuclei,  but  were,  on  the  contrary,  entire 
cells,  each  carrying  a  vibratile  cilium. 

The  spermatozoids  are  developed  in  the  two  glands  termed  the  testes, 
the  general  structure  of  which  is  shown  in  Fis.  79. 


Fig.  79. — Transverse  section  of  the  testis  of  a  newly-torn  boy,  10  times 
magnified — 1,  tunica  albuginea  ;  2,  tunica  vasculosa  ;  3,  corpus  Highmorianum 
or  mediastinum  testis,  containing  the  rete  testis  ;  4,  septa  of  the  testis  ; 
5,  lobules,  consisting  of  convoluted  seminiferous  tubules  ;  6,  straight  tubes  or 
rasa  recta,  passing  into  the  rete  testis  ;  7,  globus  major  of  epididymis  ;  8,  vas 
deferens,  or  excretory  duct  of  testis  ;  9,  blood-vessels.  (Method  No.  3,  Ap- 
pendix.) 

The  essential  structures  in  the  testis  are  the  tubuli  seminiferi,  long  con- 
voluted tubes  lined  with  epithelial  cells  in  which  the  spermatozoids  are 
developed.     Sections  of  these  tubules  are  seen  in  Fig.  80. 

It  has  been  found  difficult  to  trace  the  origin  of  the  spermatozoids  in 
the  cells  in  the  tubes  of  the  testicle,  and  the  question  cannot  even  now 
be  regarded  as  settled.  Von  Kolliker,  in  1856,  described  two  kinds  of  cells, 
an  outer  layer,  with  large  nuclei  and  nucleoli,  and  an  inner  layer  of 


216 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


smaller  cells,  which  Avere  the  true  sperm  cells.     The  sperm  cells  Ijccame 
cysts  in  which  the  spermatozoids  were  developed.      In  1871,  Merkel 


^'^.di'!i^^^ 


B 

Fig.  80. — Transverse  sections  throiigli  tubuli  seminiferi  of  the  testis  of  an  ox,  SO  times 
magnified.  A,  two  transverse  sections  of  the  smaller  tubules — a,  tubule  in  a  state  of 
rest ;  6,  in  a  state  of  activity ;  c,  spei-matoblasts  ;  (/,  nuclei  of  indifferent  seminal 
cells  deeply  coloured.  B,  transverse  section  of  a  tubule  in  an  active  condition — (j, 
group  of  young  si^ermatozoids,  connected  with  the  spermatoblast.  (Method  4,  Ap- 
pendix.) 

described  a  ramified  set  of  cells  in  the  tubules  which  formed  a  kind  of 
support  or  framework  on  which  the  spermatozoids  were  formed,  and  in 
the  same  year,  von  Ebner  developed  this  idea  and  figiu'ed  peculiar 
branching  structures  on  which  the  spermatozoids  originated.  These 
outgroAvths  from  the  living  membrane  of  the  seminiferous  tubules  he 
called  spermatoUasts.  Each  spermatoblast  has  a  number  of  rounded 
lobules,  and  each  lobule  gives  rise  to  a  spermatozoon,  the  nucleus 
lengthening  to  form  part  of  the  head,  while  a  thin  film  of  protoplasm 
forms  the  tail.     As  the  young  spermatozoids  develop,  they  are  at  first 


Fig.  si. — Spermatogenesis  (after  Landois).  I.  cross  section  through  a 
seminal  tubule  ;  II.  unripe  spermatoblast,  with  blunt  rounded  laplets, 
the  young:  sperms ;  III.  spermatoblast  with  ripe  ciliated  heads ;  IV. 
spermatoblast  after  separation  of  spermatozoids. 

closely  connected  with  the  spermatoblast,  but  Avhen  set  free  they  roll  off' 
into  the  tubule  (Fig.  81).      In  1875,  Sertoli  described  the  development 


TEE  ORIGIN  OF  THE  TISSUES. 


217 


of  spermatozoids  in  the  Elasmobranclis  (sharks,  rays,  etc.).  He  traced 
the  invagination  of  the  primitive  germinal  epithelium  into  the  under- 
lying stroma,  so  as  to  form  a  follicle,  and  in  certain  of  the  cells  of  this 
follicle — "mother  cells" — the  nucleus  divided  so  as  to  form  a  number 
of  minute  bodies,  each  of  which  became  a  spermatozoid.  Yon  la  Valette 
St.  George  examined  spermatogenesis  in  the  vertebrates  and  published 
his  results  in  1878.  According  to  him,  two  sets  of  cells  exist  in  the 
tubules;  one  set,  like  young  ova,  he  calls  spermaiogonia ;  these  divide 
into  numerous  smaller  cells,  spermatocijtes,  each  of  which  may  form  a 
spermatozoid,  as  in  mammals,  or  they  may  take  part  in  the  formation 
of  sujDporting  structures  or  envelopes  for  the  spermatozoids,  as  in  fishes 
and  amphibia ;  the  other  set  of  cells  does  not  take  any  part  in  spermato- 
genesis. Lastly,  Eenson,  in  1882,  describes  the  larger  cells  of  Yon  la 
Yalette  as  forming  cysts  called  spermatogemmce,  each  containing  a  number 
of  nematohlasts,   which   become   the    young    spermatozoids    (Fig.    82). 


Fig.  82.— Spermatogenesis  (after  Eenson).  1,  follicular  cells  ;  2,  spermatogemmM ; 
8,  4,  5,  6,  7,  8,  separate  nematoblasts,  developing  into  spermatozoa ;  9,  nema,to- 
blasts  grouped  on  supporting  cell ;  10  and  11,  successive  stages  of  the  penetration 
of  the  young  spermatozoa. 

These  nematoblasts,  when  liberated  from  the  cyst,  cluster  round  certain 
elongated  epithelial  or  supporting  cells,  similar  to  the  spermatoblasts  of 
von  Ebner,  and  become  biu-ied  in  the  protoplasm  until  their  full  de- 
velopment. They  may  even  penetrate  to  the  bottom  of  the  spermato- 
blast (supporting  cell),  but  this  structure  then  grows  outwards  and 
carries  the  spermatozoids  to  the  centre  of  the  seminiferous  tubule, 
where  they  are  finally  discharged. 

Many  other  views  have  been  offered,  but  those  which  I  have  detailed 
may  be  regarded  as  typical  expressions  of  opinion  on  this  difficult 
question.  It  is  evident  that  the  spermatozoon  is  a  highly  differen- 
tiated structiire,  requiring  specific  arrangements  for  its  maturation  and 
development  (Fig.  83). 

Spermatozoids  vary  much  in  form.  The  familiar  type  is  that  show- 
ing an  oval  head  and  a  long  filament  or  tail  (Fig.  84).  It  is  remarkable 
that  this  comparatively  simple  form  is  found  both  in  the  higher  and 
lower  groups.     Thus  it  is  met  with  in  the  sponge,  in  medusae,  in  tape- 


218 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


worms,  and  in  mammals   generally,   including   man.      On   the   other 
hand,  the  spermatozoa  of  various  intestinal  worms  (ascaris),  and  of 


Fig.  S3. — A,  I.?olated  elements  of  the  testis  of  an  ox. 
a,  seminal  germ  cells  ;  b,  spermatoblast ;  e,  indifferent 
seminal  cell ;  d,  torn  off  (?)  process  of  a  spermatoblast  ; 
e,  almost  finished  thread  with  a  remainder  of  proto- 
plasm near  the  middle.  B  and  C,  from  a  section  of 
testis  of  ox.  1,  Seminal  germ  cell ;  2,  spermatogemmse  ; 
3,  spermatoblast ;  4,  indifferent  seminal  cells  ;  x  240. 
(Method  No.  5,  Appendix.) 


Fio.  S4. — Spermatozoids 
of  man,  560  times  magni- 
fied. 1,  seen  from  sur- 
face ;  2,  from  the  edge ; 
8,  with  fine  filamentous 
tail  ;  4,  spermatozoid 
from  semen  of  ox.  a, 
head ;  b,  middle  por- 
tion ;  c,  tapering  end  of 
tail.  (Method  No.  6,  Ap- 
pendix.) 


arachnids,  are  irregular  in  shape,  like  amoeboid  corpuscles;  in  the  ne^vyts 
and  salamanders  the  tail  may  be  fringed  by  a  membrane,  and  in  many 
birds  the  tails  of  the  spermatozoids  are  of  enormous  length  (Fig.  85.) 

The  head  of  the  spermatozoon  is  of  special  physiological  importance 
because  it  is  the  part  containing  the  chromatin  (or  nuclein),  derived 
from  the  nucleus,  consequently  it  is  readily  stained  A^th  colouring 
matters.  The  tail  is  formed  of  protoplasm.  Some  have  described 
certain  small  nuclei  in  the  spermatoblasts  that  do  not  enter  into  the 
formation  of  the  spermatozoids,  and  in  accordance  ^vith  the  theory  to 
be  afterwards  mentioned,  that  all  cells  may  be  regarded  as  herma- 
phrodite, that  is  to  say,  as  containing  both  male  and  female  elements 
these  have  been  termed  female  nuclei.  This  is  a  very  doubtful  inter- 
pretation. 

In  man  the  head  of  the  s^Dermatozoon  is  from  3  to  5  /x  long,  and  2  to 
5  /A  broad  ;  the  middle  portion,  that  is  to  say,  im.mediately  behind  the 
head,  is  about  6  /x  in  length,  and  1  ix.  broad,  and  the  tail  is  from  40  to 
50  fx  long,  and  runs  out  to  a  fine  point  (Fig.  84). 

Spermatozoa  have  remarkable  powers  of  resistance.  The  sinuous  move- 
ments belong  to  the  tail,  which  pushes  the  head  before  it.  AMiile  the 
spermatozoids  are  in  the  testicle  these  movements  scarcely  exist,  and  it  is. 
only  when  they  reach  the  fluid  secreted  by  the  epididymis,  by  the 
vesiculce  seminales,  by  the  prostate  gland  and  by  Cowper's  glands,  that 
the  movements  become  active,  probably  owing  to  a  stimulating  action 
of  these  fluids.     The  movements  may  go  on  for  from  24  to  48  hours. 


TRE  ORIGIN  OF  THE  TISSUES.  219 

after  removal  of  the  spermatozoids  from  the  body,    under  favourable 
circumstances.     Water  arrests  the   movements,    but  they  may  recom- 


'<   ^\  <  f  ^^  ^M  '}y  '0'^ 


Fig.  85. — Forms  of  spermatozoa — 1,  sponge;  2,  merJusa;  3,  botkrioce- 
phalv.s  (tape  worm)  ;  4,  cleta  (chsetopod) ;  5,  ascaris  (thread  worm)  ; 
6,  moina  (daphnid) ;  7,  crab  ;  8,  lobster  ;  9,  10,  11,  plagiostoma 
forms  with  elongated  nucleus  ;  12,  salamander ;  13,  ray  ;  14,  man ; 
15,  cobitis  (fish ) ;  16,  mole. 

mence  on  the  addition  of  very  weak  alkaline  fluids.     Even  extremely 
weak  acids  at  once  kill  the  spermatozoids. 

2.  The  Female  Elements  or  Ova. — We  must  now  turn  our  attention  to 
the  nature  of  the  ovum  or  egg.  This  is  found  in  a  special  organ  termed 
the  ovary,  an  organ  for  many  years,  from  the  time  of  Galen  to  the 
middle  of  the  17th  century,  described  as  testis  muliebris.  De  Graaf,  in 
1672,  was  the  first  to  describe  the  ovary  carefully.  He  described  the 
vesicles  that  bear  his  name,  the  Ghxiafian  vesicles,  which,  however,  he 
regarded  as  ova,  and  he  stated  that  ova  were  structures  to  be  found 
throughout  the  whole  range  of  the  animal  kingdom.  He  also  observed 
the  ovum  itself  in  the  rabbit.  Little  progress,  however,  was  made  till 
1825,  when  Purkinje  discovered  the  germinal  vesicle  in  the  ovum  of  the 
common  fowl.  Then  in  1827,  Von  Baer  traced  the  changes  in  the 
ovum  from  the  uterus  back  to  the  Graafian  vesicle.  Soon  afterwards, 
Coste  showed  that  Purkinje's  vesicle  occurred  in  the  mammalian  ovum, 
and  in  18-36,  Wagner  discovered  the  germinal  spot,  sometimes,  therefore, 
called  Wagner's  spot.  From  this  date  until  the  last  few  years  little 
progress  was  made  in  the  study  of  the  minute  structure  of  the  ovum^ 
and  it  Avas  described  as  a  typical  cell,  having  a  cell  wall,  the  zona 
Ijellucida,  or  vitelline  membrane,  surrounding  the  contents,  or  yolk,  in 
which  lay  embedded  the  germinal  vesicle,  or  nucleus,  which  had  a 
nucleolus — the  germinal  spot.  The  ovum  has  shared,  however,  in  the 
recent  progress  made  in  the  study  of  the  structure  of  the  cell  and  the 
structure  of  nuclei,  and  now  we  know  that  the  nucleus  shows  the 
threads  of  chromatin,  or  a  reticulum  with  wide  and  irregularly  formed 
meshes  (Fig.  86). 


220 


TEE  PHYSIOLOGY  OF  THE  TISSUES. 


The  ovaries  consist  of  connective  tissue  and  of  a  ii'landular  substance. 


Fig  S6. — Ovum  of  rabbit  from  an  egg  follicle  2  mm.  in  dia- 
meter, zp,  zona  pellucida,  having  at  the  top,  cells  of  the 
germinal  epithelium  ge.  The  yolk  shows  corpuscles  of 
deutoplasm  d.  In  the  germinal  vesicle  f/v  is  the  nuclear  net- 
work nn,  with  a  large  nucleolus  the  germinal  spot,  jr«. 

The  connective  tissue,  forming  the  stroma  of  the  ovary,  is  arranged  in 
various  strata,  and  contains  numerous  vessels  (Fig.  87). 


^^, 


<y- 


Fio.  87. — Transverse  section  of  the  ovary  of  a  girl  8  years  old,  10  times  magnified. 
1,  germ  epithelium  ;  2,  tunica  albuginea,  still  weakly  developed  ;  ?.,  outermost 
zone  of  the  cortical  substance,  containing  numerous  small  follicles  ;  4,  larger 
follicle ;  5,  inner  portion  of  the  cortical  substance  ;  li,  central  substance,  or 
stroma,  with  numerous  arteries  ;  7,  follicle,  with  the  outer  wall  cut  off ;  8, 
larger  follicle,  the  discus  proligerus  of  which  has  not  been  exposed  in  the  section ; 
9,  hilum  of  the  ovary,  containing  wide  veins.     (Method  Xo.  7,  Appendix.) 


TEE  ORIGIN  OF  THE  TISSUES. 


221 


In  the  outer  part  of  tlie  stroma  is  the  so-called  glandular  substance, 
which  contains  numerous  small  follicles,  about  36,000  in  the  human 
being,  each  having  in  it  a  small  ovum  or  egg.  It  is  remarkable  that  at 
an  early  period  of  intra-uterine  life  vast  numbers  of  ova  are  found  in  the 
ovary,  even  during  its  development.  Many  of  these  never  come  to 
maturity.  Most  of  these  follicles  are  extremely  small,  measuring  not 
more  than  40  jx.  The  larger  follicles  in  which  the  ova  reach  maturity 
lie  much  deeper.  The  upper  surface  of  the  ovary  is  covered  with  germ 
epithelium,  consisting  of  small,  short,  cylindrical  cells.  In  the  embryonic 
period,  the  ova  pass  through  only  the  first  stage  of  development,  and 
their  further  development  takes  place  in  the  Graafian  vesicles.  In  the 
foetal  period,  and  even  after  birth,  we  find  between  the  cylindrical  cells 
of  the  germ  epithelium  large  roundish  cells,  provided  with  a  mxcleus 
and  nucleolus.  These  are  the  pimordial  ova,  which  have  originated  from 
single  cells  of  the  germ  epithelium  (Figs.  88,  90).     It  is  important  to  note 


Fig.  88. — From  a  section 
through  the  cortex  of  the 
ovary  of  a  rabbit,  90  times 
magnified.  1,  primary  fol- 
licle ;  2,  follicle  lined  with 
a  layer  of  cylindrical  epi- 
thelial cells  ;  3,  follicle 
with  stratified  epithelium. 
K,  germ  epithelium  ;  T, 
tunica  albuginea  (slightly 
developed)  ;  Th,  theca  fol- 
liculi ;  Fe,  follicle  epithel- 
ium ;  Zp,  zona  pellucida. 
D,  yolk  ;  Kf,  germinal 
vesicle  with  punctiform 
germ  spots.  (Method  No. 
8,  Appendix.) 


Fig.  89. — Diagrammatic  section 
through  the  posterior  end  of  a 
young  warm-blooded  embryo, 
the  spinal  cord  not  shown. 
A,  Aorta  ;  V,  veins  ;  Al,  canal 
of  allantois  ;  D,  intestinal  canal. 
Round  this  is  the  peritoneal 
cavity,  and  at  K  the  germinal 
epithelium.  W,  Canal  of  the 
primitive  kidney. 


in  passing  that  this  germ  epithelium  is  the  same  as  gives  rise  in  the 
male  to  the  cells  that  have  to  do  with  the  production  of  spermatozoids 
(Fig.  89).  In  the  course  of  developinent,  groups  of  cylindrical  cells 
grow  up  from  the  stroma  of  the  ovary  so  as  to  enclose  the  primordial  ova. 
These  may  even  form  tubular-like  structures,  called  by  some  German 
writers  the  ova  tubes.     By-and-bye,  each  ovum  is  surrounded  by  cells, 


222  THE  PHYSIOLOGY  OF  THE  TISSUES. 

forming  a  little  round  body  called  the  primary  follicle,  -which  consists 
of  the  ovum  and  of  epithelial  cells  surrounding  it.  The  formation  of 
this  follicle  around  each  ovum   is   for  the  purpose,  in   due   time,   of 

ejecting  the  ovum  from  the  ovary. 
The  size  of  the  follicle  increases  by 
the  multiplication  of  epithelium 
cells,  and,  by-and-bye,  a  space  exists 
round  the  ovum  which  is  filled 
with  a  fluid,  the  liquor  foUimli. 
This  liquid  may  be  formed  by 
FiQ.  90. -Vertical  section  of  ovary  of  a  girl  four    transudation  from  the  surrouuding 

weeks   old,   240    times    niagmfiea.      K,    germ  ~ 

epithelium  ;    P,  primordial  ovum,  with    large  blood-veSSels,    and,    aS     SOme     haVC 

nucleus    and  nucleolus  ;      E,   group   of    three  '             ' 

ova  surrounded  by  cylindrical  cells;  P/,  primary  gUgSiested,     bv     the     disinteSiration 

follicle ;    F,   epithelium   of    follicle ;    D,   yolk  ■  i=>a             J        J                                  a 

Kb,    germinal    vesicle ;      Kf,    germinal    spot,  and    meltinS!   awav  of   SOme    of  the 

(Method  No.  9,  Appendix.)  '^             -^ 

epithelial  ceils.  We  have  now  a 
vesicle  filled  with  fluid,  the  Graafian  vesicle,  having  a  diameter  of  from 
•5  to  5  mm.  The  connective  tissue  forms  the  wall  of  the  vesicle.  It 
•consists  of  (1)  a  connective  tissue  covering  the  theca  foUiadi,  Avhich  is 
formed  of  two  strata,  an  outer  (a)  of  fibrous  tissue,  tunica  fibrosa,  and 
ih)  an  inner  tunica  propria,  rich  in  cells  and  vessels  ;  (2)  a  lining  of 
stratified  follicular  epithelium,  sometimes  called  the  memhrana  granulosa. 
This  lining  of  epithelial  cells  forms  a  prominence  at  one  side,  called  the 
citmulus  ovigerus  or  discus  proligerus,  and  the  layer  surrounding  the  ovum 
has  been  termed  the  tunica  gramdosa.  The  space  is  occupied,  as  already 
mentioned,  by  the  liquor f  oil iculi.  A  mature  human  ovum  measures  in  dia- 
meter from  1-1 25th  to  1-1 50th  of  an  inch  =  180  /a.  The  germinal  vesicle 
is  about  l-500th  of  an  inch  in  diameter  =  50  [x.  It  is  important  to  note  in 
this  connection  that  the  head  of  the  spermatozoid  is  the  1-6 250th  of  an 
inch  in  length,  and  about  l-8000th  of  an  inch  broad,  so  that  the  size 
of  the  male  nuclear  element  is  only  about  1-1 2th  part  of  that  of  the 
female  nuclear  element  (Fig.  91). 

When  the  ovum  reaches  maturity,  the  Graafian  vesicle  is  full  of  fluid, 
and,  as  already  mentioned,  bulges  out  from  the  surface  of  the  ovary. 
The  vessels  in  the  neighbourhood  of  the  vesicle  become  much  congested, 
and  at  a  given  time  the  vesicle  bursts  and  extrudes  its  contents.  This 
is  assisted  by  a  rupture  of  some  of  the  finer  vessels,  causing  a  haemor- 
rhage into  the  cavity  of  the  vesicle.  Coincident  with  these  changes,  by 
a  reflex  mechanism,  the  exciting  cause  of  which  is  not  known,  the  end 
of  the  Fallopian  tube  is  applied  to  the  ovary,  and  the  oviun  escapes 
into  it  and  passes  to  the  uterus.  During  its  passage  down  the 
Fallopian  tube  it  meets  with  the  spermatozoids,  and  then  fecunda- 
tion occurs. 


TEE  ORIGIN  OF  TEE  TISSUES. 


223 


Fig.  91. — Section  of  the  Graafian  follicle  of  a  girl  eight  years  old,  90  times 
magnified.  Th,  theca  foUiculi  ;  Tf,  tunica  fibrosa  ;  Tp,  tunica  propria  ; 
M,  membrana  granulosa — follicular  epithelium  ;  C,  discus  or  cumulus 
ovigerus  ;  E,  ovum,  with  zona  pellucida,  germinal  vesicle,  and  germinal 
spot.  The  clear  space  in  the  middle  contains  the  liquor  folliculi. 
(Method  No.  10,  Appendix.) 


3.  Influence  of  Spermatozoid  on  Ovum. — The  question  now  arises, 
what  is  the  influence  of  the  spermatozoid  upon  the  ovum  ?  It 
is  interesting  for  a  moment  to  notice  the  historical  development  of 
knowledge  upon  this  question.  The  first  step  in  this  direction  was 
made  by  Kolreuter  in  1761,  when  he  succeeded  in  artificially  pro- 
ducing hybrids  by  the  cross  fertilization  of  plants.  Soon  after  this 
Jacobi  artificially  fertilized  the  eggs  of  the  trout  and  salmon,  and  in 
1780,  Spallanzani  operated  in  the  same  way  on  the  frog,  the  tortoise, 
and  the  dog.  Curiously,  however,  he  thought  that  the  virtue  lay 
in  the  fluid  and  not  in  the  living  particles.  In  1824,  Prevost  and 
Dumas  proved  that  the  seminal  fluid  lost  its  effect  after  filtration 
Martin  Barry  observed  spermatozoids  in  the  ovum  of  the  rabbit  in 
1843  ;  Leuckart  made  the  same  observation  in  the  frog  in  1849  ;  Nelson, 
in  1852,  observed  the  spermatozoids  in  the  egg  of  A  scans  mystax ;  and 
in  1853,  Keber  observed  the  actual  entrance  of  the  spermatozoon  into 
the  egg  of  the  common  mussel.  The  subject  also  attracted  the  attention 
of  Bischoflf,  whose  researches  into  the  development  of  the  dog  were  of 


224  THE  PHYSIOLOGY  OF  THE  TISSUES. 

great  value,  and  of  the  late  Dx\  Allen  Thomson.  It  was  supposed  that 
the  spennatozoids  entered  the  ovum,  disappeared,  and  in  some  mysteri- 
ous way  set  up  changes  which  resulted  in  the  cleavage  of  the  yolk,  or  more 
strictly  speaking,  in  the  formation  of  the  first  two  cells  of  the  embyro 
— the  first  two  blastomeres.  Opinion  remained  in  this  vague  condition 
until  1872,  when  Biitschli  made  the  remarkable  observation  of  hvo 
nuclei  in  the  fecundated  egg  of  Bhahditis  doUclmra,  a  nematode  worm. 
As  often  happens  in  science,  Auerbach,  in  1874,  made  a  similar  observa- 
tion on  the  eggs  of  two  other  worms — Ascaris  nigrovenosa  and  Strongylus 
auricularis — without  kno'\\ang  of  Biitschli's  description.  Biitschli 
followed  up  his  work  in  1875,  by  discovering  the  same  phenomenon  in 
the  eggs  of  the  gastropods — Lymncea  sfagnalis  and  Succinea  Pfeifferi. 
He  also  noticed  in  the  eggs  of  these  molluscs  a  peculiar  fibrillated 
appearance,  such  as  occurs  in  connection  vnth  the  division  of  nuclei. 
These  investigations  Avere  quickly  followed  by  those  of  0.  Hert"vvig, 
Ed.  van  Beneden,  and  Fol.  It  is  to  be  observed  that  Biitschli  did  not 
explain  the  origin  of  the  second  nucleus  which  he  had  observed  in  the 
fecundated  egg.  This  was  accomplished  by  0.  Hert-\\ag,  when,  in  1875, 
he  published  his  researches  on  the  development  of  Toxojmeusfes  lividus, 
an  echinoderm.  He  has  the  merit  of  demonstrating  that  the  second 
nucleus  is  the  head  of  the  spermatozoon.  Further,  0.  HertAvig  at 
first  supposed  that  the  other  nucleus  was  the  germinal  spot  of  Wagner 
set  free  by  the  destruction  of  the  germinal  vesicle.  This  error  was 
pointed  out  by  Van  Beneden,  and  0.  Hertwig  accepted  the  correction, 
with  the  resiilt  that  the  other  nucleus  was  soon  shown  to  be,  as  Biitschli 
had  previously  conjectured,  the  germinal  vesicle.  The  distinguished 
Belgian  naturalist,  E.  van  Beneden,  early  recognized  the  importance  of 
these  observations.  In  1875,  he  described  the  fusion  of  the  nuclei,  and 
expressed  the  opinion  that  in  the  fusion  of  the  two  nuclei  there  was  a 
phenomenon  comparable  to  the  conjugation  of  the  Protozoa  and  Proto- 
phyta ;  and  in  his  magnificent  monograph  on  the  fecundation  of  Ascaris 
megalocephala  (1883)  he  has  largely  advanced  our  knowledge  of  the 
subject.  Although  the  entrance  of  the  spermatozoon  had  been  pre- 
viously observed,  no  specific  changes  were  immediately  noticed.  This 
was  reserved  for  Fol,  a  Swiss  naturalist,  who,  in  1877,  observed  the 
entrance  of  the  spermatozoid  into  the  eggs  of  Asterias  glacialis  (a  star- 
fish), and  of  various  species  oi  Echinus  (sea-urchins);  and  he  studied  and 
figured  the  phenomena  that  ensued.  These  observations  have  been 
confirmed  by  many  naturalists  (Fig.  92). 


THE  ORIGIN  OF  THE  TISSUES. 


99.- 


^      -kikfi 


v-a 


Fig.  92. —Fecundation  of  the  eggs  of  Astenas  glacialis.  s-p,  Sper- 
matozoids.  The  spermatozoid's  are  in  the  mucus  covering  the 
egg.  At  ^,  a  spermatozoid  has  reached  the  periphery  of  the 
yolk.  At  B,  several  are  moving  onwards  towards  a  prominence 
in  the  surface  of  the  yolk.  At  C,  the  heads  of  one  or  two  sper- 
matozoids  have  united  with  and  penetrated  into  this  prominence. 


4.  The  Formation  and  Expression  of  Polar  Bodies. — Another  series 
of  phenomena  has  been  brought  to  light.  It  is  well  known  from 
the  researches  of  Strasburger  and  others  that,  in  the  development 
of  the  reproductive  organs  of  plants,  certain  portions  of  the  matter 
that  is  devoted  to  the  formation  of  spores,  antherozoids,  and  oospheres 
(or  ova)  are  not  used  for  that  purpose,  but  are  extruded  or  othermse 
laid  aside  from  taking  part  in  the  reproductive  process.  Thus, 
in  the  sporangium  of  many  fungi,  a  part  of  the  protoplasm,  called 
the  epiplasm,  remains  over  after  the  formation  of  the  spores.  In  the 
development  of  the  zoospores  of  algse  a  part  of  the  protoplasm,  not 
used  up,  is  extruded  in  the  form  of  a  vesicle  from  the  sporangium,  and 
Strasburger  states  that  in  some  cases,  just  before  the  division  of  the 
spore-mother-cell,  a  mass  of  stuff  is  extruded  from  the  nucleus,  called 
the  paranudeoliis.  Similar  phenomena  have  been  observed  in  sexually- 
reproductive  cells.  The  male  element  of  mosses,  the  antherozoid,  has 
an  appendage  attached  to  its  posterior  end.  This  appendage  or  vesicle 
has  been  found  to  be  the  "  unused  protoplasm  of  the  mother-cell,"  along 
Avith  actually  a  portion  of  the  nucleus,  which  is  thus  excluded.  In  the 
angiosperms,  during  the  development  of  the  nucleus  and  the  protoplasm 
of  the  pollen  grain  (the  male  portion)  cell-like  bodies  are  formed  which 
are  separated  from  the  generative  cell.  Similar  phenomena  are  noticed 
in  the  development  of  the  female  structures  or  gametes,  that  is  to  say, 
portions  of  protoplasm  are  extruded  from  the  oogonium.  Even  in 
angiosperms  nuclear  divisions  take  place  in  connection  with  the 
I.  P 


220  THE  PJ/rSIOLOGY  OF  THE  TISSUES. 

(leveloimicnt   of  the   oosphere   or   ovum.     Thus,    to   quote   from  Dr. 
Sydney  Howard  Tines— 

"  The  nucleus  of  the  young  embryo-sac  divides  into  two,  one  of  which  travels  to 
each  end  of  the  sac  ;  each  nucleus  then  divides,  and  each  of  the  two  nuclei  divides 
again,  so  that  there  is  a  group  of  four  nuclei  at  each  end  of  the  embryo-sac.  Of 
those  at  the  micropylar  end,  one  becomes  the  nucleus  of  the  oosphere,  two  the 
nuclei  of  the  synergid^,  and  the  fourth  (polar  nucleus),  which  is  the  sister  nucleus 
of  that  of  the  oosphere,  travels  towards  the  middle  of  the  sac,  where  it  fuses  with 
one  of  the  chalazal  nuclei,  which  has  likewise  travelled  towards  the  middle  of  the 
sac,  to  form  the  definitive  nucleus  of  the  embryo-sac.  It  may  be  suggested  that 
the  division  which  leads  to  the  formation  of  the  nucleus  of  the  oosphere,  and  of 
the  so-called  polar  nucleus,  is  the  one  which  we  are  seeking ;  in  that  case  the 
so-called  polar  nucleus  would  be  the  polar  body." 

It  appears,  therefore,  that  in  the  development  both  of  non-sexual 
spores  and  of  male  and  female  elements  in  plants  a  portion  of  the 
original  nuclear  substance  is  extruded  or  thrown  aside  and  takes  no 
share  in  the  reproductive  process.  The  portions  thus  laid  aside  or 
extruded  have  been  called  polar  bodies.  It  is  remarkable  that  analogous 
phenomena  occur  in  the  development  of  the  ova  and  of  the  sperm  cells 
of  animals. 

The  extrusion  of  minute  particles  of  matter,  or  polar  bodies,  from  the 
e*'"  Avas  first  observed  by  Dumortier  in  the  egg  of  Lymncea  stagnalis  in 
1837,  and  the  phenomenon  was  investigated  by  F.  Miiller  in  1848.  No 
relation  between  these  bodies  and  the  germinal  vesicle  was  noticed  until 
the  researches  of  Biitschli  in  1875,  to  which  I  have  previously  referred. 
He  observed  a  curious  spindle-shaped  structure  passing  between  the 
terminal  vesicle  and  the  surface  of  the  o\aim.  In  1876,  Ed.  van 
Beneden  detected  the  extrusion  of  two  polar  bodies  from  the  egg  of 
Asteracanthion  rubens.  The  researches  of  Fol,  Selenka,  and  0.  Hertwig 
not  only  corroborated  these  observations,  but  manj-  details  of  the  pheno- 
mena connected  with  their  formation  and  extrusion  were  observed. 
Thus  Calberla  noticed  that  changes  occurred  in  the  germinal  vesicle 
along  wath  the  extrusion  of  the  polar  bodies,  and  that  these  bodies 
might  be  eliminated  even  before  the  egg  reached  its  maturity.  In  the 
great  majority  of  cases  the  formation  of  the  polar  bodies  preceded  the 
union  of  the  sexual  elements,  and  researches  by  Fol  and  others  have 
shown  that  the  genesis  of  these  bodies  is  independent  of  fecundation. 

Let  us  now  examine  what  actually  occurs.  When  the  o^nim  is  ripe  it 
consists,  as  already  described,  of  a  cell  wall  enclosing  contents,  in  which 
is  embedded  the  nucleus  or  germinal  vesicle,  in  which  again  is  the 
nucleolus  or  germinal  spot.  Previous,  then,  to  actual  fecundation 
(although  the  spermatozoid  maj'  have  penetrated  the  o^aim),  a  fusiform 


THE  ORIGIN'  OF  THE  TISSUES. 


227 


■ioxvM-^^^^-i- 


ya 


iDody  is  seen  (the  "  direction-spindle  "  of  Biitsclili,  and  the  "  amphiastcr 
■of  rejection"  of  Fol),  as  was  first  de- 
scribed by  Biitschli,  stretching  from  the 
germinal  vesicle  (Fig.  93)  towards   the 

surface  of  the  ovum,  so  that  one  end  of   ,,^...^. .„..„.„,,,  „,,„..,,.,,. ^^.-q.^.  ._., 

the  spindle  touches  the  surface  whilst     '°^°i^§i0MM'J6'^§^°^&§i^^o^' 
the  other  is  in  contact  with  the  germinal 
vesicle.     At  the  same   time,  or   rather 
immediately   before   the   appearance  of 

the  spindle,  the  wall  of  the  germinal  around  the  polar  body ;  c,yoik, 
vesicle  becomes  less  and  less  distinct,  and  the  protoplasm  in  its  immediate 
■vicinity  assumes  a  radiated  appearance.  There  is  every  reason  to 
believe  that  a  portion  of  the  substance  of  the  germinal  vesicle  forms  part 
of  the  spindle.  By-and-bye  a  small  globule  protruding  from  the  surface 
of  the  ovum  ajjpears  at  the  external  end  of  the  spindle.  This  is  the  first 
polar  body.  In  most  cases  a  second  spindle  is  formed,  and  there  is  the 
extrusion  of  a  second  polar  body.  Biitschli  thought  that  the  spindle 
was  entirely  extruded  in  the  polar  body,  but  Fol  and  Hertwig  have 


Fig.  93.— Extrusion  of  ii  polar  body  from 
the  egg  of  a  snail,  Succineo,  Pj'eifferi.  a, 
polar  body  showing  elongated  filaments 
of  nuclear  matter ;  6,  radiated  appearance 


Fig.  94. — A,  ripe  ovum  of  Astenas  glacialis  with  excentric  germinal  vesicle 
and  spot.  £,  C,  D,  E,  gradual  metamorphosis  of  germinal  vesicle  and  spot ; 
F,  detachment  of  first  polar  body  and  withdrawal  of  remaining  part  of 
nuclear  spindle  within  the  ovum  ;  G,  portion  of  living  ovum  with  first 
polar  body  ;  H,  formation  of  second  polar  body  ;  I,  after  formation  of  the 
same,  showinj;;  the  remaining  internal  half  of  the  spindle  in  the  foi-m  of 
two  clear  vesicles  ;  K,  ovum  with  two  polar  bodies  and  radial  strise  around 
female  pronucleus  ;  L,  expulsion  of  polar  body  {A — K,  after  Fol ;  L,  after 
Hertwig). 

shown  that  this  is  not  the  case.  As  to  the  genesis  of  the  spindle  itself 
there  is  still  considerable  difference  of  opinion.  Biitschli  conceived  that 
the  fibres  of  the  spindle  were  formed  by  the  coalescence  of  granules. 
Fol  described  them  as  due  to  a  swollen  condition  of  the  "  filaments  bi- 
polair,"  meaning  certain  filaments  passing  from  the  germinal  vesicle 
towards  each  pole  of  the  egg.  0.  Hertwig  supposes  that  they  arise  from 
the  fragments  of  the  wall  of  the  germinal  vesicle  and  of  the  germinal 
spot ;  and  these  views  of  Hertwig  have  been  supported  by  Trinchese 
:and  Blochmann. 

Considerable  discussion  has  taken  place  as  to  whether  these  pheno- 


228 


rilE  PHYSIOLOGY  OF  THE  TISSUES. 


menu  belong  to  the  class  of  changes  occurring  in  kary olcinesis.  Flemming, 
in  1882,  after  a  careful  study  of  the  egg  by  the  methods  followed  in  the- 
observation  of  karyokinesis,  came  to  the  opinion  that  the  phenomena  arc 
the  same,  with  this  difference,  that  in  the  egg  the  chromatin  element 
does  not  l>ulk  so  largely  as  the  achromatin  constituent,  the  result  being 
that  in  the  karyoldnesis  of  cells  the  chromatin  figures  are  the  more 
apparent,  Avhereas  in  the  egg  the  achromatin  figures  arrest  the  attention. 
This  A-iew  is  well  illustrated  by  the  figures  of  ordinary  karyokinesis 
■-■iven  by  Rabl  (Fig.  95),  in  which  the  achromatin  spindle-like  figures  are 


Mm 


n. 


L 


D. 


Fio.  !I5. — DiaffTiini  showing  the  mode  of  uucloar  division.  A  shows  strongly  marked  chromutiiT 
filaments  with  the  spindle  figure.  At  the  ends  or  points  of  the  spindle  observe  the  star-.shaped  or 
radiating  arrangement  of  the  protoplasm,  and  in  the  middle  of  the  spindle  the  chromatin  filaments. 
In  the  latter  a  longitu<linal  division  of  the  filaments  has  already  begim.  B  shows  the  number  of 
chromatin  filaments  multiplied  by  division  and  beginning  to  be  arranged  with  the  loops  in  the 
same  direction  as  the  spindle.  V  shows  the  loops  still  more  regularly  arranged.  D.  both  groups 
of  the  filaments  or  loops  have  retreated  towards  the  poles  of  the  spindle. 

^•ery  distinctly  sho'sni ;  on  the  other  hand,  as  E.  van  Beneden  points  out,. 
Hofmann  is  the  only  observer  who  has  described  the  spindle  in  the 
mammalian  egg,  whilst  he  himself  has  looked  for  it  in  vain,  and  he 

inclines  to  the  view  that  the  extrusion 
of  the  polar  body  is  not  an  example  of 
ordinary  karyokinesis,  in  which  the 
ovum  may  be  regarded  as  simply 
dividing,  so  that  one  half  is  the  minute 
polar  body,  Avhilst  the  other  half  is  the 
rest  of  the  o^iim,  but  that  it  is  really  a 
physiological  j)rocess  peculiar  to  the 
ovum.  In  the  development  of  the  egg^ 
of  Ascaris  megcdocejyhala,  E.  A'an  Beneden 
describes  a  peculiar  figure  termed  by 
him  the  ypsiliform  figure  from  its 
resemblance  to  the  Greek  letter  Y 
(Fig.  96).  It  may  be  compared  to  the 
toy  known  as  the  "cup  and  ball,"  the 
stalk  of  the  cup  being  the  vertical  portion  of  the  Y,  and  supposed  by 
Van  Beneden  to  be  like  a  thread  or  cord,  whilst  the  two  diverging 


Fig.  9t). — Egg  of  Ascaris  megcdocephnla 
showing  the  Y-shaped  figure,  having  deli- 
cate protoplasmic  filaments  connected 
with  it  The  altered  spermatozoid  is  seen 
in  the  lower  left  hand  portion  of  the  egg. 


THE  ORIGIN  OF  THE  TISSUES. 


229 


limbs  are  really  sections  of  tlie  sides  of  the  cup.  In  the  hollow  of  the 
cup  there  is  a  mass  of  clear  homogeneous  matter,  containing  chromatin 
globules,  corresponding  to  the  ball  in  the  well-known  toy.  The  fibrils 
of  the  Y-shaped  body  originate  in  fine  granules,  which  are  the  remains 
of  the  membrane  of  the  germinal  vesicle,  along  Avith  some  of  the  sur- 
rounding protoi:)lasm.  At  the  end  of  each  limb  of  the  Y  there  is  also  a 
little  mass  of  granules,  and  around  the  stem  of  the  Y,  and  running  up  so 
a,s  to  assist  in  forming  the  cup,  there  is  a  clear  transparent  mass  to 
which  he  gives  the  name  oi  ])rothyalosome.  The  axial  fibres,  those  form- 
ing the  stem  of  the  Y,  appear  first.  Thus,  in  the  first  instance,  a 
fusiform  figure  appears,  the  pointed  ends  corresponding  to  the  ends 
of  the  stem  of  the  Y.  ISText  two  other  centres  of  attraction 
appear  in  the  prothyalosome,  like  two  stars  or  radiant  points, 
the  fibrils  from  each  of  which  coalesce  at  the  upper  end  of  the 
stem  of  the  Y,  thus  giving  rise  to  the 
Y-shaped  figure.  At  first  the  Y-shaped 
figure  is  near  the  centre  of  the  ovum, 
but  it  gradually  approaches  the  peri- 
phery, and  the  point  of  each  limb  of 
the  Y  touches  the  vitelline  surface, 
although  not  at  the  same  time  (Figs. 
«7,  98,  and  99).  The  form  of  the  Y  then 
■changes  in  consequence  of  fibres  in  the 
two  limbs  uniting  transversely,  so  that 
it  becomes  more  homogeneous  in  ap- 
pearance ;  but  at  each  point  correspond- 
ing to  the  free  end  of  the  limb  of  the 
Y  there  is  a  little  star-shaped  cluster 
of  chromatin  granules.  As  the  Y- 
shaped  body  approaches  the  surface, 
the  stem  of  the  Y  lengthens,  and  the 
fibres  become  less  and  less  distinct,  and 
at  the  lower  end  the  matter  forming 
the  head  of  the  spermatozoid  is  ap- 
parent. The  first  polar  body  is  formed 
of  a  portion  of  the  chromatin  stars  at 
the  ends  of  the  limbs  of  the  Y,  along 
with  a  portion  of  the  clear  matter  sur- 
rounding the  limbs  and  forming  the  cup — the  prothyalosome ;  and 
E.  van  Beneden  attaches  great  importance  to  the  fact  that  division  does 
not  occur  so  as  to  cut  the  pole  (that  is  to  say,  the  limb  of  the  Y,  ynth 
rsurrounding  matter)  transversely,  but  the  division  takes  place  equa- 


FiG.  97— Shows  Y-shaped  figure  near 
the  surface,  with  the  upper  lirobs  of 
the  Y  flattened  out  so  as  to  make  the 
figure  T-shaped.  Observe  also  the 
transverse  strise.  Egg  of  Ascaris 
■iueualoce2:>hala. 


Fig.  9S. — The  upper  part  of  the  Y- 
shaped  figure  has  now  reached  the 
surface  of  the  et^g,  or  stage  prior  to 
the  genesis  of  the  first  polar  body, 
which  is  formed  by  transverse  cleav- 
age.    Egg  of  Ascaris  tnecjcdoce-phola. 


Fig.  09. — Formation  of  the  first  polar 
body  in  egg  of  Ascaris  mepalocephala, 
indicating  one  of  the  last  modifica- 
tions of  the  Y-shaped  body. 


230 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


tonally,  just  as  if  the  limbs  of  the  Y  had  opened  out,  and  each  limb 
had  lieen  cut  in  the  direction  of  its  length.  In  all  cases  of  ordinary 
karyokinesis  the  cleavage  always  takes  place  transversely  to  the  direction 
of  the  filaments  of  the  spindle,  and  if  Ave  recognize  the  Y-shaped  figure 
of  E.  A-an  Bejiedon  as  being  formed  of  two  spindles,  the  importance  of  his 
observ'ation  will  be  appreciated.  The  formation  of  the  polar  globules, 
cannot  therefore  be  deemed  an  example  of  karyokinesis  :  at  all  events^ 
it  is  not  of  the  usual  type.  After  the  removal  of  both  the  polar  bodies^ 
the  portions  of  the  chromatic  stars  or  discs,  along  A\dth  the  neighbour- 
ing portions  of  the  prothyalosome,  unite  to  form  a  body,  which  is  in 
all  respects  similar  to  the  polar  bodies  extruded.  This  he  terms  the- 
deuthjalosome. 

This  body,  the  deuthj-alosomc,  may  be  regarded,  then,  as  formed  of 
the  remains  of  the  germinal  vesicle.  The  vesicle,  b}'  this  elaborate 
process — Avhich  occurs  hefore  fecundation,  although  it  may  be  going  on 
while  the  spermatozoon  is  in  the  egg — has  throAvn  off  a  portion  of  itself, 
and  the  body  Avhich  remains  at  the  end  of  the  process  cannot  be- 
regarded,  morphologically  or  physiologically,  as  an  ordinary  cell 
nucleus. 


Xow  Ave  approach  true  fecundation.    It  has  l)een  ascertained  that  one 

single  spermatozoon  is  sufficient  for 
the  process.  Entering  the  ovum, 
either  by  a  distinct  aperture  (in  the 
OATim),  termed  the  micropijle  (Fig. 
100),  or,  AA'here  no  special  aperture 
has  been  observed,  through  the  cell 
Avail,  it  quicldy  undergoes  chemical 
and  physical  changes.  It  becomes 
more  susceptible  to  the  action  of 
colouring  matters,  and  instead  of 
being  granular  it  assumes  a  homo- 
geneous apiDearance.  The  tail  dis- 
appears, and  the  head  becomes 
globular  in  form.  E.  A^an  Beneden 
has  obserA^ed  in  many  eggs  a  re- 
fringent  globule,  similar  in  appear- 
ance to  a  body  seen  in  the 
spermatozoid,  and  he  has  no  doubt 
that  this  body  has  been  throA\Ti  off 
by  the  spermatozoid,  and  finally  ejected  from  the  egg  itself,  probably 
Avith  the  second  polar  body.     This  importo-nt  obserA^ation  is  of  profound 


Fig.  100. — A,  blind  end  or  cid-de-sac  of  the 
ovary  of  a  star  fish.  B  and  C,  development 
of  the  egg  of  Holulhuria  Bohadschia,  after 
Semper.  B,  young  egg  with  the  surround- 
ing epithelial  cells  detached ;  at  'lU,  the 
opening  of  the  micropyle.  0,  ripe  egg, 
showing  a  thickened  zona  pellucida,  and 
the  epithelial  cells  much  elongated ;  m, 
micropyle,  very  narrow.  D,  egg  of  Unio, 
showing  micropyle  at  in. 


THE  ORIGIN  OF  THE  TISSUES. 


231 


significance,  as  showing  that  the  spermatozoid  (as  well  as  the  germinal 
vesicle)  gets  rid  of  a  part  of  its  substance  {seminal  granule)  before 
fecundation  occurs.^ 

The  body  left  in  the  egg  after  the  formation  of  the  two  polar  bodies 
is  termed  the  female  jpronucleus,  while  that  formed  by  the  head  of  the 
spermatozoid  is  the  male  pronucleus.  Until  the  second  polar  body  has 
been  extruded,  the  spermatozoid  remains  inactive,  but  when  this  has 
occurred  a  series  of  changes  ensues,  which  ends  in  the  division  of  the 
first  cell  of  the  embryo  into  two  cells  (Figs.  101  and  102). 


Fig.  101. — Eipe  egg  of  a  sea  urchin 
(Echinus),  en.,  egg  nucleus,  or  ger- 
minal vesicle. 


Fig.  102.  —Fecundated  egg  of  a  sea  urchin. 
The  head  of  the  spermatozoid,  consti- 
tuting the  spermatozoid  nucleus,  sp.  n. 
or  male  pronucleus,  is  surrounded  by 
radiated  protoplasm ;  en.,  egg  nucleus, 
or  female  pronucleus. 


Fro.  103. — Fecundated  egg  of  a  sea 
ixrchin,  sp.  n.  Spermatozoid  nucleus, 
or  Eiale  pronucleus;  en.,  egg  nucleus, 
or  female  pronucleus.  The  two  pro- 
nuclei are  close  together,  and  are 
both  surrounded  by  a  radiated  mass 
of  protoplasm . 


Fia.  104. — Eg<;-  of  a  sea  urchin  immediately 
after  fecundation.  rn.,  fecundation 
nucleus.  Both  the  male  and  female  pro- 
nuclei have  disappeared,  and  ai-ound  the 
fecimdation  nucleus  the  protoplasm  has 
a  radiated  appearance. 


^  Further,  E.  van  Beneden  and  Ch.  Julin  have  discovered  the  expulsion  by  the 
spermatomere  of  a  minute  globule,  which  does  not  therefore  enter  into  the  formation 
of  the  spermatozoid.  La  spermatogenese  ches  I'ascaride  megalocephale.  Bull,  de 
VAcadimie  Royale  de  Belgique,  1S84.  The  separation  of  a  globule  has  also  been 
described  by  J.  E.  Blomfield  on  The  Development  of  the  Spermatozoa,  part  1, 
Lumbricus  (Earth  worm),  Quart.  Jour,  of  Micros.  Science,  1880.      See  also  on 


•232  THE  PHYSIOLOGY  OF  THE  TISSUES. 

The  female  pronucleus  is  now  a  nucleus  containing  two  chromatin 
filaments,  or  loops,  originally  derived  from  the  germinal  vesicle  of  the 
egg.  It  is  very  curious  to  find  that  the  number  of  loops  seen  in  the 
various  stages  of  these  processes  is  very  constant.  Thiis,  in  the  ger- 
minal vesicle  there  are  two  chromatin  plates,  each  composed  of  four 
chromatin  globules  ;  the  same  in  the  Y-shaped  figure  ;  in  the  first  polai- 
bod)'  two  chromatin  bodies,  each  formed  of  two  smaller  ones ;  in  the 
deuthyalosome,  two  chromatin  filaments,  each  dividing  into  two ;  the 
same  in  the  second  polar  body ;  and  now  in  the  female  pronucleus  again 
two  chromatin  loops,  each  formed  of  two  smaller  portions. 

The  male  pronucleus  is  formed  from  the  head  of  the  spcrmatozoid, 
and  it  also  contains  two  portions  of  chromatin.  It  is  found  near  the 
lower  pole  of  the  egg. 

The  two  pronuclei  approach  each  other,  and  ultimately  unite. 
According  to  0.  Hertwig,  Fol,  and  Mark,  there  is  a  complete  fusion. 
This  is  fecundation,  the  union  at  last  of  the  two  elements  (Figs.  103 
and  104). 

E.  van  Beneden,  in  the  Ascaris  megalocephala  has  not  observed  com- 
plete fusion;  on  the  contrary,  he  has  been  able  to  observe  in  the 
karyokinetic  process  which  immediately  follows,  that  the  chromatin 
filaments  supplied  by  the  male  and  female  elements  remain  distinct,  so 
that  in  the  two  cells  formed  by  the  division  of  the  first  cell  each  new 
nucleus  receives  an  ecpial  portion  of  male  and  female  elements.  He 
divides  the  process  into  four  stages.     1st.  The  four  chromatin  filaments 

increase  in  size  and  become  coiled  to 
a  greater  or  less  extent.  It  is  to  be 
remembered  that  two  have  been 
supplied  by  the  male  and  two  by 
the   female   pronucleus.       2nd.    The 

Fig.  105.— Arrangement  of  chromatin  fila-  COntOUrS     of     the     pronuclei     becOme 
nients  in  the  equator  of  the  egg  of  .-isan-is  ,  ,  ,.      . 

mef/atncepkala.    The  filaments  form  the  leSS  and  IcSS  dlStmct;    each  chromatin 
dark  irregularly-shaped  bar.      Only  the  t    •  t  i  ■  i 

middle  portion  of  the  egg  is  shown.  loop      dlVldeS      traUSVersely      lU      the 

middle  so  that  there  are  now  eight 
loops,  and  the  eight  loops  of  chromatin  move  so  that  the  shut  end  of 
each  loop  is  directed  towards  the  equator  of  the  fecundation  nucleus. 
Imagine  an  orange  wdth  eight  loops  of  cord  placed  equatorially  in  it, 
the  ends  directed  toAvards  the  axis  passing  from  pole  to  pole.  3rd. 
Each  loop  is  then  divided  longitudinally,  thus  giving  rise  to  sixteen 
loops,  and  the  two  groups  of  eight  are  separated  by  a  thin  layer  of 

this  question  Herbert  H.  Brown's  paper  on  Spermatogenesis  in  the  rat,  Quart. 
Jour,  of  Micros.  Science,  1885,  in  which  Prof.  Eay  Lankester"s  opinion  is  given 
as  regards  the  globule  in  case  of  Earth  worm,  p.  20. 


THE  ORIGIN  OF  THE  TISSUES. 


233 


matter.  4th.  Each  of  these  groups  of  eight  is  now  situated  in  what 
E.  van  Beneden  terms  sub-equatorial  planes,  parallel  of  course  with  the 
equator  (Figs.  105,  106,  and  107). 


Fig.  106. — Stage  in  the  division  of 
the  egg  of  Escorts  nugalocephala, 
showing  the  chromatin  loops  sepa- 
i-ating  into  two  sets  and  retreating 
from  each  other. 


Pig.  107.— Stage  of  division  of  the 
egg  of  Ascaris  inerjcUocephcUa, 
showing  the  breaking  up  of  the 
chromatin  threaJs  into  minute 
globules,  and  in  some  places  a 
reticulated  appearance  from  the 
crossing  of  short  filaments. 


Thus  it  is  evident  that  each  loop  has  given  a  half  of  its  substance  to 
•each  of  the  daughter  nuclei,  and  as  there  was  an  equal  number  of  loops 
from  the  male  and  female  portions  to  start  "vvith,  it  follows  that  each 
daughter  nucleus  must  have  male  and  female  elements.  The  two  sets 
of  loops  recede  towards  the  poles  of  the 
nucleus,  and  then  there  is  division  of  the 
body  of  the  yolk,  according  to  the  ordinary 
method  of  karyokinesis  already  described. 
Further,  the  two  cells  thus  formed,  nourished 
by  the  fluids  in  which  they  exist,  increase  in 
size,  and  again  divide  karyoldnetically  into 
four.  The  process  is  repeated  over  and  over 
again  so  as  to  form  the  primitive  cells  from 
which  all  the  tissues  and  organs  of  the  body 
are  derived ;  and  if  the  karyokinetic  division 
is  repeated  so  that  portions  of  the  chromatin 
derived  from  the  male  and  female  elements  (multiplied  and  increased  in 
quantity  by  nutrition,  but  the  same  in  kind)  are  divided  equally,  it 
follows  that  all  cells  contain  equal  quantities  of  matter  related  to 
the   male   and   to   the   female  parent ;    and,   to    crown  all,  according 


Fig.  ids.— Egg  of  a  sea  urchin 
preparatory  to  cleavage. 


234 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


to    this   view,   each   living    cell   is    a    herma^jhrodite    being  ^    (Figs. 
108,  109,  110,  and  111). 


Fig.  100. — Egg  of  sea  urchin  at 
moment  of  division,  showing 
constriction  of  the  protoplasm 
at  ri;,'ht  angles  to  the  axis  of 
the  nucleus. 


Flo.llO. — Eju'-gof  sea  urchin  after 
division.  Observe  the  nucleus 
in  each  half.  The  streaked  ap- 
pearance of  the  ijrotoplasm 
begins  to  be  less  distinct. 


Fio.  111. — Various  stages  of  the  cleavage  of  the  egg  to  form  embryonal  cells. 


CH.iP.  III.— THEORIES  AS  TO  THE  PHYSIOLOGICAL  BASIS 
OF  HEREDITY. 

In  the  previous  chapter,  we  have  discussed  the  origin  of  the  cells  and 
of  the  living  matter  that  form  our  bodies.  One  is  naturally  inclined 
to  ask,  does  a  knowledge  of  these  phenomena  throw  any  light  upon 
the  Avell-known  facts  of  hereditary  transmission  ?  ^  Not  a  few  theories 
of  heredity  have  been  advanced.  The  oldest  of  all  is  that  the  soul  of 
an  ancestor  entered  the  body  of  a  newly  born  being  and  made  the  body 
like  that  in  which  it  had  at  one  time  existed.  The  theory  of  the  trans- 
migration of  souls  may  be  traced  to  very  remote  times,  and  it  exists 

^  This  view  is  associated  with  the  name  of  Professor  Sedgewick  Minot  of  Har- 
vard. Science,  vol.  iv.  18S4.  Also  Proceed.  Boston  Society  of  Natural  History, 
1877. 

-  Ch.  van  Bambeke,  "Pourquoi  nous  ressemblons  a  nos  parents."  Bull,  de 
VAcatUmie  Roycde  de  Belgiqm.  3™''-  serie,  torn.  x.  1885.  This  is  an  admirable 
resume  of  recent  speculations. 


PHYSIOLOGICAL  BASIS  OF  HEREDITY.  235 

almost  unmodified  in  the  opinions  of  some  of  the  so-called  savage  races 
of  the  present  day,  races  probably  representing,  however,  not  the 
primitive  type  of  thought  and  practice,  but  opinions  modified  in  the 
course  of  ages,  like  those  of  the  higher  and  civilized  races.  Stahl,  in 
accordance  with  his  mystical,  views,  held  that  the  soul  formed  the  foetus 
and  shaped  it  according  to  the  paternal  or  maternal  type.  Then,  in 
our  own  day,  came  the  doctrine  of  Pangenesis  of  Charles  Darwin,^ 
which  assumed  the  existence  in  all  cells  of  small  corpuscles  which 
circulate  free  in  the  body.  These  gemmules  are  transmitted  by  the 
parents,  and  they  are  usually  developed  in  the  next  generation,  but  may 
lie  dormant  for  generations,  and  their  evolution  depends  on  their  union 
with  gemmules  of  a  kindred  nature,  supplied  from  another  organism. 
This  theory  is  capable  of  explaining  many  of  the  facts,  but  it  labours 
under  the  disadvantage  that  there  is  no  vestige  of  proof  of  the  existence 
of  such  gemmules. 

Haeckel  ^  has  endeavoiu"ecl  to  solve  the  problem  by  supposing  that 
what  is  transmitted  is  not  matter  but  a  certain  kind  of  molecular  move- 
ment which  the  tissues  acquire  by  constant  repetition,  and  retain  by  a 
kind  of  unconscious  memory.  Heredity,  according  to  this  view,  would 
depend  on  the  more  or  less  accurate  transmission  of  sj^ecial  kinds  of 
molecular  movement,  while  variability  would  be  caused  by  the  action  of 
external  agencies  changing  more  or  less  the  character  of  the  movement 
so  transmitted.  The  obvious  criticism  on  this  theory  is,  that  we  as  yet 
know  far  too  little  of  the  character  of  molecular  movements,  to  make 
our  knowledge  the  basis  of  any  such  theory. 

Naegeli  rejects  both  the  theory  of  Pangenesis  of  Darwin  and  the  theory 
of  Perigenesis  of  Haeckel,  because  the  one  calls  in  the  aid  of  hypotheti- 
cal germs  and  the  other  of  hypothetical  movements,  and  he  endeavours 
to  establish  a  theory  on  the  basis  of  fact.  Protoplasm,  according  to 
him,  consists  of  two  portions,  one,  fluid,  called  hygroplasm,  and  the  other 
solid  or  insoluble,  stereoplasm.  The  stereoplasm,  however,  is  partly 
nutritive,  but  the  other  portion  called  idioplasm  is  the  seat  of  all  active 
changes.  This  idioplasm  ramifies  through  the  body,  is  in  every  cell  and 
tissue ;  and  each  tissue  has  its  own  kind  of  idioplasm,  so  that  there  is  a 

^  Charles  Darwin,  on  the  Variation  of  Plants  and  Animals  under  Domestication, 
1867,  chaps,  xxxvii.  and  xxxviii.  See  also  in  this  relation,  Herbert  Spencer's 
Principles  of  Biolo(jy,  vol.  i.  chaps,  iv.  and  viii.  Also,  Sir  Richard  Owen's  work 
on  Parthenogenesis,  1849.  It  is  interesting  also  to  read  Professor  Owen's  criticism 
of  Pangenesis  in  his  Comparative  Anatomy  and  Physiology  of  Vertebrates,  vol.  iii. 
p.  813. 

^Haeckel,  Die  Perigenesis  der  Plastidtde  oder  die  Wellenzeugung  der  Lebena 
theilchen,  Berlin,  1876. 


-230  ^V//v'  PIIVSlOLUaY  OF  THE  TISSUES. 

vast  variety  of  i(lioi)lasmi=;,  differing,  however,  more  dynamically  than  in 
any  detail  of  structure.     Reproductive  cells  contain  idioplasm  that  has 
returned  from  the  condition  of  somatic  idioplasm  to  the  state  of  the  idio- 
plasm of  the  germ  from  which  the  organism  sprang.     Further,  he  sup- 
poses that  the  specific  properties  of  the  idioplasm  depend  on  the  grouping 
of  more  minute  particles,  the  miceUa',  and  that  this  grouping  is  more 
complex  in  the  idioplasm  of  the  higher  beings  than  it  is  in  the  lower. 
Suppose,  then,  that  each  parent  transmits  an  equal  portion  of  idioplasm, 
there  -will  be  an  equal  transmission  of  the  peculiarities  of  each  parent ; 
and  if  one  idioplasm  predominates,  the  balance  may  lean  to  the  side  of 
the  fiither  or  of  the  mother.     This  mass  of  idioplasm,  as  already  said, 
extends  through  the  body,  having  subsidiary  characters  peculiar  to  each 
kind  of  cell,l:)ut  always  carryingwith  it  the  more  special  peculiarities  which 
it  had  at  first.     During  growth  it  retains  all  its  specific  characters,  and 
the  germ  cell  is  simply  a  cell  containing  idioplasm,  having  chieflj'  the 
primitive  character.     As,  however,  the  somatic  idioplasm  is  influenced 
by  external  conditions,  to  some  extent,  and  as  the  retiirn  of  the  somatic 
idioplasm  to  the  state  of  germinal  idioplasm  is  not  always  exact,  the 
offspring  never  exacth^  resemble  their  parents.     Hence  arises  variability. 
But   while  this   theory   is    founded   on  the   fact  that  there   is   an 
all-prevalent  matter — the  protoplasm, — it  is  liable  to  the  same  objection 
as  Avas  advanced  to  the  other  two  theories — it  is  too  conjectural.     The 
question  is,  where  is  this  idioplasm  1     If  it  is  the  reproductive  matter, 
it  must  exist  in  many  cells,  more  especially  in  those  which  yield  the 
male  and  female  elements.     That  it  does  exist  in  certain  cells  of  plants 
is  evident  from  the  fact  that  cuttings  produce  roots,  and  Avhen  a  stem  is 
cut  across  new  shoots  appear  from  the  lateral  buds.     Almost  any  part  of 
the  leaf  of  a  Begonia,  if  suitably  planted,  will  give  origin  to  a  fully- 
formed  plant.     Similar  phenomena  may  be  observed  in  certain  ani- 
mals— more  especially  in  amphiliians.     If  the  limb  of  a  salamander  be 
removed,  the  limb  may  be  reneAved,  that  is  to  say,  the  cells  forming  the 
various  tissues  of  the  stump  possess  the  power  of  producing  cells  of  the 
same  kind,  and   of  rebuilding  the  limb.     This  has  been  aptly  compared 
by  Pfluger,^  to  the  growth  of  a  crystal.     A  crystal  of  alum  has  a  certain 
molecular  structure,  and  if  a  small  fragment  of  such  a  crystal  is  placed 
in  a  saturated  solution  of  the  same  salt,  the  broken  fraginent  is  repaired, 
so  as  to  form  a  perfect  crystal.     This  is  more  than  an  analogy.     The 
molecular  processes  of  the  crystal  are  the  cause  of  the  deposition  of  the 
particles  of  alum  in  such  an  order  as  to  renovate  the  crystal ;  and,  in 
like  manner,  the  molecular  processes  in  the  cells  of  the  outermost  layer 

^  Pfliiger,    Ueber  den  Einfluss  dtr  Schirerkraft  auf  die   Theilimg  der  Zellen  und 
ail/die  EntwicMunrj  de-s  Embryo.     Archivf.  Physiol,  vol.  xxxii. 


PHYSIOLOGICAL  BASIS  OF  HEREDITY.  237 

of  the  stump  lead  to  the  formation  of  new  cells  of  the  same  kind  out  of 
the  material  furnished  by  the  blood  plasma  in  their  vicinity. 

Seizing  hold  so  far  of  Naegeli's  idea,  Strasburger  ^  has  modified  it,  and 
made  the  position  more  intelligible.  Like  him,  he  considers  protoplasm 
as  consisting  of  two  substances,  a  nutritive  hyaloplasm,  and  a  formative 
hyaloplasm ;  but  he  identifies  the  formative  hyaloplasm  ^viih  the 
chromatin  filament  of  the  nucleus,  which  we  have  already  studied. 
This  substance  he  called  nucleoplasm  or  nucleohyaloplasm.  It  is  the 
active  substance  in  the  nucleus  and  even  in  the  protoplasm  around  the 
nucleus,  as  Goodsir  long  ago  stated.  All  the  metabolic  changes  in  the 
cell  substance  are  controlled  and  directed  by  the  nucleoplasm.  Stras- 
burger states  that  the  reproductive  power  of  a  cell  depends  on  its  being 
in  the  embryonic  state,  and  in  plants  reproductive  cells  in  this  sense  are 
not  uncommon,  seeing  that  many  parts  of  plants  are  capable  of  vegeta- 
tive reproduction. 

This  view  throws  light  upon  the  phenomena  of  the  expulsion  of  polar 
iDodies  from  the  o\aim,  and  from  the  spermatozoid  substance.  These 
phenomena  exjjress  the  return  of  the  cells  to  their  embryonic  conditions. 
The  late  F.  M.  Balfour  held  that  the  extrusion  of  the  polar  bodies  from 
the  ovum,  or  rather  the  extrusion  of  a  part  of  the  germinal  vesicle,  was 
"  requisite  for  its  functions  as  a  complete  and  independent  nucleus," 
.  .  .  "to  make  room  for  the  supply  of  the  necessary  parts  to  it  again 
by  the  spermatic  nucleus.  My  view,"  he  says,  "amounts  to  the  follow- 
ing, viz. :  that  after  the  formation  of  the  polar  cells,  the  remainder  of 
the  germinal  vesicle,  with  the  o\aim  (the  male  pronucleus),  is  incapable 
of  further  development  without  the  addition  of  the  nuclear  part  of  the 
male  element  (spermatozoon),  and  that  if  polar  cells  were  not  formed, 
parthenogenesis  might  normally  occur.  A  strong  support  for  this 
hypothesis  would  be  afforded  were  it  to  be  definitely  established  that 
a  polar  body  is  not  formed  in  Arthropoda  and  Eotifera,  since  the 
normal  occurrence  of  parthenogenesis  is  confined  to  these  groups.  It  is 
certainly  a  remarkable  coincidence  that  they  are  the  only  two  groups 
in  which  polar  bodies  have  not  so  far  been  satisfactorily  observed." 
Further,  he  says,  "The  function  of  forming  polar  cells  has  been 
acquired  by  the  ovum  for  the  express  purpose  of  preventing  partheno- 
genesis." - 

^  >Strasburger,  JS^eiie  Uiitersuchungpn  fiber  den  Befruchtuiuiscorgang  hei  den  Phan- 
erogamen  als  Grundlage  fiir  eine  Theorie  der  Zeugung.     Jena,  1884. 

-  F.  M.  Balfour,  Comparative  Embryology,  vol.  i.  p.  72.  It  is  only  right  to  note 
that  this  theory  is  strongly  opposed  by  Carnoy,  and  that  he  especially  disputes  the 
correctness  of  the  interpretation  of  the  extrusion  of  the  polar  bodies,  La  Cyto- 
dierese  de  I'ceuf,  La  Cellule.      Tome  iii.  fasc.  i.  p.   60.     It  is  also  asserted  that- 


238  T'iii^  PHYSIOLOGY  OF  THE  TISSUES. 

This  notion,  which  has  been  somewhat  modified  by  various  authors, 
and  is  refused  by  Carnoy  as  an  explanation,  is  that  the  extrusion  of  the 
polar  bodies  from  the  nucleus  of  the  ovum  is  the  removal  of  the  male 
idioplasm,  so  that  what  is  left  is  truly  female,  and  the  extrusion  of  the 
l)article  from  the  spermatozoid  is  the  removal  of  the  female  idioplasm, 
so  that  what  remains  is  truly  male.  The  female  idioplasm  Avould  thus 
transmit  peculiarities  of  the  mother,  whilst  the  male  idioplasm  would  send 
on  those  of  the  father.  But,  as  Strasburger  and  Yon  Kolliker  acutely 
remark,  the  mother  transmits  not  oidy  her  own  peculiarities,  but  also 
those  possibly  of  the  maternal  grandfather  and  of  the  maternal  great- 
•■■randfather ;  and,  on  the  other  hand,  the  father  may  send  onward  traits 
of  the  paternal  grandmother  and  of  the  paternal  great-grandmother. 
The  maternal  idioplasm  cannot,  therefore,  be  regarded  as  entirely 
female,  nor  the  paternal  as  entirely  male.  Strasburger  holds  that  the 
nucleoidioplasm  filament  may  be  regarded  as  made  up  of  a  number  of 
segments  derived  from  previous  generations,  and  that  in  certain  circum- 
stances one  portion  may  influence  the  kytoplasm  of  the  ovum  more  than 
the  other,  thus  giving  rise  to  a  manifestation  of  some  of  the  hereditary 
qualities  of  the  particular  generation  to  which  the  portion  of  nucleohyalo- 
plasm  corresponded.  It  appears  to  me  that  here  Strasburger  passes 
entirely  into  the  region  of  theory.  The  one  statement  of  importance  in 
his  theory  is  the  identification  of  the  idioplasm  of  Naegeli,  or,  as  he  terms 
it,  the  nucleohyaloplasm  Avith  the  chromatin  filament.  It  is  at  this  point 
that  the  important  observations  of  E.  van  Beneden  come  in  Avith  great 
effect.  If  it  be  the  case  that  the  chromatin  filaments  from  the  male  and 
those  from  the  female  remain  distinct,  and  are  communicated  in  equal 
amounts  to  the  nuclei  formed  by  the  division  of  the  fecundation  nucleus, 
and  if  this  process  be  multiplied  indefinitely  in  the  formation  of  the  cells 
of  the  body,  Ave  see  that  each  cell  is  representative  of  both  father  and 
mother,  to  a  greater  or  less  extent,  according  to  the  amount  of  maternal 
and  paternal  idioplasm  present  (Fig.  112).  Further,  it  is  necessary  to 
assume  that  this  idioplasm  is  capable  by  nutrition  of  being  increased  in 
quantity,  but  by  the  action  of  surrounding  conditions  it  may  be 
acquiring  properties  peculiar  to  itself,  giving  rise  to  the  indiAaduality  of 

Weismann  has  seen  polar  bodies  extruded  from  the  eggs  of  certahi  crustaceans 
that  are  parthenogenetic  (Weismann,  Pdch.tun(jf<hiJrx>e.r  bei  partlienogeneflschen  Mem. 
Zool.  Anz.  27th  Septr.  1SS6).  Ea^cu  if  this  be  the  case  it  does  not  seem  to  me  to 
destroy  the  A-alidity  of  Balfour's  theory,  but  only  to  show  that  it  is  less  extensive 
in  its  application.  The  extrusion  of  polar  bodies  by  parthenogenetic  ova  may  be 
the  survival  of  an  ancestral  habit,  and  possibly  after  remoA^al  of  the  polar  body 
there  may  still  be  enough  of  the  male  matter  left  to  alloAV  of  development  going  on, 
Avithout  the  entrance  of  a  fresh  spermatozoid. 


PHYSIOLOGICAL  BASIS  OF  HEREDITY.  239 

the  person  in  whose  body  these  changes  are  supposed  to  take  place. 
A  time  comes,  however,  when  cells  lose  the  power  of  thus  multiplying 


Fig.  112. — Different  arrangements  of  the  primary  chromatin  loops  in  the  equatorial 
plane  of  the  egg  of  Ascaris  inegalocephaia. 

indefinitely  by  fission,  the  growth  of  the  body  is  arrested,  and  the  general 
characters  of  the  individual  are  fixed.  One  can  suppose,  then,  that  if 
any  cell  in  the  body  could  get  rid  of  its  male  portion  of  idioplasm,  and 
if  another  got  rid  of  its  female  portion,  the  two  remaining  parts  might 
conjugate,  and  the  process  of  cell  division  might  start  afresh.  The 
stimulus  would  still  be  greater  if  the  two  idioplasms  were  more  different 
than  is  likely  to  be  the  case  if  obtained  from  the  cells  of  the  same 
individual.  The  best  efi'ect  would  be  produced  if  a  certain  amount  of 
difference  existed,  and  this  is  attained  by  the  idioplasm  of  two  individuals 
being  brought  into  contact.  May  not  this  be  the  key  to  the  advantage 
gained  by  sexual  difference,  and  may  it  not  explain  the  infertility  that 
results  if  two  idioplasms  from  two  individuals  too  closely  related  be 
brought  into  mutual  relationship  ?  This  rendering  and  expansion  of 
Strasburger's  theory  I  have  reached  after  a  careful  consideration  of  the 
question  in  the  light  of  the  facts  of  modern  investigation. 

The  peculiarity  of  Strasburger's  view  is  that  the  object  of  the 
extrusion  of  the  polar  bodies  is  simply  the  attainment  of  the  embryonic 
condition,  and  that  the  reproductive  matter — call  it  idioplasm  or  any 
name  you  choose — is  formed  by  the  conversion  of  somatic  into  repro- 
ductive idioplasm.  In  the  latter  statement  Strasburger  follows  ISTaegeli. 
The  essential  distinction  between  Strasburger  and  Naegeli  is  that  while 
the  conceptions  of  the  former  are  structural  and  material,  those  of  the 
latter  are  dynamical.  This  supposed  conversion  of  somatic  into  repro- 
ductive idioplasm  is  a  difficulty,  and  a  consideration  of  it  has  led  Weis- 
mann^  to  promulgate  the  theory  of  what  is  termed  the  continuity  of  the 
germ-plasma.  This  view  is  that  heredity  consists  in  the  transmission  of 
a  nuclear  substance  of  special  molecular  structure,  not  the  idioplasm  of 
Naegeli,  nor  the  nucleohyaloplasma  of  Strasburger  (identical  mth 
chromatin),  but  a  substance  special  and  f)eculiar  to  the  germinative  cells. 

■■■  August  Weismann,  Die  continuitat  des  Keimplasma's  als  Grundlage  einer 
Theorie  der  Vererbung.  Jena,  1885.  See  also  an  account  of  this  memoir  by 
Professor  H.  N.  Moseley  in  Nature,  vol.  xxxiii.  p.  154, 


240  THE  rilYSlOLOGY  OF  THE  TISSUES. 

This  luiclear  matter  which  he  calls  keimplasma,  germ-plasma,  is  passed 
on  from  generation  to  generation  without  alteration  ;  it  is  therefore  con- 
tinuous and  inmiortal  if  individuals  do  not  fail  in  propagating  their 
species.  This  specific  germ-plasma,  derived  from  the  male  and  female 
parents,  is  not  entirely  used  up  in  the  development  of  the  offspring,  but 
a  portion  of  it  is  set  aside  to  form  the  germ-plasma  of  the  next  generation. 
According  to  this  view,  the  germ-plasma  is  in  no  way  derived  from  the 
somatic-plasma ;  each  has  an  independent  existence  ;  l)ut  while  the 
somatic-plasma  cannot  influence  the  germ-plasma,  the  portion  of  germ- 
l)lasma  not  laid  aside  to  form  the  germ-plasma  of  the  next  generation 
exercises  a  potent  influence  over  the  development  of  the  somatic-jjlasma, 
transmitting  to  it  the  characters  of  the  parents.  Professor  Weismann 
supports  this  view  with  many  striking  illustrations,  and  he  adapts  the 
theory  to  the  explanation  both  of  the  extrusion  of  polar  bodies  and  of 
l)arthenogenesis.  Thus  the  o^^^lm  has  two  kinds  of  plasma  in  it,  histo- 
genetic  or  somatic-plasma  and  true  germ-plasma.  In  its  early  stages, 
the  histogenetic  plasma  is  engaged  in  forming  the  yolk  and  membranes, 
and  as  it  is  of  no  further  use  in  the  further  development  of  the  embryo, 
it  is  got  rid  of  in  the  form  of  one  or  more  polar  bodies  to  make  room  for 
fresh  histogenetic  plasma,  derived  in  turn  from  the  germ-plasma  of  the 
spermatozoon.  The  polar  bodies  are  thus  ovogenous  nucleo-plasma,  got 
rid  of  to  allow  new  nucleo-plasma  to  have  free  play.  A  similar 
explanation  applies  to  the  separation  of  particles  from  the  male  sperm 
cell. 

As  to  parthenogenesis,  AVeismann  supposes,  in  the  first  place,  that  the 
male  and  female  elements  in  fecundation,  that  is  to  say,  the  germ-cell 
and  the  sperm-cell,  are  practically  identical,  and  that  after  the  extrusion 
of  the  polar  bodies,  development  is  started  by  the  sudden  addition  to  the 
so-called  female  element  of  the  so-called  male  element.  This  sudden 
addition  necessitates  cleavage,  and  as  nutrition  goes  on  actively,  for  the 
same  reason,  cleavage  goes  on  again  and  again  to  form  the  embryonic 
cells.  In  some  ova,  however  (parthenogenetic  ova),  even  after  the 
extrusion  of  polar  bodies,  nutrition  goes  on  so  actively  as  to  start  the 
developmental  process  without  the  stimulus  caused  by  the  suddeii 
addition  of  the  so-called  male  element.  Pai'thenogenesis,  according  to 
this  view,  is  thus  merely  a  modification  of  the  power  of  growth.  The 
theory  is  not  open  to  the  objection  urged  against  that  of  F.  M.  Balfour, 
namely,  the  undoubted  extrusion  of  polar  bodies  from,  at  all  events, 
some  parthenogenetic  ova. 

It  appears  to  me,  however,  that  this  theory,  so  ably  maintained  by 
AVeismann,  while  it  undoubtedly  removes  some  of  the  difficulties,  leaves 
the  facts  of  hereditary  transmission  unexplained.    If  the  portion  of  germ- 


PHYSIOLOGICAL  BASIS  OF  EEREBITT.  241 

plasma  not  laid  aside  influences  the  development  of  the  body,  conferring 
on  each  tissue  and  organ  at  least  some  of  the  proclivities  of  the  parent, 
how  does  it  do  so  ?  The  molecular  mechanism  by  which  this  is 
accomplished  is  inexplicable.  On  the  other  hand,  if  this  germ-plasma 
does  not  so  influence  development,  how  are  the  facts  of  hereditary 
transmission  to  be  explained  %  It  is,  I  humbly  think,  cpiite  possible  that 
AYeismann  may  be  right  in  the  conjecture  that  a  portion  of  the  original 
germ-plasma  may  be  laid  aside  at  the  earliest  period  of  development  to 
constitute  the  germ-plasma  of  the  next  generation ;  but  surely  this 
germ-plasma  has  received  a  molecular  imprint  from  the  parent  in  whose 
body  it  at  one  time  existed  so  that  it  transmits  certain  of  the  character- 
istics of  that  parent.  If  the  germ-plasma  cannot  be  altered,  how  are  we 
to  account  for  the  transmission  of  special  characters  of  any  kind  ? 
AYeismann  has  admitted  this  difficulty  by  denying  the  alleged  trans- 
mission of  acquired  characters  by  sexual  reproduction ;  but  all  characters 
must  have  been  acquii'ed  at  one  time  or  another,  and  any  organism  is 
what  it  is  at  the  present  moment,  in  consequence  of  this  transmission  of 
acquired  peculiarities  through  countless  generations.  The  germ-plasma 
cannot  then  remain  the  same,  and  therefore  the  only  way  in  which  we 
can  suppose  it  to  be  modified  is  through  the  agency  of  the  idioplasm 
throughout  the  body.  This  view  Avill  explain  to  some  extent  at  least 
the  transmission  of  acquired  characters.^ 

In  all  these  discussions,  one  aspect  of  the  subject,  as  it  relates  to  the 
higher  organisms,  and  especially  to  man,  is  often  omitted,  namely,  the 
influence  Avhich  the  female  parent  exerts  on  the  development  of  the  off- 
spring, while  in  the  uterus,  in  consequence  of  the  intimate  union  that 
exists  for  a  considerable  period  of  time.  It  is  a  familiar  observation 
that  animals  reared  outside  the  mother's  body,  as  in  most  invertebrates, 
in  fishes,  amphibians,  and  birds,  are  remarkably  similar  to  each  other. 
The  individuals  in  a  shoal  of  fish  or  a  flock  of  sea  gulls  or  sparrows  can 
scarcely  be  distinguished.     It  is  when  we  reach  the  stage  of  develop- 

^  I  have  to  express  my  admiration  of  Weismann's  theory  as  a  guide  to  an  experi- 
mental investigation  into  this  most  difficult  field  of  inquiry.  I  would  further 
observe  that  it  can  hardly  be  expected  that  acquired  characters  in  their  full  intensity 
■will  be  transmitted  to  the  immediately  succeeding  generation,  seeing  that  the 
ova  destined  to  become  the  individuals  of  that  generation  are  found  in  the  ovary 
of  the  mother  during  embryonic  life.  The  influence  of  an  acqiiired  character  might 
have  a  certain  effect  on  the  ova  during  the  life  of  the  mother,  but  not  enough  to 
reproduce  the  acquired  character  with  any  degree  of  strength  in  the  ofispring.  If 
the  influences  producing  the  acquired  character  acted  also  on  the  offspring,  its 
effect  on  the  offspring  of  the  third  generation  would  be  intensified,  and  thus  a  pro- 
cess of  accretion  during  several  generations  may  be  required  to  stamp  acquired 
characters  on  offspring. 

I.  Q 


242  THE  PHYSIOLOGY  OF  THE  TISSUES. 

ment  by  placental  connection  that  we  begin  to  observe  diversity  of 
appearance,  and  if  along  with  this  we  suppose  that  in  consequence  of  a 
great  development  of  the  nervous  system,  the  female  becomes  more  and 
more  susceptible  to  external  impressions  Avhich  react  on  her  body  and 
through  her  body  on  her  offspring  in  utero,  an  explanation,  so  far,  of 
individual  peculiarities  of  the  human  race  becomes  apparent.  There 
can  be  no  doubt  that  pregnancy  makes  a  remarkable  change  on  the 
mother,  to  such  an  extent  that  the  characters  of  subsequent  offspring 
may  be  influenced.  Thus  it  is  well  knoA\'n  to  breeders  of  animals  that 
a  pregnancy  induced  by  a  certain  kind  of  male,  may  deteriorate  the 
characters  of  offspring  that  owe  their  origin  to  subsequent  impregna- 
tions by  other  males.  It  is  possible,  therefore,  that  not  a  few  maternal 
characters  may  arise  in  this  way,  and  that  if  we  could  hatch  human 
beings  as  we  can  hatch  eggs,  human  beings  might  be  so  similar  in 
appearance  as  to  be  practically  indistinguishable.-' 

There  is  still  one  other  view  of  the  matter  which  I  shall  briefly 
notice.  If  the  germinal  vesicle  be  only  the  1-5  00th  of  an  inch,  and  the 
head  of  the  spermatozoid  be  only  the  l-62.50th  of  an  inch  in  diameter, 
dare  we  suppose,  on  purely  physical  grounds,  that  so  small  a  particle  of 
matter  as  is  formed  by  the  union  of  the  two  can  contain  a  sufficient 
number  of  organic  molecules  to  account  in  any  way  for  the  transmission 
of  hereditary  peculiarities  1  The  late  Professor  Clerk  Maxwell,  in  his 
profoundly  interesting  article  on  the  Atom  in  the  Encydopcedia  Britan- 
nica,  thus  states  the  case — 

"  The  first  numerical  estimate  of  a  diameter  of  a  molecule  was  that  made  by 
Loschmidt,  in  1865,  from  the  mean  path  aud  the  molecular  volume.  Independently 
of  him,  and  of  each  other,  Mr.  Stoney,  in  1868,  and  Sir  W.  Thomson,  in  1870, 
published  results  of  a  similar  kind— those  of  Thomson  being  deduced  not  only  in 
this  way,  but  from  considerations  derived  from  the  thickness  of  soap  bubbles,  and 
from  the  electric  action  between  zinc  and  copper. 

"  The  diameter  and  the  mass  of  a  molecule,  as  estimated  by  these  methods,  are 
of  course  very  small,  but  by  no  means  infinitely  so.  About  two  millions  of  mole- 
cules of  hydrogen  in  a  row  would  occupy  a  millimetre,  and  about  two  hundred 
million  million  million  of  them  would  weigh  a  milligramme.  These  numbers 
must  be  considered  as  exceedingly  rough  guesses  ;  they  must  be  corrected  by 
more  extensive  and  accurate  experiments  as  science  advances  ;  but  the  main 
result,  which  appears  to  be  well  established,  is  that  the  determination  of  the 
mass  of  a  molecule  is  a  legitimate  object  of  scientific  research,  and  that  this  mass 
is  by  no  means  immeasurably  small. 

"Loschmidt  illustrates  these  molecular  measurements  by  a  comparison  with 
the  smallest  magnitudes  visible  by  means  of  a  microscope.     Nobert,  he  teUs  us, 

^  A.  Harvey.  1,  Relative  influence  of  male  and  female  parents,  Monthly  Journal 
of  Mediccd  Science,  1854.  2,  On  the  foetus  in  utero,  Edinburgh,  1850.  3,  Foetus 
In  utero,  Glasgow,  1859. 


PHYSIOLOGICAL  BASIS  OF  HEREDITY.  243 

•can  draw  4,000  lines  in  the  breadth  of  a  millimetre.  The  interval  between  these 
lines  can  be  observed  with  a  good  microscope.  A  cube,  whose  side  is  the  4,000th 
•of  a  millimetre,  may  be  taken  as  the  minimum  visible  for  observers  of  the  present 
■day.  Such  a  cube  would  contain  from  60  to  100  million  molecules  of  oxygen  or  of 
nitrogen  ;  but,  since  the  molecules  of  organized  substances  contain  on  an  average 
■about  50  of  the  more  elementary  atoms,  we  may  assume  that  the  smallest 
organized  particle  visible  under  the  microscope  contains  about  two  million  mole- 
•cules  of  organic  matter.  At  least  half  of  every  living  organism  consists  of  water, 
so  that  the  smallest  living  being  visible  under  the  microscope  does  not  contain 
more  than  about  a  million  organic  molecules.  Some  exceedingly  simple  organism 
may  be  supposed  built  up  of  not  more  than  a  million  similar  molecules.  It  is 
impossible,  however,  to  conceive  so  small  a  number  sufficient  to  form  a  being 
furnished  with  a  whole  system  of  specialized  organs.  Thus  molecular  science  sets 
us  face  to  face  with  physiological  theories.  It  forbids  the  physiologist  from 
imagining  that  structural  details  of  infinitely  small  dimensions  can  furnish  an  ex- 
planation of  the  infinite  variety  which  exists  in  the  properties  and  functions  of 
"the  most  minute  organism. 

"A  microscopic  germ  is,  we  know,  capable  of  development  into  a  highly 
organized  animal.  Another  germ,  equally  microscopic,  becomes,  when  developed, 
■an  animal  of  a  totally  different  kind.  Do  all  the  differences,  infinite  in  number, 
which  distinguish  the  one  animal  from  the  other,  arise  each  from  some  difference 
in  the  structure  of  the  respective  germs  ?  Even  if  we  admit  this  as  possible,  we 
shall  be  called  upon  by  the  advocates  of  Pangenesis  to  admit  still  greater  marvels. 
Por  the  microscopic  germ,  according  to  this  theory,  is  no  mere  individual,  but  a 
Tepresentative  body,  containing  members  collected  from  every  rank  of  the  long- 
drawn  ramification  of  the  ancestral  tree,  the  number  of  these  members  being  amply 
sufBcient  not  only  to  furnish  the  hereditary  characteristics  of  every  organ  of  the 
body,  and  every  habit  of  the  animal  from  birth  to  death,  but  also  to  afford  a  stock 
■of  latent  gemmules  to  be  passed  on  in  an  inactive  state  from  germ  to  germ,  till  at  last 
the  ancestral  peculiarity  which  it  represents  is  revived  in  some  remote  descendant. 

"  Some  of  the  exponents  of  this  theory  of  heredity  have  attempted  to  elude  the 
•difficulty  of  placing  a  whole  world  of  wonders  within  a  body  so  small  and  so 
■devoid  of  visible  structure  as  a  germ,  by  using  the  phrase  structureless  germs. 
(See  F.  Galton  on  "Blood  Relationship,"  Proc.  Roy.  Soc,  June  13,  1872.)  Now, 
■one  material  system  can  differ  from  another  only  in  the  configuration  and  motion 
which  it  has  at  a  given  instant.  To  explain  diflferences  of  function  and  develop- 
ment of  a  germ  without  assuming  differences  of  structure  is,  therefore,  to 
admit  that  the  properties  of  a  germ  are  not  those  of  a  purely  material  system." 

It  is  since  that  article  was  published  in  1875,  that  most  of  the  results 
■detailed  in  Chap.  II.  (p.  214),  have  been  reached.  The  opinions  expressed 
by  the  eminent  physicist  require  modification  in  the  light  of  more  recent 
research.  Neither  ovum  nor  spermatozoid  is  now  to  be  regarded  as 
destitute  of  structure,  and  the  tendency  of  research  is  to  show  that  the 
peculiarities  of  different  ova  depend  on  differences  of  molecular  struc- 
ture. Further,  small  as  the  reproductive  body  formed  by  the  fusion  of 
the  male  and  female  elements  is,  it  is  still  large  enough  to  contain 
millions  of  organic  molecules  having  a  complexity  of  structure  as  great 


244  THE  PHYSIOLOGY  OF  THE  TISSUES. 

as  that  of  a  molecule  of  albumin.  The  physiologist  also  lays  stress  on 
the  fact  that  all  the  tendenc}-  of  his  -work  on  these  miiu;te  structures  is 
in  the  direction  of  detecting  diffcrmces,  not  necessarily  i)hysical  in  the 
sense  of  being  discernible  by  an}'  possible  microscope,  but  differences  of 
a  chemical  nature — in  other  words,  molecular.  Xor  arc  the  tissues  so- 
various,  nor  the  individual  peculiarities  so  numerous,  as  the  phA'sicist  is. 
apt  to  suppose.  ]\Iuch  depends  on  vegetative  repetition,  so  that,  given 
the  peculiarities  of  an}'  indiAndual,  it  is  not  improbable  that  a  few 
thousand  special  types  of  cell  formation,  as  regards  molecular  structiu-e,. 
would  be  sufficient  to  accoimt  for  the  special  peculiarities.  There  is. 
room  enough  for  many  such  molecules  in  a  cube  of  idioplasm  having  a 
side  of  l-500th  of  an  inch. 

For  bibliographical  references  to  the  subjects  discussed  iu  the  three  preceding 
chapters,  see  a  paper  by  the  author,  on  "  The  Modern  Cell  Theory,"  in  the  Pro- 
ceedinrjs  of  the  Philosophical  Society  of  Glasgow,  Vol.  XX. 

Chap.  IV.— FORMATIOX  OF  THE  BLASTODERMIC  LAYERS. 

Having  considered  the  phenomena  that  immediately  follow  the 
union  of  the  o\iim  and  spermatozoid,  we  shall  next  direct  our  attention 
to  the  earlier  differentiation  of  the  embryonal  cells  into  the  layers  from 
which  the  tissues  and  organs  are  developed.  This  can  be  done  Avithout 
discussing  difficult  embryological  questions,  and  -wdthout  entering  much, 
into  detail ;  and  it  is  ini})ortant  to  follow  this  course,  because  it  will 
enable  us  to  classify  the  tissues  genetically  and  to  observe  relations- 
existing  between  tissues  in  the  embryonal  condition  that  would  not  be 
suspected  when  we  contrast  their  characters  as  seen  in  fully  formed  tissue.^ 

As  already  explained  in  Chap.  II.  of  this  section,  p.  214,  the  phenomena 
of  fecimdation  are  followed  by  segmentation  in  which  the  ovum  divides, 
into  tAvo,  then  into  four,  eight,  sixteen,  etc.,  cells  (Fig.  111).  At  the  end 
of  the  segmentation  process,  the  ovum  consists  of  a  sphere  formed  of 
primitive  cells,  or  blastomeres,  of  uniform  size,  and  these  cells  are 
arranged  in  a  single  layer  to  form  a  Avail  around  a  central  cavity.  The 
Avail  of  the  oAiim  is  noAV  called  the  Uastoderrii,  or  germinal  membrane,. 
and  the  caAdty  in  the  centre  is  the  segmentation  cavity  of  Von  Baer> 
This  is  the  arrangement  in  the  early  development  of  Amphioxus,  the 
most  primitive  vertebrate,  in  Avhich  the  stages  are  simple  and  easily 
understood.  One  side  or  wall  of  the  blastosphere  then  becomes- 
thickened  and  invaginated,  so  as  to  give  rise  to  a  layer  of  cells  forming 
a  lining  to  the  outermost  layer.     The  embryo  has  noAv  the  form  of  a 

^  Details  as  to  the  formation  of  organs  and  as  to  the  formation  of  the  embryonal 
vesicles  will  be  given  in  discussing  the  reproductive  process.  It  is  not  necessary 
to  allude  to  these  at  present. 


FORMATION  OF  THE  BLASTODERMIC  LAYERS. 


24^ 


sphere,  the  wall  of  which  is  formed  of  two  layers,  an  outer,  termed  the 
epiblast  or  ectoderm,  and  an  inner,  termed  the  hypoblast  or  endoderm,  and 
the  cavity  or  space  in  the  sphere,  called  the  archenteric  cavity  or  arch- 
enteron,  communicates  with  the  exterior  by  a  small  aperture,  the 
blastopore.  At  this  stage  the  embryo  is  termed  a  (jastnda.  The  embryo 
«oon  becomes  much  elongated,  so  that  the  blastopore  is  at  first  at  the 
posterior  end,  and  a  little  later  on  is  seen  on  the  dorsal  surface.  A  groove 
now  forms  on  the  dorsal  surface  of  the  elongated  embryo  by  the 
development  of  two  folds  of  the  epiblast.  The  lips  of  this  groove 
coalesce  so  as  to  form  a  canal,  the  neural  canal,  and  the  blastopore  opens 
aato  this  canal  by  a  foramen  or  passage,  cancdis  netirentericiis,  seen  in 
Fig.  113.     This  canal  is  closed  at  a  later  period. 


kri) 


'pSC 


-e  --     me 


Fig.  113. — A.  Longitudinal  section  of  Amphioxus.  B.  Transverse  section  of  Amphioxus. 
■ep,  epiblast ;  hyp,  hypoblast ;  me,  mesoblast ;  ps,  first  primitive  segment ;  psc,  cavity  in 
pi'imitive  segment ;  ic,  archenteric  cavity  ;  n,  primitive  neural  canal ;  en,  cancdis  nev/r- 
enteHcus.     An,  anterior  ;  P,  posterior  end  of  embryo. 

According  to  E.  van  Beneden,  segmentation  occurs  in  the  ovum  of 
the  rabbit  within  one  or  two  hours  after  the  union  of  the  male  and 
female  pronuclei,  and  the  whole  process  is  accomplished  within  seventy 
to  seventy-five  hours  thereafter.  In  the  segmentation  process  an  early 
•differentiation  of  cells  has  been  noticed.  Even  in  the  cleavage  of  the 
first  cell  the  result  is  the  formation  of  two  cells,  one,  the  upjDer,  some- 
what larger  than  the  other,  the  lower,  and  when  eight  cells  have  been 
formed,  the  four  lower  cells  occupy  a  more  central  position  than  the 
four  upper   cells.     Further,  the  upper   or   outer  cells  increase  more 


246 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


A. 


yc- 


MM 


g^    epi     'W'-. 


4)      I 


J'vp  — L      fi^ 


IE 


ti 


Fig.  114. — A.  Longitudinal  section  through  the  blasto- 
derm of  hen's  egg  at  end  of  first  hour.  B.  Transverse 
section  through  the  same,  epi,  epiblast,  outer  layer  ; 
hi/p,  hypoblast,  inner  layer ;  yc,  yolk  cells  ;  cf,  cres- 
centic  furrow.  To  see  these  layers  in  their  natural  posi- 
tion, turn  the  page  so  that  the  epiblast  is  uppermost. 


rai)idly  than  the  lower  or  in- 
ner cells,  so  that  the  outer 
cells  ultimately  entirely  en- 
close the  inner  cells.  The  in- 
vagination process  producing 
a  gastrula  has  not  been  seen 
in  the  mammalian  o\'T.im,  but 
there  exists  an  aperture  which 
Van  Beneden  regards  as  the- 
homologue  of  the  blastopore. 
This  aperture  is  soon  closed 
by  the  growth  of  cells  around 
it,  and  the  o'saim  of  a  mammal 
now  consists  of  a  dense  mass  of 
cells.  The  outermost  layer  is 
composed  of  cells  of  a  pris- 
matic shape. 

The  succeeding  stages  of  de- 
velopment mil  be  best  under- 
stood if  we  examine  them  in 
the  first  instance  as  they  maj' 
be  traced  in  the  egg  of  the 
common  fowl  during  incuba- 
tion. The  yolk  is  surrounded 
by  a  thin  membrane,  the 
vitelline  membrane,  and  at  one 
point  of  its  siuface  a  small 
white  disc,  about  4  mm.  in 
diameter,  may  be  seen.  This 
is  the  blastoderm  or  cicatricula, 
corresponding  to  the  layer  of 
cells  which  entirely  surrounds 
the  ovum  of  the  mammal.  In 
the  centre  of  the  blastoderm 
there  is  a  clear  transparent 
portion,  the  area  pellucida,  in 
which  the  embryo  is  formed. 
A  vertical  section  through  the 
area  pellucida  of  a  fecundated 
egg,  in  which  segmentation  has. 
taken  place,  shows  that  the 
blastoderm  is  formed  of  two 
layers.  The  upper  layer  con- 
sists  of  somewhat   elongated 


FORMATION  OF  THE  BLASTODERMIC  LAYERS. 


247 


cells,  having  their  long  axes  vertical,  and  adhering  by  their  sides. 
Those  cells  are  of  uniform  size,  about  9  /x,  and  each  shows  usually  an 
oval  nucleus.  This  layer  constitutes  the  epiblast.  The  deeper  layer  of 
the  blastoderm,  termed  the  hypoblast,  consists  of  somewhat  larger  cells, 
so  highly  granular  as  to  conceal  the  nucleus.  Between  the  blastoderm 
and  the  underlying  yolk  there  is  a  space,  the  homologue  of  the  segmen- 
tation cavity  to  which  reference  has  already  been  made.  See  Figs.  114 
and  115. 

After  a  few  hours  of  incubation,  the  area  pellucida  loses  its  circular 


Fig.  115. — Three  transverse  sections  through  an  egg  in  whicli  the 
medullary  ridge  is  beginning  to  form.  The  sections  show  the  stages 
in  the  development  of  the  chorda  dormlis,  and  the  formation  of  the 
two  layers  of  the  mesoblast.  ep,  epiblast ;  hyp,  hypoblast  ;  pi, 
parietal  layer  of  mesoblast ;  vl,  visceral  layer  of  mesoblast ;  mp, 
medullary  plates  ;  7/i/,  medullary  folds  ;  c/i,  chorda;  6c,  body  cavity 
or  pleuro-peritoneal  cavity. 

outline  and  becomes  oval  and  then  pear-shaped,  and  toAvards  the  narrow 
end  of  the  pear-shaped  area  an  opaque  thickened  portion  makes  its 


248 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


appearance.  This  is  the  primitive  streak  or  trace.  A  groove — the 
primitive  groove — then  appears  on  the  iipper  surface  of  the  streak. 
Abont  this  period,  that  is  to  say,  between  the  eighth  and  twelfth  hour 
of  incubation,  a  middle  hxyer  of  the  blastoderm — the  wesohlast  or  7nemderm 
— begins  to  be  formed.  The  primitive  streak  is  a  mass  of  cells  arising 
from  proliferation  of  cells  derived  from  the  epiblast,  and  may  be  regarded 
as  the  commencement  of  the  middle  la3"er  in  connection  Avith  the  epiblast. 
About  the  sixteenth  hour,  tAvo  ridges  or  folds  of  the  epiblast  rise  on  each 
side  of  the  primitive  streak.  These  ridges,  termed  the  dorsal  ridges  or 
medidlary  folds,  enclose  plates  known  as  the  meduHary  plates,  and  the 
ridges  ultimately  coalesce  so  as  to  form  a  closed  tube — the  neural  canal 
— giving  origin  to  the  primitive  cerebro-spinal  axis.  Below  the  medul- 
lary tube  thus  formed,  the  chorda  dorsalis  or  notochord,  an  elongated 
cartilaginous  rod,  appears,  and  this  becomes  the  centres  of  the  bodies  of 
the  permanent  vertebrae  and  the  basis  of  the  cranium.  Some  of  these 
structures  are  seen  in  Fiais.  115  and  116. 


Fig.  1H3. — Two  transverse  sections  through  the  embryo  of  a  Xewt.  A, 
Transverse  section  through  the  body,  in  which  the  neural  canal  is 
not  yet  closed  and  the  primitive  segments  are  beginning  to  separate 
from  the  ventral  lamina;.  B,  Transverse  section  in  which  the  neural 
canal  is  closed  and  the  primitive  segments  are  fully  formed,  mf, 
medullary  folds  ;  Tii^),  medullary  plate  ;  n,  nervous  tube;  ch,  chorda 
dorsalis;  ep,  epiblast;  pi,  parietal  layer  of  mesoblast ;  vl,  visceral 
layer  of  mesoblast ;  ic,  intestinal  canal ;  be,  body  cavity  ;  psc,  cavity 
in  primitive  segment ;  yc,  yolk  cells. 


FORMA  TION  OF  THE  BLASTODERMIC  LA  YERS. 


249 


As  already  pointed  out,  the  mesoblast  arises  chiefly  from  the  deeper 
layer  of  cells  of  the  epiblast,  but  according  to  F.  M.  Balfour  and  His,  it 
proceeds  also  in  part  from  the  hypoblast  and  from  nuclei  in  the  germinal 
Avail  of  the  yolk  at  the  outer  surface  of  the  latter.  The  mesoblast,  in 
turn,  divides  into  two  layers,  an  outer,  termed  the  somatic  or  joarietal 
mesoblast  or  somatopleure,  which  uniting  with  the  epil^last  gives  origin  to 
the  osseous,  fibrous,  muscular,  and  tegumentary  substance  of  the  body- 


Fig.  UV. — Diagram  showing  the  development  of  the  meso- 
blast and  of  the  body  cavity  in  the  vertebrata.  Trans- 
verse section  through  the  blastopore  of  an  embryo,  bp, 
blastopore  ;  jnc,  primitive  intestinal  cavity  ;  he,  body 
cavity ;  y,  yolk ;  epi,  epiblast ;  pi,  parietal  layer  of 
mesoblast ;  vl,  visceral  layer  of  mesoblast. 


Fig.  lis. — Diagram  of  the  aevelopment  of  the  mesoblast 
and  of  the  body  cavity  of  a  vertebrate.  Transverse 
section  through  an  embryo  in  front  of  the  blastopore, 
i/ip,  medullary  plate  ;  ch,  beginning  of  the  chorda  dorsalis  ; 
ep,  outer  germinal  layer  or  epiblast ;  hyp,  inner  germinal 
layer  or  hypoblast ;  pi,  parietal  layer  of  middle  germmal 
layer  or  mesoblast ;  vl,  visceral  layer  of  middle  germinal 
layer  or  mesoblast;  y,  yolk  ;  ic,  intestinal  canal ;  be,  body 
cavity. 

wall  and  limbs ;  and  an  inner,  the  visceral  mesoblast  or  splanchnopleure, 
which,  uniting  with  the  hypoblast,  forms  the  fibrous  and  muscular  wall 


250  THE  PHYSIOLOGY  OF  THE  TISSUES. 

of  the  alimentary  canal,  the  hnnph  and  blood-vascular  system,  and  the 
urinarj'  and  generative  organs.  Between  the  two  layers  of  the  meso- 
blast  we  have  the  general  pleuro-peritoneal  space  or  the  body-cavity. 
The  formation  of  these  layers  is  well  shown  in  Figs.  117  and  118. 

The  mesoblast  in  amphioxus,  instead  of  arising  from  the  epiblast, 
originates  in  two  diverticula  or  recesses  constricted  off  from  the  archen- 
teric  cavity,  and  the  notochord  is  also  developed  from  a  third  diverti- 
culum springing  from  the  dorsal  aspect  of  the  archenteric  cavity,  a  type 
of  development  met  A\ath  in  various  invertebrate  forms.  This  is  shown 
in  Fig.  119. 


Pio.  119. — Transverse  section  through  embryo  of  Amphi- 
oxus. ep,  epiblast ;  me,  mesoblast ;  hyp,  hypoblast ; 
mp,  merlullary  or  neural  plate  ;  ch,  chorda  dorsalis  ;  ac, 
archenteric  cavity  ;  be,  body  cavity. 

The  vesicular  form  of  the  blastoderm  of  mammals,  arising  from  the 
segmentation  of  the  entire  yolk  instead  of  segmentation  of  only  a  por- 
tion of  it,  as  occurs  in  the  egg  of  the  common  fowl,  causes  certain 
modifications  in  the  development  of  the  layers.  As  already  described, 
the  covering  of  the  ovum  consists  of  a  layer  of  elongated  nucleated  cells 
(Fig.  115),  and  in  the  interior  there  is  a  semi-fluid  mass  of  broken  down 
yolk  substance  and  some  of  the  primitive  granular  cells,  or  segmental 
sjiheres.  The  latter  by  proliferation  form  a  layer  adapted  to  the  outer- 
most layer,  and  thus  the  wall  of  the  vesicle  soon  has  two  layers.  In  the 
rabbit,  about  the  fifth  day,  and  when  the  inner  layer  of  cells  has  spread 
over  about  one  half  of  the  vesicle,  a  discoidal  thickening  or  opacity 
appears  in  the  middle  of  the  blastoderm.  This  is  the  embryonal  area 
seen  in  Fig.  1 20,  and  in  it  the  primitive  streak  and  primitive  groove  appear 
as  in  birds,  and  then  follows  the  development,  in  a  similar  manner,  of  the 
nervous  system  and  of  the  chorda  dorsalis. 

The  formation  of  the  three  layers  of  the  embryo  having  thus  been 
traced,  it  remains  to  refer  to  these  layers  the  genesis  of  the  tissues  and 
of  the  more  important  organs  of  the  body. 


FORMATION  OF  THE  BLASTODERMIC  LAYERS.  251 

1.  The  EpiUast  gives  rise  to  {a)  the  central  nervous  system  ;  from 
the  infolding  of  the  medullary  plates  to  form  the  neural  tube  (see  Fig. 
116),  the  white  and  grey  matter  of  the  brain  and  spinal  cord  is  formed ; 


Fio.  1120. — Views  of  the  Blastodermic  Vesicle  of  a  rabbit  on  the  seventh  day,  witliout 
the  znna  'pellucida,  or  outer  layer  of  the  egg.  A,  From  above ;  B,  from  side,  ag,  area, 
iu  which  embryo  appears  ;  ge,  boundary  of  the  hypoblast. 

and  (Jj)  the  sympathetic  nervous  system  and  the  peripheral  nerves,  both 
cranial  and  spinal,  and  ganglia,  are  also  derived  from  the  epiblast.  (c) 
The  ciliated  epithelium  in  the  central  canal  of  the  spinal  cord  and  in 
the  cerebral  ventricles  is  epiblastic.  (d)  The  epiblast  gives  origin  to 
the  epidermis  and  to  all  structures  of  epidermic  nature,  such  as  horn, 
hoof,  nail,  feather,  etc.,  and  also  to  the  sebaceous  and  sweat  glands. 
(e)  The  sensory  expansions  in  the  organs  of  special  sense  originate  in 
the  epiblast,  either  by  involutions  of  the  medullary  or  neural  canal 
(retina  and  pigment  epithelium  of  choroid),  or  by  involutions  of  the  ex-' 
ternal  epiblastic  layer  covering  the  embryo  (the  sensory  structures  in 
the  ear,  in  the  nose,  taste  cells,  touch  corpuscles).  (/)  The  crystalline 
lens  is  formed  of  infolded  epiblast.  {g)  The  epithelium  lining  the 
cavity  of  the  mouth  and  anus,  the  epithelium  of  the  glands  and  other 
structures  related  to  these  cavities,  the  enamel  of  tooth  and  the  salivary 
glands  are  derived  from  the  epiblast.  (li)  Lastly,  the  pituitary  body 
belongs  to  this  layer. 

2.  The  Mesohlast  gives  origin  to  (a)  the  connective  tissues ;  (b)  the 
muscles ;  (c)  the  bones  and  cartilages ;  (d)  the  heart,  arteries,  veins, 
capillaries,  lymphatics,  and  serous  membranes,  with  their  lining  cells  or 
endothelium ;  and  (e)  the  embryonic  blood  and  lymph  corpuscles.  From 
it  also  arise  (/)  the  generative  organs,  their  epithelium,  and  the  genera- 
tive elements,  ova,  and  spermatozoids ;    (g)  the  urinary  organs  and. a. 


252  THE  PHYSIOLOGY  OF  THE  TISSUES. 

\YAvt  of  the  epithelium  of  the  tubules  of  the  kidney ;  and  {h)  the  mus- 
•cvilar,  vascular,  and  coiuiective  tissue  elements  in  the  wall  of  the 
alimentary  canal  and  in  the  skin.  The  muscular  fibres  of  the  sweat 
glands  of  the  skin  are  said  to  be  epiblastic.  (/)  The  spleen  and  other 
blood  glands  also  spring  from  this  layer. 

3.  The  Hypoblast  is  the  layer  from  which  most  of  the  epithelial  struc- 
tures are  derived,  such  as  {a)  the  epithelium  of  the  alimentary  canal ; 
•(6)  the  epithelium  of  the  resjiiratory  organs,  trachea,  bronchial  tubes, 
and  pulmonary  air  cells  ;  {r)  the  epithelium  of  the  Eustachian  tube  and 
tympanum  of  the  ear ;  {<!)  the  epithelium  of  the  ducts  of  the  liver, 
jjancreas,  and  of  glands  opening  into  the  alimentary  canal ;  (e)  the  hepatic 
cells  ;  (/)  the  secreting  cells  of  the  pancreas ;  {g)  the  epithcliiim  of  the 
thyroid  body  and  of  part  of  the  thymus  gland ;  and  (Ji)  the  epithelium 
of  the  urinary  bladder  and  ureters  and  of  a  portion  of  the  tubules  of  the 
kidney ;  (i)  the  hypoblast  is  also  the  parent  of  the  notochord. 

Chap.  V.— THE  MICROSCOPE  AND  THE  METHODS  OF 
MICROSCOPICAL  RESEARCH. 

A  knowledge  of  the  minute  structure  of  the  tissues  and  of  the  organs 
•of  the  body  is  acquired  by  the  use  of  the  microscope.,  one  of  the  most  im- 
portant instruments  of  physiological  research.  The  microscope,  more 
•especially  in  recent  years,  has  been  so  much  improved,  both  in  its 
mechanical  and  in  its  optical  appliances,  that  it  may  now  be  considered 
as  the  scientific  instrument  of  all  others  that  has  almost,  if  not  quite, 
reached  perfection,  or  at  all  events  has  reached  such  a  condition,  more 
especially  as  regards  its  optical  arrangements,  that  we  can  scarcely  hope 
ix)  witness  any  marvellous  improvement.  Fiu-ther,  from  the  time  of  the 
first  enunciation  of  the  cell  theory  of  the  origin  of  tissues  in  1838,  most 
of  our  histological  knowledge  has  been  gained  bj"  instruments  of  compara- 
tively low  magnifying  power  and  with  imperfect  methods  of  ilhmiination, 
.and  it  is  only  during  the  last  few  years  that  physiologists  have  availed 
themselves  of  the  use  of  the  most  improA^ed  lenses,  of  new  methods  of 
illumination,  and  of  the  art  of  photography  as  applied  to  the  microscope. 
During  these  years,  however,  immense  progress  has  been  made  in  this 
direction  and  there  is  a  feeling  amongst  physiologists  that  the  time  has 
•come  for  a  neAv  departure  in  histological  work  and  that  in  the  futiu^e 
the  histologist  Avill  call  to  his  aid  those  magnificent  instruments  and 
lenses  and  methods  of  work  which  have  hitherto  received  attention 
chiefly  from  those  interested  in  the  mere  optical  properties  of  lenses  or 
in  the  resolving  of  the  fine  lines  on  the  valve  of  a  diatom.  Just  as  the 
astronomer  in  a  great  observatory  requires  all  the  aid  of  the  finest 


THE  MICROSCOPE.  25.5 

telescopes,  the  most  complete  mechanical  adjustments,  the  application 
of  the  spectroscope  and  of  photography  to  enable  him  to  resolve  nebulae- 
into  star  clusters,  so  the  histologist  of  the  future,  by  applying  the  best 
methods  and  using  the  best  instruments,  hopes  to  detect  details  of 
minute  structure  in  organic  bodies  which  have  hitherto  been  described 
as  structureless  or  as  consisting  merely  of  granular  or  jelly-like  matter. 
Nor  is  this  a  mere  dream.  Already  in  these  last  few  years,  by  the 
labours  of  Flemming,  Klein,  Van  Beneden,  Carnoy,  and  many  others,  a 
new  development  has  been  given  to  our  views  of  cell  structure,  of  cell 
division,  and  of  fecundation,  by  the  use  of  high  powers  and  elaborate 
mechanical  and  chemical  methods.  Nor  need  this  view  of  the  matter 
interfere  Avith  the  appreciation  of  simple  microscopes  and  comparatively 
low  powers  for  ordinary  Avork.  It  is  quite  true  that  the  great  majority 
of  histological  facts  has  been  observed  AAdth  the  aid  of  such  instruments, 
and  that  for  ordinary  purposes  such  instruments  are  of  the  greatest  ser- 
vice, but  Ave  must  not  forget  that  these  simpler  instruments  Avith  Ioav 
poAvers  bear  the  same  relation  to  the  more  complex  instruments,  fitted 
Avith  immersion  lenses  and  achromatic  illuminating  condensers,  that  an 
ordinary  field  glass  does  to  the  best  kind  of  astronomical  telescope  in  an 
observatory,  and  that  for  many  iuA'estigations  the  finer  instrument  in 
both  cases  is  absolutely  necessary. 

1.  The  Microscope. — The  form  of  microscope  most  convenient 
for  ordinary  histological  Avork  is  such  as  is  represented  in  Fig.  123.  It 
should  be  provided  Avith  two  objectives  (Nos.  3  and  7)  and  two  eye- 
pieces (1  and  2).-^  This  will  give  a  magnifying  poAver  of  from  25  to 
350  diameters.  A  section  of  an  ocular  or  eyepiece  is  shown  in  Fig.  121, 
and  a  section  of  an  objective  in  Fig.  122.  The  larger  form  of  micro- 
scope as  made  by  Zeiss,  of  Jena,  and  shoAATi  in  Fig.  124,  is  necessary  for 
more  refined  Avork,  and  especially  for  bacteriological  investigations. 
Such  a  microscope  is  supplied  Avith  an  Abl^e's  condenser,  placed  under- 
neath the  stage,  by  which  strong  illumination  may  be  obtained.  This 
important  adjunct  to  the  microscope  is  shown  in  Fig.  125,  and  in  section 
in  Fig.  126. 

If  high  powers,  ranging  from  350  to  1000  diameters,  are  required, 
preference  should  be  given  to  homogeneous  oil  immersion  lenses,  having 
a  large  angle  of  aperture.^ 

^  The  cost  of  such  a  microscope  is  £5  10s. 

2  A  large  microscope,  similar  to  that  shoAvn  iia  Fig.  124,  with  Abbe's  condenser, 
objectives,  Nos.  4  and  7a  ;  eyepieces,  Nos.  3  and  4  ;  and  a  yV-inch  homogeneous 
oil  immersion  lens  can  be  had  from  Reichert,  of  Vienna,  for  about  £21 . 


254. 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


!•  J  epiece. 


Diawtube. 


Fig.  121.— Section  of  Hu.v- 
gbeiiian  Eyepiece  or  Ocu- 
lar. A,  eyeglass ;  B, 
field  glass;  C,  diaphragm. 


FiG.1'22. — Section  of  Ob- 
jective containing  three 
•compound  achromatic 
lenses,  each  foi-med  of 
a  double  convex  lens  of 
crown  glass,  cemented 
by  Canada  balsam  to  a 
]iiano-concave  lens  of 
flint  glass. 


Fig.  123.— Leitz's  Microscope,  No.  III.     Half  natural  size. 


THE  MICROSCOPE. 


255 


Pig.  124.— Zeiss'  Microscope,  Stand  V.a,  with  Abbe's  Condenser  below  the 
stage.     Two  thirds  natural  size. 


25G 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


Fig.  125.— Abbe's  Condenser,  as  maile  by  Zeiss;  Sii, 
mirror;  B,  brass  framework  containinglen&es,  as  shown 
in  the  next  figure  ;  g,  for  rotating  the  diaphragm, 
placed  at  r  ;  z,  movement  by  which  the  frame  beaiing 
the  diaphragm  can  be  pulled  out  from  below  the  con- 
densing lens,  S. 


Numerical  aperture  =  1'20 


Numerical  aperture  —  ViO. 

Fig.  126.— Section  of  Abbe's  Con- 
denser. (See  description  of  pre- 
vious figure.) 


METHODS  OF  MICROSCOPICAL  RESEARCH.  2bl 

It  is  essential  to  the  maintenance  of  the  good  condition  of  the 
microscope  that  it  should  be  protected  from  dust  when  frequently 
employed,  and  it  is  best  to  preserve  it  under  a  bell  glass  in  a  place  not 
exposed  to  the  rays  of  the  sun.^  The  dust,  etc.,  which  accumulates  on 
the  tube  can  be  wiped  away  with  a  small  dry  piece  of  soft  filter  paper : 
impurities  of  the  lenses  '^  and  of  the  mirror  are  to  be  removed  with  soft 
leather,  and  if  this  fails  to  attain  the  end  in  view  (as,  for  instance,  in 
the  case  of  soiling  with  Dammar  varnish),  a  small  soft  linen  duster, 
moistened  with  a  drop  of  pure  alcohol,  may  be  employed.  In  the 
process  last  mentioned,  one  must  be  very  careful  that  the  spirit  of  "vvine 
does  not  in  any  way  penetrate  into  the  setting  of  the  lenses  and  dis- 
solve the  Canada  balsam,  "with  which  they  are  fixed  in  their  places. 
Rub  off  the  stain  quickly  with  the  moistened  part  of  the  cluster,  and 
then  carefully  dry  the  lens.  The  screws  of  the  microscope  should  be 
cleaned  with  petroleum.  Take  particular  care  of  the  fine  adjustment 
screw.  This  should  never  be  screwed  either  too  far  up  or  too  far  down, 
and  it  should  only  be  employed  for  delicate  focusing,  never  for  finding 
the  object. 

Mode  of  Using  the  Microscope. — The  first  condition  is  the  complete  clear- 
ness of  the  various  lenses.  The  mirror,  objectives,  and  eyepieces  must 
not  be  touched  on  their  upper  surface  with  the  fingers.  Hold  the  object- 
glasses  by  the  under  end  up  against  the  window  and  test  the  clearness 
of  the  reflected  image.  The  screwing  on  to  the  tube  is  effected  by 
holding  the  objective  fast  and  turning  the  tube  round.  The  eyepiece 
is  then  inserted  ;  impurities  on  it  can  be  recognized  by  turning  it  round 
in  the  tube ;  if  any  impurity  adheres  to  the  eyepiece,  it  revolves  along 
with  it. 

Now  find  light.  To  do  so,  draw  the  body  of  the  microscope  out  of 
the  draw  tube  for  a  distance  of  about  half  an  inch,  look  through  the 
microscope  towards  the  opening  in  the  diaphragm  and  move  the  mirror 
until  the  light  is  reflected  upwards.  The  rays  of  light  reflected  from 
the  mirror  so  placed  strike  the  object  vertically.  This  mode  of  illumin- 
ation is  termed  centred  illumination. 

1  In  the  preparation  of  tlie  portion  of  this  chapter  dealing  with  the  microscope 
and  with  histological  methods,  I  have  largely  availed  myself  of  Professor  Stohr's 
directions  in  his  work,  Lehrhucli  der  Bistologie,  and  with  the  greater  confidence, 
as  the  methods  therein  described  are  substantially  those  followed  in  the  laboratory 
of  the  University  of  Glasgow,  in  teaching  practical  histology.  I  purchased  the 
right  of  translation  of  this  work  from  the  publisher,  Gustav  Fischer,  of  Jena, 
with  Professor  Stohr's  consent. 

2  The  lenses  of  the  objective  must  never  be  screwed  from  each  other. 

I.  R 


258  THE  PHYSIOLOGY  OF  THE  TISSUES. 

Ill  order  to  recognize  finer  differences  of  surface,  we  may  advanta- 
geously employ  the  ohliqne  or  lateral  illumination,  in  Avhich  the  mirror  is 
pushed  on  its  side  in  such  a  manner  that  the  rays  of  light  reflected  from  it 
fell  ol)lic|uely  on  the  object.  As  sources  of  light,  a  white  cloud  illumined 
by  the  sun,  or  white  curtains  on  which  the  sun  shines,  are  to  be  chosen  ; 
less  good,  but  still  serviceable,  is  the  blue  sky ;  direct  sunlight  must  be 
avoided.  If  in  the  evening  we  work  with  artificial  light,  we  m\tst 
derive  the  light  from  the  inner  surface  of  a  lamp  shade,  not  directly 
from  the  flame.  A  green  plate  of  glass,  placed  before  the  mirror,  tones 
down  the  artificial  light  without  essentially  injuring  the  distinctness  of 
the  images.  It  is  self-evident  that  the  investigator  with  the  microscope 
should  not  sit  in  the  sunshine ;  he  should  place  the  microscope  at  a 
distance  of  aliout  two  metres  from  the  window. 

The  investigation  may  noAv  begin.  Always  investigate,  first  of  all, 
with  tveak,  and  then  uith  strong  magnifying  powers,  and  he  very  specially 
warned  against  the  use  of  strong  ocidars.  The  weakest  oculars  given  with 
the  usual  microscopes  (and  even  the  medium  ocular,  Oc.  1  of 
Leitz)  are  adequate  for  the  majority  of  cases  :  too  strong  oculars  lessen 
and  darken  the  field  of  vision,  and  render  the  investigation  difficult 
in  a  high  degree.  Also  the  drawing  out  of  the  tube  is  usually 
unnecessary.  When  using  low  powers,  have 
the  largest  aperture  of  the  diaphragm  under 
the  opening  in  the  stage;  and  when  using 
high  magnifying  powers,  have  the  smallest 
aperture  in  this  position.  For  ordinary 
objectives  (No.  3  and  No.  7),  the  concave 
mirror  is  to  be  used.  In  finding  the  object, 
do  not  force  the  tube  straight  down,  but 
lower  it  by  revolving  it  spirally  until  the 
^     ,„_    ^.    ,  object  on  the  staa:e  comes  indistinctly  into 

Fig.  12i. — Diaphragm.  •>  o  J  _ 

view.  Then  use  the  fine  adjustment  until 
complete  distinctness  of  the  object  has  been  attained.  Thereupon  let 
the  left  hand  hold  the  slide,  and  the  right  hand  rest  on  the  micrometer 
screw.  As  Ave  see  clearly  only  the  points  of  the  preparation  lying  in 
one  plane,  scrutinize  the  preparation  during  the  delicate  raising  and 
lowering  of  the  tube,  i.e.  during  the  slow  turning  of  the  micrometer 
screw.  In  addition  to  this,  keep  both  eyes  open  during  microscopic 
investigation. 

The  delineation  or  sketching  of  microscopic  objects  is  an  invaluable 
aid  to  correct  observation.  Thus  many  details  are  shown  which  might 
otherwise  have  been  completely  overlooked.  Even  the  most  attentive 
contemplation  cannot  supply  the  advantages  which  drawing  the  objects 


METHODS  OF  MICROSCOPICAL  RESEARCH. 


259 


commands.  Endeavour  also  to  sketch  objects  seen  by  low  and  high 
powers.  In  drawing,  place  the  paper  on  the  level  of  the  stage,  look 
into  the  microscope  with  the  left  eye,  and  with  the  right  look  on  the 
paper  and  the  point  of  the  lead  pencil.  At  first  this  occasions  a  little 
■difficulty  ;  after  some  practice  we  rapidly  acquire  the  necessary 
dexterity.  When  it  is  necessary  to  make  an  exact  facsimile  drawing 
of  an  object,  a  camera  htcida  should  be  used,  of  which  by  far  the  most 
■convenient  is  that  shown  in  Fig.  128. 


Fig.  128. — Abbe's  Camera  Lucida,  made  by  Zeiss.  A,  Part  screwed  over  the  eyepiece. 
B,  Mirror,  reflecting  light,  coming  from  paper  in  direction  S^ ,  at  right  angles  in  direction 
Sp —  IF.  This  light  is  caught  by  the  prism  and  reflected  in  direction  of  0,  the  same  direc- 
tion as  that  followed  by  the  rays  coming  from  the  object  in  the  direction  AO. 


2.  Accessory  Appliances.- 

sites  for  histological  work — 


-The  following  are  convenient  requi- 


(1)  A  good  razor,  the  blade  of  which  has  been  flattened  on  one  side.  The 
iblade  must  always  be  kept  sharp  and  must,  previous  to  actual  use,  be  passed 
over  the  strop.  Let  the  razor  be  employed  exclusively  for  the  cutting  of  fine 
sections. 

(2)  A  fine  ivhetdone. 

(3)  A  neat  straight  2iciir  of  scissors. 

(■4)  A  delicate,  easily  shutting  pair  of  forceps,  with  smooth  or  only  slightly 
indented  prongs. 

(5)  Four  needles  with  wooden  handles.  Let  two  of  them  be  heated  until  they 
•can  easily  be  bent ;  let  them  be  again  heated,  and  then  stuck  into  solid  paraffin, 
by  which  they  will  again  be  hardened.  In  fine  teazing,  the  needles  must  be 
sharpened  and  polished  first  on  the  whetstone,  and  then  on  the  strop.  The 
cataract  needles  of  oculists  are  very  useful. 

(6)  A  flat  spatida,  made  of  German  silver,  for  lifting  the  sections  from  fluids  on 
ito  the  slide.  Instead  of  this,  a  broad-bladed  knife  may  be  used.  One  of  those  in 
&  case  of  anatomical  instruments  suits  quite  well. 

(7)  Pins,  hedge-hog  bristles,  a  small  paint  brush,  a  brush  for  dusting  glasses. 

(8)  Slides  (of  the  usual  shape)  should  be  made  of  pure  glass,  and  not  too  thick 
((1-1  "5  mm.). 

(9)  Cover-glasses  of  15  mm.  broad  are  for  most  objects  sufficiently  broad  ;  their 
thickness  may  vary  from  O'l  to  0"2  mm. 


260  THE  PHYSIO  LOG  V  OF  THE  TISSUES. 

(10)  Ghi)^s  phials  to  the  number  of  a  dozen,  with  a  wide  neck,  of  the  capacity  of 
30  c.c.  and  upwards. 

(11)  Some  lar(jir  preparation  (jlasxi'^,  with  ground-glass  stoppers;  height,  7-10 
cm.  ;  diameter,  6-10  cm. 

(12)  A  graduated  cylindrical  glaK-t,  holding  100-150  com. 

(13)  A  glass  funnel  of  8-10  cm.  at  its  upper  diameter. 

(14)  Pipette.  The  student  can  supply  himself  with  pipettes  if  he  draws  off  to- 
a  lioint  at  one  end,  in  the  blow-pipe  flame,  a  small  glass  tube  about  1  cm.  in  diameter 
and  10  cm.  in  lengtli,  and  fixes  on  the  other  end  a  piece  of  india-rubber  tubing,  ft 
cm.  long,  tied  with  a  strong  packthread. 

(15)  One  dozen  vatch  glasses  of  5  cm.  in  diameter. 

(16)  One  dozen,  small  reagent  glasse.i  of  the  capacity  of  10  cm.  in  length,  and  of 
12  mm.  in  width. 

(17)  Glass  rodx  of  3  mm.  thick,  15  cm.  long,  drawn  to  a  point  at  one  end. 

(18)  Preparation  dishes  with  glass  lids  of  10-12  cm.  in  diameter. 

(19)  Txco  sheets  of  blotting  paper,  a  cork  plate,  large  and  s7naU  gummed  carder 
soft  linen  rags,  a  toirel. 

(20)  A  large  earthenware  pot  for  refuse. 

3.  Reagents. — It  is  not  advisable  to  keep  reagents  in  store  in  too- 
great  qnantities,  for  many  of  them  become  decomposed  in  a  compara- 
tivel)'  short  time.  Reagents  must  be  i)rocured  shortly  before  use. 
Every  flask  must  be  provided  with  a  large  label  indicating  its  contents. 
It  is  recommended  that  not  only  should  the  prescription  of  the  parti- 
cular fluid  be  indicated  on  the  label,  but  also  the  method  of  employing 
it.  All  the  flasks  should  be  closed  tightly  with  corks  or  with  good 
glass  stoppers.  The  fluid  must  not  reach  to  the  under  surface  of 
the  cork. 

( 1 )  Distilled  water,  3-6  litres. 

(2)  Solution  of  common  salt,  0'75  per  cent.  :  distilled  water,  200  c.cm.  ;  common 
salt,  1  "5  grms.  The  coi'k  of  the  flask  must  be  provided  with  a  glass  rod  reaching 
down  to  the  bottom  of  the  Hask.  The  liquid  decomposes  readily,  and  must  be 
frequently  prepared  anew. 

(3)  Alcohol — (a)  Absolute  alcohol.  Of  this,  it  is  necessary  to  have  200  c.cm.  in,- 
readiness.  The  absolute  alcohol  of  commerce  is  of  the  strength  of  96  per  cent., 
and  it  is,  in  the  majority  of  cases,  at  ouce  available  for  microscopic  purposes.  If,. 
however,  anyone  wishes  to  preserve  in  alcohol  completely  free  of  water,  he  must 
throw  into  the  flask  some  small  pieces  (15  grms.  to  100  c.cm.  of  alcohol)  of  dried 
sulphate  of  copper  (CUSO4)  that  has  been  heated  to  a  white  heat.  In  the  event 
of  its  turning  blue,  it  must  either  give  j)lace  to  a  fresh  supply,  or  be  burned  anew. 
Newly  burnt  chalk  likewise  serves  a  like  purpose,  only  its  operation  is  more  pro- 
tracted, (b)  Pure  spirit  (strength,  90  per  cent,  of  alcohol),  3-5  litres ;  may  be  called 
90  per  cent,  alcohol,  (c)  70  per  cent,  alcohol.  500  c.cm.  are  to  be  made  by  the 
mixture  of  390  c.cm.  of  90  per  cent,  alcohol  with  110  c.cm.  of  distilled  water. 
(d)  Ranvier's  third-part  alcohol,  or,  shortly,  Ranvier's  alcohol.  45  c.cm.  of  90  per 
cent,  alcohol  +  85  c.cm.  of  distilled  water. 

(4)  Acetic  acid,,  50  c.cm.     The  kind  used  by  chemists  is  33  per  cent,  strong. 


METHODS  OF  MICROSCOPICAL  RESEARCH.  2G1 

(o)  Acetate  of  iron  (that  purchasable  in  chemists'  shops  is  96  per  cent,  strong) 
must  be  inspected  shortly  before  use  (amount,  10  c.cm.). 

(G)  Nitric  acid.  It  is  necessary  to  possess  a  iiask  containing  100  c.cm.  of  con- 
centrated nitric  acid  of  specific  gravity,  1"18. 

(7)  Pure  hydrochloric  acid,  50  c.cm. 

(8)  Chromic  acid.  Make  a  10  per  cent,  solution  (10  grms.  of  newly  procured 
•crystallized  chromic  acid  to  be  dissolved  in  90  c.cm.  of  distilled  water).  Of  this, 
make  (a)  a  solution  of  chromic  acid,  '1  per  cent.  (10  c.cm.  of  the  strong  solution  to 
390  c.cm.  of  distilled  water),  and  (b)  a  "5  per  cent,  solution  of  chromic  acid  (50 
c.cm,  of  the  first  solution  to  950  c.cm.  of  distilled  water). 

(9)  Bichromate  ofjyotash.  Dissolve  25  grms.  in  1,000  c.cm.  of  distilled  water.  It 
dissolves  slowly  (from  three  to  six  days). 

(10)  Midler's  fluid,  30  grms.  of  sulphate  of  soda  and  60  grms.  of  pulverized 
bichromate  of  potash  are  dissolved  in  3,000  c.cm.  of  distilled  water.  The  solution  is 
effected  slowly  at  the  ordinary  temperature  of  a  room  (from  three  to  six  days), 

(11)  Picric  acid.  Keep  50  grms.  of  crystals,  and  also  a  saturated  aqueous  solution 
<500  c.cm).  The  crystals  must  always  be  in  a  layer,  from  2  to  3  mm.  in  depth,  at 
the  bottom  of  the  flask.     It  dissolves  easily. 

(12)  Sulpho-picric  acid  (Kleinenbei-g).  Into  200  c.cm.  of  satvirated  solution 
of  picric  acid,  pour  4  c.cm.  of  pure  sulphuric  acid  ;  a  dense  precipitate  im- 
mediately forms.  After  the  lapse  of  an  hour,  this  mixture  is  filtered,  and  the 
filtrate  is  diluted  with  600  c.cm.  of  distilled  water.  The  residuum  left  behind  in 
the  filter  is  to  be  thrown  away. 

(13)  Osmic  acid.  Purchase  50  c.cm.  of  2  per  cent,  aqueous  solution.  It  must  be 
kept  in  a  dark  place  or  in  a  dark  glass,  and,  when  well  closed  up,  it  keeps  for 
many  months. 

(14)  Chromo-osmium  acetic  acid.  Prepare  a  solution  of  chromic  acid,  1  per 
cent,  strong  (5  c.cm.  of  a  10  per  cent,  solution  to  45  c.cm.  of  distilled  water), 
and  pour  into  it  12  c.cm.  of  2  per  cent,  solution  of  osmic  acid,  and  add  to  it  3  c.cm, 
of  acetic  acid.  This  mixture  need  not  be  kept  in  the  dark,  and  is  available  for 
use  for  a  long  time. 

(15)  Nitrate  of  silver.  Procure,  a  short  time  previous  to  using  it,  a  solution  of 
nitrate  of  silver,  1  grm.  in  100  c.cm.  of  distilled  water.  The  fluid  must  be  kept 
in  the  dark  or  in  a  black  bottle.     It  keeps  for  a  long  time. 

(16)  Chloride  of  gold.  Procure  shortly  before  use  a  solution  of  1  grm.  of 
■chloride  of  gold  in  100  c.cm.  of  distilled  water.  Must  be  kept  in  the  dark  or  in 
a  black  or  dark  brown  flask, 

(17)  Formic  acid,  50  c.cm.,  for  chloride  of  gold  staining. 

(18)  Concentrated  (35  per  cent.)  caustic  potash,  30  c.cm.  The  bottle  must  be 
•closed  with  an  unvulcanized  India-rubber  stopper  which  is  penetrated  by  a  glass  rod. 

(19)  Glycerine.  It  is  necessary  to  have  at  hand  100  c.cm.  of  pure  glycerine,  as 
well  as  a  solution  of  5  c.cm.  of  pure  glycerine  in  25  c.cm.  of  distilled  water.  As  a 
safeguard  against  fungi,  which  speedily  appear  in  this  mixture,  there  may  be 
added  to  it  5  to  10  drops  of  a  pure  1  per  cent,  solution  of  carbolic  acid.  The  cork 
of  the  bottle  must  be  provided  with  a  glass  rod,  as  also  in  the  case  of — 

(20)  Lavender  oil,  20  c.cm.     Oil  of  cloves  serves  the  same  purpose. 

(21)  Dammar  varnish.  It  can  be  bought  in  bottles,  containing  50  c.cm.,  from 
drysalters,  and,  when  too  viscid,  be  diluted  with  pure  oil  of  turpentine.  It 
possesses  the  requisite  degree  of  consistency  when,  if  a  glass  rod  be  dipped 
in  it,    the  drops  fall  off  without   dragging  long  threads  after  them.     Dammar 


262  THE  PHYSIOLOGY  OF  THE  TISSUES. 

varnish  is  to  be  preferred  to  the  too  strongly  refractive  Canada  balsam  (which 
is  diluted  with  chloroform),  but  it  possesses  the  drawback  of  drying  very 
slowly,  while  Canada  balsam  dries  quickly.  The  cork  of  the  flask  must  be  pro- 
vided with  a  glass  rod. 

(22)  Cemant  for  corer-r/last.  Venetian  turpentine  may  be  diluted  with  sulphuric- 
ether  until  the  whole  forms  a  fluid  trickling  easily  in  drops  ;  next  it  is  filtered 
while  hot  in  a  funnel  surrounded  by  hot  water,  and  the  filtrate  is  thickened  on 
the  sandbath.  The  proper  consistence  has  been  attained  when  a  drop  of  it  placed 
by  a  glass  rod  on  a  slide  immediately  becomes  stiffened  to  such  an  extent  that  it 
can  no  longer  be  compressed  by  the  finger  nail.  It  may  be  prepared  in  a  chemist's- 
as  a  safeguard  against  danger  from  burning.  Zinc-ivhite  is  also  an  excellent  cement. 
A.^phalt-varjiish  cannot  be  recommended. 

(23)  Hcemafoxi/Un.  (1)  1  grm.  of  crystallized  hamatoxylm  is  dissolved  in  10 
c.cm.  of  absolute  alcohol.  (2)  20  grms.  of  alum  are  dissolved  in  200  c.cm.  of  dis- 
tilled water,  when  warm,  and  filtered  after  cooling.  On  the  following  day,  both 
solutions  are  mixed,  and  they  are  allowed  to  stand  for  eight  days  in  a  wide- 
mouthed  vessel.  The  mixture  is  then  filtered,^  and  is  ready  for  use.  Diminution 
of  transparency  from  development  of  fungi  does  not  in  the  least  injure  its  useful- 
ness. 

(24)  Weigert's  Juemafoxy/ht,  for  the  demonstration  of  medullated  nerve  fibres  of 
the  brain  and  spinal  marrow.  1  grm.  of  crystallized  htematoxylin  is  placed  in  10 
c.cm.  of  absolute  alcohol  +  90  c.cm.  of  distilled  water,  and  then  boiled.  After 
cooling,  there  is  added  to  it  1  to  2  c.cm.  of  a  solution — saturated  when  cold — of 
carbonate  of  lithium.  The  employment  of  this  reagent  demands  previous  treatment 
with  (o)  Saturated  solution  of  neutral  acetate  of  copper,  300  c.cm.,  and  a  subsequent- 
treatment  with  a  {!))  Solution  of  ferridcyanide  of  jjotasdum  aiul  ofhorax.  2  grms. 
borax  and  2i  grms.  of  ferridcyanide  of  potassium  are  dissolved  in  100  c.cm.  of 
distilled  water. 

(25)  Neutral  solution  of  carmine.  1  grm.  of  the  best  carmine  is  dissolved  cold 
in  50  c.cm.  of  distilled  water  +  5  c.cm.  liquor  ammonite.  The  brilliant  cherry-red 
fluid  remains  exposed  until  it  no  longer  yields  an  odour  of  ammonia  (two  days)  and 
it  is  then  filtered.  To  be  kept  ready  at  hand.  The  odour  of  this  solution  may 
become  very  off'ensive,  but  its  colouring  power  is  not  thereby  injured. 

(26)  Picrocarmine.  Pour  into  50  c.cm.  of  distilled  water  5  c.cm.  of  liquor 
ammoniffi,  and  throw  into  this  mixture  1  grm.  of  the  best  carmine.  Stir  round 
with  a  glass  rod.  After  the  solution  of  the  carmine  has  been  completed  (in 
about  five  minutes),  pour  into  it  50  c.cm.  of  a  saturated  solution  of  picric  acid,  and 
then  let  the  whole  stand  for  two  days  in  a  wide-mouthed  vessel.  Then  filter  it. 
Even  abundant  development  of  fungi  does  not  injure  the  colouring  power  of  this- 
excellent  reagent. 

(27)  Borax  carmine.  4  grms.  of  borax  are  dissolved  in  100  c.cm.  of  warm  dis- 
tilled water.  After  the  solution  has  cooled,  3  grms.  of  good  caiunine  are  added 
during  stirring,  and  then  100  c.cm.  of  70  per  cent,  alcohol  are  poured  in.  After  the 
lapse  of  twenty -four  hours,  filter  the  fluid,  which  drops  very  slowly,  taking  twenty- 
four  hours  and  even  longer  in  passing  through  the  filter.  The  staining  by  borax  car- 
mine demands  siibsequent  treatment  with  70  per  cent,  hydrochloric-acid-alcohol,. 

1  After  the  cooling  of  the  alum,  as  well  as  after  the  haematoxylin-alum  mixture 
has  stood  exposed  for  eight  days,  there  are  found  (especially  at  a  lower  temperature ) 
alum  crystals  at  the  bottom  of  the  vessel,  which  are  not  of  further  use. 


METHODS  OF  MICROSCOPICAL  RESEARCH.  263 

which  is  prepared  by  means  of  the  addition  of  4  to  6  drops  of  pure  hydrochloric  acid 
to  100  c.cm.  of  70  per  cent,  alcohol. 

(28)  Safranin.  2  grms.  of  the  dye  are  to  be  dissolved  in  60  c.cm.  of  50  per 
cent,  alcohol  (33  c.cm.  of  90  per  cent,  alcohol  +  27  c.cm.  of  distilled  water). 
Staining  with  safFranin  requires  subsequent  treatment  with  absolute  hydrochloric- 
acid-alcohol  (8  to  10  drops  of  pure  hydrochloric  acid  to  100  c.cm.  of  absolute  alcohol). 
Both  may  be  kept  in  readiness. 

(29)  Eosin.  1  grm.  of  the  dye  to  be  dissolved  in  60  c.cm.  of  50  per  cent, 
alcohol  (33  c.cm.  of  90  per  cent,  alcohol  +  27  c.cm.  of  distilled  water). 

(30)  Vesuvin,  or 

(31)  Methyl- violet,  B.,  may  be  kept  in  readiness  in  saturated  watery  solu- 
tions (1  grm.  to  50  c.cm.  of  distilled  water). 

4.  Preparation  of  Tissues  and  Organs. — The  minutest  organs 
of  the  animal  frame  are  so  constituted  that  they  are  immediately  access- 
ible to  microscopical  investigation.  They  must  possess  a  certain  degree 
of  transparency,  which  we  effect  either  by  dividing  the  organs  into  small 
portions — isolating  the  elements,  or  by  cutting  them  into  sections — 
dissecting  them.  But  on  the  other  hand  the  minutest  organs  may  not 
possess  a  consistency  Avhich  permits  the  immediate  prejmration  of  fine 
sections.  They  may  be  too  soft  (in  which  case  they  must  be  hardened), 
or  too  hard,  from  the  presence  of  earthy  matter  (in  which  case  they  must 
be  decalcified).  As  hardening  and  decalcification  cannot  be  exercised  on 
objects  which  are  fresh  without  injuring  their  structure,  both  methods 
must  be  preceded  by  a  process  which  renders  possible  a  rapid  harden- 
ing or  stiff"ening  and  also  a  permanent  hardening  of  the  minutest 
particles.  This  process  is  termed  fixing.  The  preparation  of  fine 
sections  is  accordingly  possible,  only  after  the  previous  fixing  and 
hardening  of  the  objects  concerned  (decalcification  eventually  following). 
But  the  sections  also  demand  further  manipulation.  They  may  either 
be  made  transparent  immediately  by  means  of  appliances  for  rendering- 
objects  clear  (which  are  even  applied  with  success  to  fresh  objects),  or 
they  m.ay  be  coloured  or  stained  before  clearing.  Colouring  matters 
furnish  invaluable  aids  to  microscopic  research,  as  they  admit  of  appli- 
cation to  fresh,  and  even  to  living,  organs.  A  great  number  of  the  most 
important  facts  have  been  discovered  only  by  means  of  their  helj). 
Colouring  matters  syringed  into  vessels  (injected)  show  their  mode  of 
division  and  the  course  of  the  finest  ramifications  of  the  capillaries. 

1.  Nature  of  the  Material. — For  studies  of  the  elements  of  form  and 
of  the  so-called  "simple  tissues,"  we  recommend  amj^hibia,  such  as 
frogs  and  salamanders  (the  spotted  salamander,  whose  elements  are 
very  large,  being  the  best).  On  the  other  hand,  the  mammalia  are  re- 
commended for  the  studies  of  the  organs.  In  many  cases  rodentia 
suffice  (rabbit,  guinea-pig,   rat,  mouse),   or  the  tissues  and   organs  of 


264  THE  rilY^WLOLlY  OF  THE  TISSUES. 

young  clogs,  cats,  etc.,  may  be  employed.  Nevertheless  no  one  should 
neglect  any  opportunity  of  acquiring  the  organs  of  the  human  sub- 
ject.    Fresh  material  may  be  obtained  from  the  surgical  clinic. 

In  general,  it  is  advisable  to  collect  the  organs  before  the  vital 
heat  has  departed.  In  order  to  do  this  Avith  the  utmost  possible 
despatch,  it  is  recommended  to  fill,  first  of  all,  with  the  suitable 
tiuid,  the  jars  selected  for  the  reception  of  the  objects,  and  to  pro- 
vide labels  indicating,  along  Avith  the  object,  the  name  of  the  fluid  and 
the  date.  In  the  next  place,  let  the  instruments  for  dissection  be 
arranged,  and  not  until  then  should  the  animal  be  killed. 

2.  Killinfj  and  Disscdion  of  Animals. — In  the  case  of  amphibia, 
the  operator  should,  with  a  strong  pair  of  scissors,  sever  the  verte- 
l)ral  column  at  the  neck,  and  destroy  the  brain  and  the  spinal  marrow 
by  means  of  a  needle  thrust  from  the  wound  upwards  into  the  cavity 
of  the  skull,  and  downwards  into  the  vertebral  canal.  In  the  case  of 
mammals,  the  operator  should  cut  through  the  neck  Avith  a  vigorous 
incision  reaching  to  the  vertebral  column,  or  he  may  kill  them  with 
chloroform,  which  is  poured  upon  a  cloth  and  pressed  against  the  noses 
of  the  animals.  Small  animals  (4  cm.  large),  or  embryos,  may  be 
thrown  entire  into  the  fixing  fluid.  After  the  lapse  of  six  hours, 
open  the  abdomen  and  thorax  hj  incisions.  It  is  easy  with  a 
strong  pin  to  fix  the  bodies  of  small  animals  by  the  sole  of  the 
foot  on  to  plates  of  cork  or  wax.  The  organs  must  be  neatly  removed, 
best  with  forceps  and  scissors ;  squeezing  and  pressing  of  the  parts, 
and  taking  hold  of  them  by  the  fingers,  are  to  be  altogether  avoided. 
The  forceps  should  grasp  the  edge  only  of  the  object.  Adhering  im- 
purities— mucus,  blood,  and  the  contents  of  the  intestines— must  not  be 
scraped  off"  with  the  scalpel,  but  must  be  removed  by  slowly  swinging 
the  part  in  the  fixation-fluid  used  in  the  process. 

By  the  methods  specitied  in  the  sequel,  it  is  unavoidable  that  scissors,  forceps, 
needles,  glass  rods,  etc.,  should  be  -wetted  by  the  most  diverse  kinds  of  fluids — 
with  acids  for  example.  The  instruments  should  be  cleaned  immediately  after 
use  by  being  rinsed  in  water,  and  wiped  dry.  The  operator  should  avoid 
above  everything  dipping  into  another  fluid  a  glass  rod  soiled,  for  example, 
with  an  acid  or  with  a  colouring  material.  Overlooking  this  circumstance  often 
leads  to  the  reagents  being  decomposed,  or  it  may  entirely  nullify  the  success  of 
the  subsequent  preparations.  Glasses,  watch  glasses,  etc.,  are  easily  cleaned 
when  it  is  done  immediately  after  use.  If,  on  the  other  hand,  the  operator 
allows,  for  example,  the  residuum  of  a  colouring  material  to  dry  up  in  a  glass,  the 
cleaning  of  the  latter  always  entails  a  tedious  consumption  of  time.  The  operator 
should  never  neglect  to  clean  glasses  immediately  after  use ;  watch  glasses 
at  least  may  be  throwTi  into  a  vessel  of  water.  All  vessels  in  which  the  operator 
isolates,  fixes,  hardens,  colours,  etc.,  must  be  kept  close  (watch  glasses  may  be 


METHODS  OF  MICROSCOPICAL  RESEARCH.  265 

covered  with  a  second  -watch  glass  if  the  duration  of  the  manipulations  lasts  more 
than  ten  minutes),  and  should  not  be  exposed  to  the  sun. 

3.  Isolation. — We  isolate  either  by  teazing  fresh  objects,  or  by 
teazing,  after  previous  treatment  of  objects  with  fluids  which  dissolve 
some  elements  of  the  tissue.  Sometimes  such  fluids  render  teaz- 
ing altogether  or  partially  unnecessary.  It  is  a  difficult  under- 
taking to  make  a  good  preparation  by  teazing.  Much  patience 
and  scrupulous  fulfilment  of  the  following  directions  are  indis- 
pensable. The  needles  must  be  sharp  at  the  point  and  quite 
clean;  previous  to  use,  they  should  be  sharpened  and  polished  on  the 
moistened  whetstone.  The  small  object  (at  most  5  mm.  broad)  is  now 
l^laced  in  one  small  drop  upon  the  slide,  and,  if  it  is  coloiu:'less,  torn 
asunder  on  a  black  background,  but  if  it  is  dark  (coloured  somewhat) 
the  operation  is  performed  on  a  white  background.  If  the  object  is 
fibrous  {e.g.  a  bundle  of  muscular  fibres),  the  operator  should  place  both 
needles  on  the  one  end  of  the  bundle,  and  teaze,  in  the  direction  of  its 
length,  into  two  bundles  ;  one  of  these  bundles  is  in  the  same 
way  divided  in  turn  into  two  bundles  by  means  of  placing  the 
needles  on  the  end,  and  so  on,  until  very  fine  single  fibres  are  reached. 
By  observation  of  the  (uncovered)  ^preparation  with  a  low  magnifying 
IDOwer,  we  can  ascertain  whether  the  necessary  degree  of  fineness  has 
been  reached.     As  isolating  fluids  there  are  to  be  recommended — 

(a.)  For  Eplthdia.  Ranvier's  alcohol  is  a  useful  fluid  for  isolation.  Place 
sideways  into  10  com.  of  this  fluid  a  small  piece,  say  of  the  mucous  mem- 
brane of  the  intestines,  of  5  to  10  mm.  After  the  lapse  of  five  hours  (in  the  case  of 
stratified  pavement  epithelium,  after  the  lapse  of  ten  to  twenty-four  hours  or  more), 
the  small  pieces  are  cautiously  and  slowly  lifted  out  with  a  pair  of  forceps,  and  twice 
dashed  gently  against  the  slide,  which  has  been  covered  with  one  drop  of 
fluid.  In  consequence  of  the  impact,  many  epitheliimi  cells  fall  off'  isolated, 
or  in  groups,  wliich  require  only  to  be  gently  stirred  round  with  the  needle 
to  secure  complete  isolation.  Place  a  cover -glass  over  the  preparation,  and 
examine  with  the  microscope.  If  the  experimenter  wishes  to  colour  the  object, 
he  takes  the  small  pieces  en  masse  carefully  out  of  the  alcohol  and  places  them 
into  6  c.cm.  of  picrocarmine.  After  two  to  four  hours,  the  small  piece  is  placed 
very  carefully  into  5  c.cm.  of  distilled  water,  and  five  minutes  after  is  transferred 
to  a  slide  and  placed  in  a  drop  of  diluted  glycerine.  Then  put  on  the  cover-glass. 
The  preparation  may  be  preserved. 

(h)  For  Muscular  Fibres  or  Glands.  These  require  35  per  cent,  solution  of 
caustic  potash.  Small  pieces  from  10  to  20  mm.  broad  are  immersed  in  10  to  20 
c.cm.  of  this  fluid.  After  the  lapse  of  nearly  an  hour,  the  small  pieces  have  fallen 
asunder  into  their  elements,  which  are  fished  out  with  needles  or  with  a  pipette,  and 
examined  in  a  drop  of  similar  caustic  potash  under  a  cover-glass.  Diluted  caustic 
potash  operates  in  an  altogether  different  manner.  The  elements  are  soon 
destroyed  in  dilute  caustic  potash.     If  the  caustic  potash  is  too  old,  isolation 


266  THE  PHYSIOLOGY  OF  THE  TISSUES. 

does  not  succeed  ;  instead  of  it  a  pulpy  softening  of  the  small  pieces  sometimes 
occurs.  For  this  reason,  freshly-prepared  solutions  should  always  be  employed. 
Even  successful  pi'eparations  of  this  kind  cannot  be  preserved. 

There  is  further  required  a  mixture  of  chloride  of  potassium  and  of  nitric 
acid.  This  is  prepared  by  throwing  into  20  com.  of  pure  nitric  acid  such  a 
quantity  of  chloride  of  potassium  (5  grms.)  that  an  undissolved  sediment 
remains  at  the  bottom.  After  the  lapse  of  fourteen  hours  (sometimes  earlier,  often 
later),  the  object  is  sufficient!}'  loosened,  and  it  is  now  transferred  into  20  c.cm. 
of  distilled  water,  in  which  it  remains  one  hour,  although  it  may  remain  in  it 
even  eight  days  without  injury.  It  is  then  transferred  to  a  slide,  where  it  may 
with  ease  be  teazed  in  a  drop  of  dilute  glycerine.  If  the  nitric  acid  has  been  well 
washed  out,  the  preparations  admit  of  preservation,  and  even  of  being  coloiired 
under  the  cover-glass.  Placing  small  pieces  not  yet  teazed  in  picrocarmine  does 
not  succeed,  as  this  colouring  liquid  makes  objects  brittle. 

(c)  For  (he  Ducts  and  Ductlet>s  of  Glands.  Place  small  pieces  (from  1  cm.  broad) 
into  10  c.cm.  of  pure  hydrochloric  acid.  After  the  lapse  of  ten  to  twenty  hours, 
the  small  pieces  are  immersed  in  30  c.cm.  of  distilled  water,  which  must  be 
changed  several  times  within  twenty-four  hours.  The  isolation  is  then  success- 
fully accomi^lished  by  means  of  the  cautious  spreading  out  of  the  small  piece  with 
needles  in  a  drop  of  dilute  glycerine.     The  preparation  may  be  preserved. 

4.  Fixing — General  Hales. — (1)  For  fixing,  there  must  always  be  em- 
plo3'ed  a  copious  amount  of  fluid — more  than  50  to  100  times  the 
volume  of  the  object  to  be  fixed.  (2)  The  liquid  must  be  always  clear; 
it  must,  immediately  after  it  has  become  turbid,  be  changed,  i.e.  its 
place  must  be  supplied  by  fresh  fluid.  The  turbidity  often,  indeed, 
occurs  one  hour  after  immersion.  (3)  The  objects  to  be  fixed  should 
1)6  of  the  smallest  possible  size ;  they  should  in  general  not  exceed 
1  to  2  c.cm.  Should  the  preservation  of  the  entire  object  be  necessary, 
(say  for  subsequent  adjustment,  so  that  sections  may  be  cut  of  the 
complete  organ  in  its  natural  position)  make  in  it  several  deep  incisions 
five  to  ten  hours  after  the  first  immersion.  In  the  case  of  the  fixing  of 
delicate  objects,  the  experimenter  should  place  a  thin  layer  of  wadding 
(1  cm.  in  thickness)  at  the  bottom  of  the  vessel. 

1.  Ahiiolufe  alcohol  is  very  well  adapted  for  glands,  skin,  and  blood-vessels.  It 
is  used  similarly  for  hardening.  Objects  placed  in  absolute  alcohol  may  be  cut 
after  twenty -four  hours.^  On  this  account  it  is  specially  adapted  for  the  rapid 
mounting  of  preparations.  The  following  directions  must  be  observed— (I)  The 
absolute  alcohol  must  be  changed  after  three  or  four  hours,  even  if  it  is  not 
turbid  ;  (2)  the  operator  must  take  care  that  the  immersed  objects  are  not 
packed  closely  or  allowed  to  stick  fast  to  the  bottom  of  the  glass.-  On  this 
account  we  either  suspend  the  objects  in  alcohol  by  a  thread,  or  place  a  small  pad 

^  The  working  up  of  objects  fixed  in  absolute  alcohol  should  not  be  delayed 
too  long,  as  the  elements  gradually  deteriorate.  Cut  after  the  lapse  of  one  to 
eight  days. 

-  The  places  in  question,  on  being  cut,  appear  strongl}-  compressed. 


METHODS  OF  MICROSCOPICAL  RESEARCH.  267 

of  cotton  wool  at  the  bottom  of  the  glass  ;  in  many  cases  frequent  shaking  of  the 
glass  suffices. 

Alcoliol  not  absolute  (say  90  per  cent.)  operates  differently,  as  it  shrivels  ob- 
jects, and  cannot  on  that  account  be  employed  as  a  substitute  for  absolute  alcohoL 

2.  Chromic  acid  is  employed  principally  in  two  aqueous  solutions — [a)  as  a  solu- 
tion  from  O'l  to  0"5  per  cent.  It  is  especially  adapted  for  organs  which  contain 
much  loose  connective  tissue.  This  powerful  solution  gives  to  connective  tissue  a 
strong  consistency,  but  it  labours  under  the  disadvantage  that  it  renders  colour- 
ing difficult.  Objects  remain  in  it  from  one  to  eight  days  ;  they  are  then  placed 
from  three  to  four  hours  under  a  water  tap,  or  if  that  is  impossible,  they  are 
placed  for  the  same  period  in  water,  which  must  then  be  three  or  four  times- 
changed  ;  they  are  then  transferred  for  some  minutes  into  distilled  water,  and 
lastly  they  are  hardened,  while  daylight  is  excluded,  in  alcohol  of  gradually  in- 
creasing strengths.^  {h)  As  0'05  per  cent,  solution,  which  is  prepared  by  diluting 
the  O'l  per  cent,  solution  with  an  equal  amount  of  distilled  water.  Procedure 
as  with  solution  (a) ;  objects  may  remain  twenty-four  hours  in  solution  (6). 

Chromic  acid  solutions  penetrate  slowly  ;  consequently  it  is  necessary,  in  a  pro- 
cess of  twenty-four  hours'  duration,  that  only  small  pieces  (o  to  10  mm.  broad) 
should  be  immersed  in  them. 

3.  Kleinenherg's  sidpho-plcric  acid  (p.  261).  Delicate  objects  (embryos)  are 
immersed  for  five  hours  in  this  fluid  ;  the  more  solid  parts  for  twelve  to  twenty 
hours.  Then,  with  a  view  to  hardening,  transfer  icitliout  the  previous  thorough 
washing  in  water  to  alcohols  of  increasing  strength. 

4.  Al idler'' s  fluid  (p.  261).  Objects  are  placed  in  large  quantities  (400  c.cm.)  of 
this  solution  from  one  to  six  weeks.  Thereafter,  for  four  to  eight  hours,  they  are 
thoroughly  washed  in  water  (flowing  when  possible),  rinsed  for  a  short  time  in  dis- 
tilled water,  and  lastly,  daylight  being  excluded,  they  are  placed  within  alcohols- 
of  increasing  strength.  "  He  ivho  does  not  ivith  scrupulous  conscientiousness  follow 
the  ge)iercd  rules  above  given  for  hardening  fails  to  attain  success,  for  which  failure 
the  innocent  Midler's  solution  is  then  made  responsible  even  by  otherwise  experienced 
microscopists. "     (Stohr. ) 

5.  Osmic  acid  solution  (p.  261).  By  the  use  of  this  solution  the  operator 
avoids  inhaling  vapours  very  irritating  to  the  mucous  membranes.  We  fix,  either 
by  means  of  the  immersion  of  very  small  (5  mm.  broad)  pieces  in  the  acid  (mostly 
employed  in  the  1  per  cent,  solution),  which  is  to  be  diluted  to  the  extent  of 
one  half  with  distilled  water,  and  which  is  usually  employed  only  in  small  quanti- 
ties ;  or  we  fix  by  exposing  the  moistened  object  to  the  vapour  of  osmic  acid.  To 
attain  this,  pour  1  c.cm.  of  2  per  cent,  solution  into  a  small  test-tube  to  the 
height  of  5  cm.  ;  add  the  requisite  amount  of  distilled  water,  and  fasten  the  object 
with  hedgehog  bristles  to  the  lower  surface  of  the  cork  with  which  the 
test-tube  must  be  firmly  closed.  After  the  lapse  of  ten  to  sixty  minutes 
(always  according  to  the  size  of  the  object)  the  small  piece  is  taken  out  and  at  once 
thrown  into  the  liquid  contained  in  the  small  glass.  In  both  cases  the  objects 
continue  for  twenty-four  hours  in  the  acid ;  at  the  same  time  the  glasses  must 
be  well  closed  and  kept  in  the  dark.  The  objects  are  then  taken  out,  rinsed  for  a 
couple  of  minutes  in  distilled  water,  and  hardened  in  alcohols  of  increasing 
strength. 

^  By  this  term  is  understood  first,  Ranvier's  third-part  alcohol ;  then  70  per  cent, 
alcohol ;  then  90  per  cent,  alcohol,  and  lastly,  if  necessary,  absolute  alcohol. 


268  TJIE  PHYSIOLOGY  OF  THE  TISSUES. 

6.  Chroiiio-O'iminm  acetic  arid  (p.  "2(51)  is  an  excellent  fluid  for  the  fixation  of  the 
parts  of  the  nuclens.  Place  small  pieces  (2  to  5  mm.  broad),  quite  fresh,  and  still 
warm  irilh  rifal  heat,  into  4  c.cm.  of  this  liquid,  in  which  they  remain  one  day 
((two  days  are  preferable),  but  in  which  they  may  continue  even  longer.  The 
small  pieces  are  then  thoroughly  washed  for  the  space  of  one  hour  or  longer  iu 
flowing  water  (where  possible),  rinsed  in  distilled  water,  and  hardened  in  alcohols 
of  increasing  strength. 

The  I'lqnixhonce  uHcd  for  fixation  are  of  no  further  use :  they  should  be  thrown  awai/. 

o.  Hardening. — The  best  fluid  for  hardening  is  alcohol  of  gradually 
increasing  strengths.  Here  also  the  rule  that  Ave  should  employ  liquid 
co])iously  holds  good — as  Avell  as  that  of  changing  alcohol  Avhich  has  be- 
come turbid  or  coloured.^  The  exact  process  is  as  follows — After  the 
objects  have  been  fixed  (in  one  of  the  fluids  above  enumerated)  and 
thoroughly  washed  in  Avater,-  they  are  transferred  for  twelve  to  twenty 
hours  into  70  per  cent,  alcohol,  and  after  the  lapse  of  this  period  they 
are  placed  in  90  per  cent,  alcohol,  in  which  the  hardening  is  completed 
iifter  the  further  lapse  of  twenty -four  to  forty-eight  hours  ;  objects  may 
continue  in  this  alcohol  for  months.  The  90  per  cent,  alcohol  that  has 
been  employed  for  hardening  may  be  afterwards  used  for  the  hardening 
of  the  liver  (to  be  used  as  an  embedding  substance  to  facilitate  the 
cutting  of  sections),  or  for  burning  in  a  spirit  lamp. 

6.  Decalcification. — Objects  to  be  decalcified  must  not  be  immersed  fresh 
in  the  decalcifying  fluid ;  they  must,  on  the  contrary,  be  previously 
flxed  and  hardened.  For  this  end,  place  small  bones  (up  to  the  size  of 
the  metacarpus)  and  entire  teeth,  and  pieces  saAved  off"  from  the  larger 
bones  (from  3  to  6  cm.  long),  into  300  c.cm.  of  Miiller's  fluid,  and 
thence,  after  the  lapse  of  tAvo  to  four  Aveeks  (and  after  prcAdous 
thorough  Avashing),  into  150  c.cm.  of  alcohol  of  gradually  increasing 
strength.  After  the  small  bone  has  continued  for  three  days  or 
longer  in  90  per  cent,  alcohol,  it  is  transferred  to  the  decalcifj^ing 
.solution,  Aaz.,  diluted  nitric  acid  (pure  nitric  acid,  9  to  27  c.cm.  added 

^  The  pieces  that  have  been  fixed  in  chromic  acid  and  in  ]M tiller's  fluid  giA'e  ofi' 
€veu  while  in  alcohol,  substances  which,  by  the  simultaneous  influence  of  daylight, 
appear  in  the  form  of  precipitates.  If,  on  the  other  hand,  the  alcohol  is  kept  in 
the  dark,  no  precipitates  are  produced,  but  the  alcohol  assumes  a  yellow  colour, 
remaining  free  from  tm-bidity.  On  this  ground  the  exclusion  of  daylight  has  been 
recommended  ;  it  is  sufficient  to  place  the  glasses  in  a  dark  part  of  the  room.  The 
90  per  cent,  alcohol  also,  so  long  as  it  still  remains  intensely  yellow,  must  be 
changed  once  every  day. 

-  Objects  fixed  in  sulpho-picric  acid  are  excepted  ;  these  are  directly  transferred 
from  this  fluid  into  70  per  cent,  alcohol.  In  this  case  the  70  per  cent,  alcohol 
must  be  changed  several  times  during  the  first  day. 


METHODS  OF  MICROSCOPICAL  RESEARCH.  2G9 

to  300  c.cm.  of  distilled  water).  Here  also,  large  quantities  (300  c.cm. 
at  least)  must  be  employed,  which,  at  the  beginning,  must  be  changed 
daily,  but,  subsequently,  every  four  days  until  the  decalcification  is 
accomplished.  We  hasten  the  process  by  means  of  punctiuring  mth  an 
old  needle,  and  incisions  with  a  scalpel.-^  Decalcified  bone  is  flexible, 
soft,  and  admits  of  being  easily  cut.  Foetal  bones,  heads  of  embryos, 
etc.,  are  decalcified  in  nitric  acid  of  a  weaker  kind  (1  c.cm.  of  pure  acid 
to  99  c.cm.  of  distilled  water),  or  in  500  c.cm.  of  saturated  acpieous 
solution  of  picric  acid.  The  process  of  decalcification  requires  several 
weeks  in  the  case  of  thick  bones ;  in  the  case  of  foetal  and  small  bones, 
three  to  twelve  days.  AVhen  decalcification  is  completed,  the  bones 
are  thoroughly  washed,  from  six  to  twelve  hours,  in  Avater,  and  again 
hardened  in  alcohols  of  increasing  strengths.  It  not  unfrequently 
happens,  in  the  case  of  beginners,  that  the  bone  is  placed  in  alcohol 
when  the  decalcification  is  yet  incomplete,  and  then  turns  out  to  be  use- 
less for  histological  investigation.  In  such  cases,  the  entire  process  of 
decalcification  must  be  repeated.  If  objects  lie  too  long  in  the  decal- 
cifying fluid,  decomposition  is  induced. 

7.  Sections.- — The  razor  must  be  sharp  ;  the  success  of  the  prepara- 
tions depends  on  the  sharpness  of  the  blade.  In  section-cutting,  the 
blade  must  be  moistened  with  alcohol  (not  with  water,  which  moistens 
the  blade  only  to  an  imperfect  extent).  For  this  end,  dip  the  blade, 
before  every  third  or  fourth  section,  into  a  flat  glass  dish  filled  with  30 
c.cm.  of  90  per  cent,  alcohol,  which  serves  also  for  the  reception  of  the 
prepared  sections.  The  blade  must  be  held  in  a  horizontal  position, 
lightly  grasped,  with  the  thumb  pressed  against  the  edge,  the  fingers 
against  the  hinder  part  of  the  blade,  and  the  back  of  the  hand 
directed  upwards.  First  of  all,  cut  a  slice  from  the  object  so  as  to 
expose  a  smooth  siurface,  and  then  sej)arate  from  the  object,  with 
one  .stroke,  a  piece  of  suitable  thickness.  Now  begins  the  making 
of  successive  sections ;  this  must  always  be  clone  as  smoothly  as 
possible,  with  symmetrical  thinness,  and  A\dth  one  light,  not  too  rapid, 
stroke.-     We  then  place  the  dish  on  a  black  background,  and  pick  out 

1  The  needle  and  the  scalpel  must  be  carefully  cleaned  immediately  after  use. 

"  The  blade  is  not  to  be  pressed  through  an  object,  but  to  be  drawn  through  it. 
It  is  wise  to  make  always  a  very  large  number  (10  to  20)  of  sections,  which  are 
then  to  be  transferred  into  the  glass  dish  with  a  needle  or  by  the  immersion  of 
the  knife. 

Fine  sections,  which  either  have  not  been  stained,  or  have  already  been  stained 
throughout,  can  best  be  cut  and  floated  off  by  the  edge  of  the  razor  being  mclined 
directly  on  the  slide. 


270  THE  PHYSIOLOGY  OF  THE  TISSUES. 

the  best  sections.  The  thinnest  sections  are  not  alimijs  the  most  useful ;  for 
many  prc])arations,  e.g.  a  section  through  the  coats  of  the  stomach, 
thicker  sections  are  more  to  lie  recommended.  For  specimens  intended 
for  general  inspection  M-ith  low  powers,  let  the  operator  produce  large, 
thick  sections  ;  for  small  structures  suitable  for  high  powers,  he  must 
cut  thin  ones.  For  high  poAvers,  the  very  smallest  fragments  of 
1  to  2  mm.  broad,  obtained  by  means  of  the  superficial  manipulation  of 
the  knife,  or  marginal  parts  of  somewhat  thicker  sections,  often  suffice. 
If  the  object  to  be  dissected  is  too  small  to  be  held  by  the  fingers,  it 
ought  to  be  imbedded.  The  simplest  method  is  that  of  imbedding  in 
liver. 

Take  either  ox's  liver  or,  what  is  better,  human  fatty  or  amyloid  liver  (to  be  ob- 
tained from  the  pathological  department),  and  cut  it  into  thick  pieces  (3  cm.  in 
height,  2  in  breadth,  and  2  in  thickness) ;  these  are  immediately  thrown  into  90  per 
cent,  alcohol,  which  must  be  changed  the  next  day.  After  three  to  live  days  longer, 
the  liver  possesses  the  requisite  hardness.  Now,  cut  one  of  these  pieces  from 
above  down  to  the  half  of  its  height,  and  squeeze  the  object  to  be  cut  into  the 
fissure  so  produced.  If  the  object  be  too  thick,  the  operator  can,  with  a  small 
;scalpel,  cut  furrows  in  the  liver,  into  which  the  object  is  fitted. 

Most  objects  may  be  cut  in  liver,  and  very  delicate  sections  can  thus 
be  obtained  after  some  practice,  regularly  carried  on  for  a  few  weeks. 

8.  Colouring,  Staining. — The  particular  solution  of  the  colouring 
matter  must  always  be  filtered  before  use.  Small  funnels  are  made  of 
-double  thicknesses  of  filter  paper  (5  c.cm.),  and  fastened  in  a  cork  frame 
which  has  been  prepared  by  means  of  the  excision  of  a  jiiece  2  cm. 
broad  out  of  a  cork  plate  5  cm.  Ijroad.  The  frame  of  cork  is  fixed  on 
four  long  pins.  Such  funnels  can  be  used  several  times.  Funnels  and 
frames  are  to  be  employed  only  for  one  and  the  same  fluid. 

1.  NxLcleus  Htainhuj  ^cith  hamatoxijl hi  (p.  2Q2).  Filter  .3  to  4  c.cm.  of  colouring 
solution  into  a  watch  glass  and  introduce  the  sections  into  it.  The  time  in  which 
the  sections  acquire  colour  is  very  various.  Sections  in  alcohol  of  fixed  and 
hardened  objects  acquire  colour  in  one  to  three  minutes.  If  the  fixation  has  been 
efi'ected  with  Mtiller's  fluid,  the  objects  must  be  immersed  someM'hat  longer  (five 
minutes)  in  the  fluid. 

[Sections  of  objects  fixed  in  strong  chromic  acid,  or  of  those  not  entirely  free 
from  acid,  often  take  on  colour  very  slowly,  and  sometimes  not  at  all.  We  can 
remedy  this  inconvenience  either  by  means  of  protracted  preservation  for  two  or 
three  months  in  90  per  cent,  alcohol,  to  be  changed  two  or  three  times,  or  by 
immersing  such  sections,  before  they  are  brought  into  the  hfematoxylin,  for  five  to 
ten  minutes,  in  a  watch  glass,  along  with  5  c.  cm.  of  distilled  water,  to  which  three 
to  seven  drops  of  35  per  cent,  caustic  potash  are  added.  We  then  transfer  the 
sections  for  one  to  two  minutes  into  a  watch  glass  with  pure  distilled  water,  and 
thence  into  the  hccmatoxylin.  Such  sections  also  become  coloured  after  five  to 
ten  minutes.] 


METHODS  OF  MICROSCOPICAL  RESEARCH.  271 

The  sections  must  next  be  transferred  from  the  colouring  matter  into  a  watch  glass 
containing  distilled  water,  rinsed,  i.e.  moved  somewhat  with  the  needle,  in  order 
to  free  them  from  the  surplus  coloiiring  matter,  and,  after  the  lapse  of  one  to  two 
minutes,  transferred  into  a  large  dish  filled  with  30  c.cm.  of  distilled  water.  The 
sections  must  remain  here  at  least  five  minutes,  during  which  their  purple  colour 
gradually  passes  over  into  a  beautiful  dark  blue,  which  becomes  all  the  more  pure 
the  longer  (twenty-four  hours)  we  allow  the  sections  to  be  in  the  water. 

The  sections  at  first  appear  entirely  blue.  About  five  minutes  after,  in  many 
cases  only  after  the  lapse  of  hours,  the  difi"erentiation  is  first  effected,  so  as  to 
admit  of  many  details  being  perceived  even  with  the  naked  eye. 

The  colouring  matter  which  has  been  used  is  again  poured  back  through  the 
filter  into  the  bottle  containing  the  htematoxylin  solution.  The  watch  glass  must  be 
immediately  cleaned.  It  is  recommended  to  beginners  to  leave  the  sections  in  the 
dye  for  a  time,  ranging  variously  from  one,  three,  to  five  minutes,  and  then  to 
watch  what  length  of  time  is  adapted  for  successful  staining.  In  the  case  of 
hsematoxylin  colouring,  the  principal  thing  is  careful  washing. 

2.  Diffusive  staining — for  the  staining  of  protoplasm  and  of  the  intercellular 
substances,  (a)  Sloio  colouring.  A  small  drop  of  neutral  solution  of  carmine 
(p.  262)  is  placed  by  a  glass  rod  in  a  dish  filled  with  20  c.cm.  of  distilled  water  ; 
at  the  bottom  of  this  dish  there  lies  a  small  piece  of  filter  paper. ^  The  sections 
must  lie  in  the  fluid  over  night.  The  moi'e  rose-tinted  the  fluid  is,  the  longer 
the  colouring  process  lasts,  and  the  brighter  the  section  becomes.  The  beginner 
is  always  inclined  to  regard  the  pale-rose  tint  as  unlikely  to  produce  a  good 
stain,  until,  on  the  next  day,  the  dark-rose  sections  turned  to  red  teach  him  a 
better  lesson.  But  this  mode  of  colouring  is  seldom  applicable  for  its  own 
sake  ;  on  the  other  hand,  it  is  to  be  recommended  for  compound  staining. 
Colour  first  of  all  with  carmine  solution,  then  with  hsematoxylin.  (b)  Bapid 
colouring.  Pour  10  drops  of  eosin  solution  (p.  263)  into  3  to  4  c.cm.  of  dis- 
tilled water.  The  sections  remain  therein  one  to  five  minutes,  they  are  then 
for  a  short  time  "rinsed  out"  (as  in  the  case  of  hfematoxylin  colouring)  in  a 
watch  glass  with  distilled  water  and  transferred  for  ten  minutes  into  30  c.cm.  of 
distilled  water.  The  colouring  may  be  employed  alone  or  combined  with  haema- 
toxylin.  The  entire  process  of  hsematoxylin  colouring  is  to  be  completed  first, 
and  the  eosin  colouring  next. 

3.  Staining  of  the  chromatic  substance  in  nuclear  division.  The  objects  are 
placed,  from  sixteen  to  forty-eight  hours  (the  longer  the  better),  in  only  3  c.cm. 
of  solution  of  safi'ranin  (p.  263).  Then  the  solution,  together  with  the  sections, 
is  poured  out  into  a  plate  containing  distilled  water ;  entirely  opaque  sections 
are  lifted  out  with  the  needle  and,  in  order  to  change  their  colour,  placed  in  5 
c.cm.  of  hydrochloric-acid-alcohol.  If  the  section  does  not  yield  much  colour 
(after  a  half  to  two  minutes),  it  is  transferred  into  5  c.cm.  of  pure  absolute 
alcohol,  and  after  a  minute  cleared  up  and  mounted.  Too  long  continuance  in 
hydrochloric-acid-alcohol  (just  as  in  absolute  alcohol) — may  lead  to  a  too  great 
change  of  colour  of  the  preparation.  We  employ  the  safi'ranin  colouring  only  after 
precedmg  fixation  with  chromo-osmium  acetic  acid. 

4.  Staining  in  mass.  Colouring  of  the  nucleus  in  entire  pieces  of  organs  pre- 
vious to  their  separation  into  sections.  Fixed  and  hardened  objects  are,  when 
small   (5    mm.    broad),   transferred  for  twenty-four  hours  to  30  c.cm.    of  borax 

1  If  this  is  neglected,  the  sections  acquire  colour  only  on  one  side. 


272  THE  FJlYiSlOLOUV  OF  THE  TJS.'SUE^. 

carmine  ;  when  larger,  for  two  to  three  days ;  they  are  transferred  out  of 
this  directly  into  25  com.  of  hydrochloric-acid-(70  per  cent.)-alcohol  (p.  263) 
— (the  borax  carmine,  after  being  used,  is  poui-ed  back  into  the  flask).  After 
the  lapse  of  a  few  minutes,  the  alcohol  is  red,  and  must  now  be  replaced  by  new 
hydrochloric-acid-alcohol.  After  nearly  a  quarter  of  an  hour,  the  alcohol  is  again 
changed,  and  this  clianging  is  continued  without  intermission  until  the  alcohol  is  no 
longer  coloured.^  The  piece  is  then  transferred  into  00  per  cent,  alcohol,  and  if 
it  has  not,  after  twenty-four  hours,  become  hard  enough  for  cutting,  it  is  trans- 
fen-ed  for  twenty-four  hours  or  more  into  absolute  alcohol. 

5.  Picrocarminc  Double  dyeing,  nuclei  and  connective  tissue  red,  protoplasm 
yellow.  Filter  o  c.cm.  of  the  fluid  into  a  watch  glass.  The  period  of  time  in 
which  picrocarmine  operates  varies  according  to  the  tissue,  and  can  only  be 
approximately  given.  After  the  colouring  has  beeu  completed,  the  colour  is 
again  filtered  back  into  the  flask,  and  the  object  transferred  for  ten  to  thirty 
minutes  into  10  c.cm.  of  distilled  water.  It,  of  course,  loses  colour  under  the 
cover-glass.  If  the  object,  e.g.  a  section,  is  to  be  placed  in  absolute  alcohol,  it 
must  not  remain  there  long  (one  to  two  minutes),  as  the  alcohol  extracts  the 
yellow  colour.-  Picrocarmine  is  especially  employed  in  investigations  of  fresh 
objects.  If  the  solution  is  good,  we  secure  a  beatxtiful  colour,  which  comes  out 
brilliantly,  especially  with  the  subseqiient  application  of  glycerine  acidulated 
with  a  few  drops  of  acetic  acid. 

6.  Coloimiuj  of  nuclei  icith  aniline  dyes.  The  best  aniline  dyes  for  this  purpose 
are  vesuvin  and  methyl-violet  B.  Filter  4  c.cm.  of  the  fluid  into  a  watch 
glass,  and  place  the  sections  in  it.  They  become,  after  two  to  five  minutes, 
coloured  quite  dark ;  they  are  then,  for  a  short  time,  washed  in  5  c.cm,  of 
distilled  water,  and  transferred  to  a  watch  glass  containing  absolute  alcohol, 
where  they  lose  much  colour.  After  a  few  minutes  (three  to  five),  when  the 
sections  have  become  lighter,  we  can  recognize  individual  parts  {e.g.  the 
glands  in  the  case  of  the  skin)  with  the  naked  eye.  The  sections  are  now 
transferred  into  a  second  watch  glass  with  5  c.cm.  of  absolute  alcohol,  and,  after 
two  miniites,  cleared  up  and  mounted  in  dammar  varnish  (p.  2G1).  The  resiilt 
is  a  very  beautiful  colouring  of  the  nucleus.  Vesu^^n  should  be  kept  in 
glycerine.     A  disadvantage  lies  in  the  large  consumption  of  absolute  alcohol. 

7.  Silver  staining — for  the  representation  of  cell  boundai-ies  and  colouring  of 
cement  substances.  The  use  of  metal  instruments  is  to  be  avoided  ;  use  a  glass 
rod.  Instead  of  pins,  use  hedgehog  bristles.  The  object  is  immersed  in 
10  to  20  c.cm,  of  1  per  cent.,  or  weaker,  solution  of  nitrate  of  silver  (p.  261, 
par.  15).  After  half  a  minute  to  ten  minutes  (always  according  to  the  thickness 
of  the  object)  it  is  taken  out  of  the  fluid — which  has  meanwhile  assumed  an 
almost  milky  hue — by  a  glass  rod,  rinsed,  and  exposed  to  direct  sunlight  in  a 
large  white  dish  (a  porcelain  plate)  containing  100  c.cm.  of  distilled  water.  After 
the  lapse  of  a  few  minutes,  a  slight  browning  will  supervene,  the  sign  of  the  suc- 
cessful reduction   of  the   silver.      Immediately   on  the  object  becoming  a  dark 

1  This  may  occupy  one  to  three  days  ;  during  the  first  day,  change  every  two 
hours  ;  dui'ing  the  subsequent  time,  every  four  hours.  If  the  operator  wishes  to 
be  economical,  he  may  slowly,  with  a  needle,  push  the  object  out  of  the  layer  of 
the  red  fluid  in  which  it  lies,  and  bring  it  to  another  uncoloured  part  of  the  fluid. 

2  This  deprivation  of  colour  can  be  avoided,  if  we  throw  into  the  watch  glass  a 
small  crystal  of  picric  acid  along  with  the  absolute  alcohol. 


METHODS  OF  MICROSCOPICAL  RESEARCH.  273 

reddish-brown  (usually  after  five  to  ten  minutes),  it  is  taken  out  and  transferred 
to  a  watch  glass  containing  distilled  water,  to  which  a  couple  of  grains  of  common 
salt  are  added,  and,  after  five  to  ten  minutes,  it  is  put  for  preservation  in  30  c.cm. 
of  70  per  cent,  alcohol,  in  darkness.  After  three  to  ten  hours,  substitute 
90  per  cent,  alcohol  for  the  alcohol  of  70  per  cent.  The  substance  is  im- 
mersed in  the  solution  of  silver  in  the  dark.  The  reduction,  on  the  contrary, 
must  be  accomplished  in  the  sunlight.^  If  there  is  no  sunshine,  lift  the 
object  (after  it  has  been  taken  out  of  the  silver  solution  and  washed  thoroughly 
for  a  short  time  in  distilled  water)  into  30  c.  cm.  of  70  per  cent,  (later  on  into  90 
per  cent. )  alcohol,  in  the  dark,  and  expose  it,  while  in  the  alcohol,  to  the  light  at 
the  first  blink  of  sunshine. 

8.  Gold  staining — for  demonstrating  the  terminations  of  the  nerves.  Steel 
instruments  must  not  be  immersed  in  the  gold  solution.  All  manipulations  in 
the  gold  solution  are  to  be  undertaken  with  glass  rods  or  with  small  wooden 
rods.  Heat  in  a  small  test-tube,  to  boiling,  8  c.cm.  of  1  per  cent, 
solution  of  chloride  of  gold  +  2  c.cm.  of  formic  acid  (p.  261).  The  mixture 
must  boil  up  thrice.  In  the  cooled  mixture,  very  small  pieces  of  tissue  (at  the 
most  5  mm.  broad)  are  immersed  for  the  space  of  an  hour,  and  kept  in  the 
dark  ;  they  are  then  for  a  short  time  thoroughly  washed  with  distilled  water  in  a 
watch  glass,  and  exposed  to  the  light  (not  necessarily  sunshine)  in  a  mixture  of  10 
c.cm.  of  formic  acid  with  40  c.cm.  of  distilled  water.  The  reduction  by  which 
the  small  pieces  become  dark  violet  on  the  outside  is  accomplished  very  slowly 
(often  after  twenty-four  to  forty-eight  hours  at  the  earliest).  The  pieces  are  then 
transferred  to  30  c.cm.  of  70  per  cent,  alcohol,  and,  on  the  following  day,  to  90 
per  cent,  alcohol,  in  which,  for  the  prevention  of  further  reduction,  they  must 
remain  for  eight  days. 

9.  Injection. — The  filling  of  the  blood  vessels  and  of  the  lymphatic 
vessels  ■vvith  coloured  substances  is  a  peculiar  art,  which  can  be  ac- 
quired only  by  means  of  much  practice.  Knowledge  of  the  many  little 
artifices  employed  can  scarcely  be  acquired  by  lectures  or  even  with 
all  the  help  of  copious  directions.  Practical  instruction  is  here 
indispensable. 

Anyone  wishing  to  inject  must  have  a  syringe,  working  well,  and 
provided  with  an  easily  movable  piston  and  nozzles  of  various  diameters. 
As  injection  material  use  Griibler's  Berlin  blue,  3  grams,  dissolved  in 
600  c.cm.  of  distilled  water.  Begin  >vith  the  injection  of  single  organs, 
e.g.  the  liver,  which  possesses  the  advantage  that  even  an  incomplete 
filling  of  its  vessels  yields  useful  results.  Place  the  injected  object  for 
two  to  four  weeks  in  Miiller's  fluid,  and  harden  it  in  alcohol.  The 
sections  must  not  be  too  thin. 

10.  Mounting  and  Preservation  of  Preparations. — The  prepared  sections, 
etc.,  are  now,  with  a  view  to  microscopical  investigation,  transferred  to 

^  The  reduction  doubtless  succeeds  also  in  ordinary  daylight,  but  it  is  efl'ected 
slowly,  and  yields  less  distinct  forms. 

I.  S 


274  THE  PHYSIOLOGY  OF  THE  TISSUES. 

a  slide  and  placed  under  a  cover-glass.  The  media  in  which  the  sections 
are  examined  are  either  (1)  Avater;  or,  if  it  is  desired  to  brighten  up 
and  preserve  the  sections,  (2)  glycerine;  or  (3)  dammar  solution. 

Transference  to  the  slide  is  effected  thus — the  investigator  places 
first  of  all  a  small  drop  of  the  requisite  fluid  on  the  middle  of  the  slide ; 
he  then  lifts  the  section  with  the  spatula  and  lays  it  on  the  slide.  It  is 
a  good  method  to  lift  very  delicate  sections  with  the  end  of  a  glass  rod, 
and  to  lay  them  on  the  slide  hy  rolling  it  round.  When  the 
section  lies  smoothly,  place  a  cover-glass  on  it.^  The  latter  must 
be  grasped  by  the  edge.  In  the  act  of  covering,  the  cover-glass  is 
placed  on  the  slide,  resting  on  the  left  edge,  and  then  it  is  slowly 
lowered  on  to  the  preparation,  while  the  under  surface  of  the  cover- 
glass  is  supported  by  a  needle  held  in  the  right  hand.  It  is  still 
simpler  to  place  a  drop  of  the  requisite  fluid  on  the  lower  surface  of  the 
cover-glass  and  then  to  allow  the  cover-glass  to  fall  gently  on  the 
preparation.  The  fluid  in  which  the  section  happens  to  be  must 
fill  up  the  entire  space  between  the  cover-glass  and  the  slide. 
If  a  sufiiciency  of  fluid  is  lacking  (which  is  recognizable  by  large  air 
bubbles  appearing  under  the  cover-glass),  place,  with  the  point  of  the  glass 
rod,  one  drop  more  of  the  fluid  on  the  rim  of  the  cover-glass.  If  there  is 
a  sui^erabundance  of  fluid — and  this  usu.ally  occurs,  especially  with  be- 
ginners— the  liquid  which  has  oozed  out  from  under  the  rim  of  the  cover- 
glass  must  be  absorbed  by  filter  paper.  The  upper  surface  of  the  cover-glass 
must  always  he  dry.  Remove  small  air  bubbles  under  the  cover-glass  by 
means  of  frequently  carefully  raising  and  lowering  it  with  the  needle. 

1.  Never  neglect  to  examine  uncoloured  as  well  as  coloured  sections  in  water  or 
in  solution  of  common  salt,  as  in  these  many  details  of  structure,  e.g.  connective 
tissue  formations,  distinctly  emerge  to  view,  whilst  the  same,  under  the  brightening 
influence  of  glycerine  or  of  dammar  varnish,  almost  entirely  elude  observation. 
Objects  mounted  in  water  or  even  in  a  solution  of  common  salt  cannot  be  pre- 
served. 

2.  Preparations  mounted  in  glycerine  may  be  preserved.  In  order  to  prevent 
removal  of  the  cover-glass,  fix  it  with  cover-glass  cement.  As  a  previous 
condition  of  success,  the  rim  of  the  cover-glass  must  be  completely  dry,  for 
cement  adheres  only  to  dry  surfaces.  To  dry  the  slide  round  the  cover-glass, 
first  absorb  with  filter  paper  the  glycerine  oozing  from  under   the  rim  of  the 

1  Investigations  with  low  magnifying  powers  without  a  cover-glass  are  only 
admissible  in  the  most  superficial  examinations,  as,  for  example,  to  ascertain  if 
object  has  been  thoroughly  teazed  out.  In  all  other  cases,  the  cover-glass  is 
indispensable.  In  order  to  be  persuaded  of  this,  let  anyone  examine  an  uncovered 
section,  then  let  him  cover  it  with  a  cover-glass  and  examine  it  again.  Many  a 
good  preparation,  the  covering  of  which  has  been  neglected,  appears  unfit  for  use. 
Investigations  with  high  powers  without  a  cover-glass  are  in  general  inadmissible. 


METHODS  OF  MICROSCOPICAL  RESEARCH.  275 

oover-glass,  and  then  with  a  cloth  moistened  with  90  per  cent,  alcohol  (the  cloth 
being  drawn  over  the  point  of  the  finger),  carefully  wipe  the  slide  all  round 
the  cover-glass,  without  touching  the  latter.  Then  heat  a  glass  rod  and  plunge 
it  into  the  cement,^  and  bring  four  drops  on  to  the  four  corners  of  the  cover- 
glass.  Then  lead  the  cement  round  the  margins  of  the  cover-glass,  so  as  to  cover 
the  cover-glass  on  the  one  hand  and  a  portion  of  the  slide  on  the  other,  to  the 
breadth  of  1  to  3  mm.  Finally,  smooth  with  the  heated  rod  the  upper  surface  of 
the  layer  of  cement. 

Preparations  preserved  in  glycerine  are  often  beautifully  transparent  on  the 
second  or  third  day.  Hsematoxylin  and  other  colouring  matters  grow  dim  in 
glycerine  after  some  time  ;  on  the  contrary,  picrocarmine  and  carmine  retain 
their  colour. 

3.  Mounting  objects  in  dammar  varnish  is  an  excellent  method  of  preservation. 
Dammar  varnish  has,  as  opposed  to  glycerine,  the  advantage  of  retaining  colours, 
but  with  the  drawback  that  it  renders  objects  more  transparent  than  dilute 
glycerine  and  frequently  causes  delicate  structures  to  disappear. 

Sections  which  happen  to  be  in  water  or  alcohol,  cannot  be  placed  at  once 
into  dammar  varnish  ;  they  must  he  previously  entirely  freed  from  water.  To  this 
•end,  the  sections  are  transferred  to  a  covered  watch  glass  containing  4  c.cm.  of 
absolute  alcohol,  in  which  they  may  remain  for  two  minutes  in  the  case  of  thin 
sections,  and  for  ten  minutes  in  the  case  of  thicker  ones.^  Next  we  fish  out  the 
sections  with  the  needle  (very  delicate  sections  with  spatula  or  section  lifter)  and 
transfer  them,  with  a  view  to  clearing  up,  into  a  watch  glass  containing  3 
c.cm.  of  lavender  oil  or  oil  of  cloves.'  Place  the  dish  on  black  paper  so  as 
to  observe  the  sections  becoming  transparent.  Avoid  breathing  into  the 
watch  glass,  as  immediate  turbidity  of  the  lavender  oil  is  the  result.  If  indi- 
vidual portions  of  the  sections  do  not  become  transparent  after  two  or  three 
minutes  (in  this  case  the  portions  appear  a  dirty  white  when  the  light  falls  on  them 
and  dark  brown  when  the  light  passes  through  them),  the  section  has,  in  that 
case,  not  been  freed  from  water  and  it  must  once  again  be  transferred  to  absolute 
alcohol.  After  the  clearing  up  has  been  completed,  the  section  is  transferred  to 
a  dry  slide  and  the  superfluous  oil  *  carefully  wiped  off  with  filter  paper,  or  with 

^  Glass  rods  crack  very  easily  when  heated,  and  metal  rods  are  preferable,  but 
they  cool  too  rapidly.  We  can  to  some  extent  avoid  the  cracking  by  heating  the 
^lass  rods,  while  they  are  being  continually  turned  round,  up  to  a  red  heat.  Glass 
rods  heated  for  only  a  short  time  crack  immediately  on  being  plunged  into  the 
cement. 

2 Beginners  should  transfer  the  sections  out  of  the  water,  first  of  all  into  4  c.cm. 
of  90  per  cent,  alcohol,  and  then  quickly  into  the  same  quantity  of  absolute  alcohol. 

'  We  can  also  bring  the  section  directly  out  of  the  absolute  alcohol  on  to  the  slide, 
wipe  off  the  superfluous  alcohol  and  place  upon  it  a  drop  of  lavender  oil.  At  first 
the  oil  always  trickles  off  from  the  section  and  it  must  be  guided  back  again 
by  a  needle  ;  after  complete  clearing  up,  which  we  can  observe  under  the 
microscope  with  a  low  power,  the  oil  is  as  soon  as  possible  wiped  off  and  a  cover- 
glass  with  dammar  varnish  placed  over  it.  If  we  examine  the  uncovered  section 
in  oil,  section  and  oil  may  become  obscured  by  the  breath  ;  in  such  cases,  let  the 
turbid  oil  trickle  off  and  substitute  a  drop  of  fresh  oil. 

■*  The  oil  in  the  watch  glass  used  in  clearing  up  may  again  be  poured  back  into 
the  bottle. 


276  THE  PHYSIOLOGY  OF  THE  TISSUES. 

a  linen  duster  wrapped  round  the  forefinger,  and  a  cover-glass  is  placed  on  it,. 
to  the  under  surface  of  which  a  drop  of  dammar  varnish  has  been  attached.. 
When  several  sections  are  brought  under  one  cover-glass,  in  the  first  place 
arrange  the  sections  in  close  proximity  by  means  of  the  needle,  then  with  the^ 
glass  rod  spread  the  dammar  varnish  over  the  under  surface  of  the  cover-glass,. 
in  a  layer  proportionately  thin  throughout,  and  place  the  cover-glass  over  the 
sections.  Large  air  bubbles  are  got  rid  of  by  placing  a  small  drop  of  dammar 
varnish  near  the  rim  of  the  cover-glass. 

It  not  unfrequently  occurs  in  the  case  of  beginners  that  the  varnish  becomes- 
turbid  and  finally  renders  the  entire  preparation,  or  parts  of  it,  opaque.  The 
reason  is,  that  the  section  has  not  been  freed  from  water.  In  the  case  of 
slight  turbidity  (which  reveals  itself  under  the  microscope  as  consisting  of 
minute  drops  of  water),  slight  heating  of  the  slide  may  be  a  remedy.  In  the  case 
of  denser  turbidity,  place  the  entire  slide  in  oil  of  turpentine,  carefully  lift  oflf 
the  cover-glass  half  an  hour  afterwards,  place  the  sections  in  oil  of  turpentine 
for  two  minutes  to  dissolve  the  adhering  varnish,  and  lastly  place  it,  with  Or 
view  to  the  complete  removal  of  the  water,  into  4  c.  cm.  of  absolute  alcohol,  which 
must  be  changed  after  five  minutes.  The  lavender  oil  and  dammar  varnish  pro- 
cess is  then  repeated. 

Dammar  varnish  dries  very  slowly,  and  therefore  the  slides  must  not  be  placed 
on  their  side. 

The  successive  processes  through  which  a  fresh  object  has  to  pass  until  it  is  pre- 
served as  a  finished  stained  section  is  a  veiy  long  one.  When,  for  example,  it  is 
prescribed  in  the  appendix  detailing  special  methods  thus — "  Fix  in  Miiller's  fluid 
fourteen  days,  harden  in  gi'adually  concentrated  alcohol,  colour  the  section  in  car- 
mine and  hifimatoxylin,  mount  in  dammar  varnish" — the  process  is  as  follows: — 
The  fresh  object,  1  c.cm.  in  size,  is  placed  in  200  c.cm.  of  Miiller's  fluid,^  which, 
immediately  after  turbidity  has  set  in  (usually  after  one  hoiir),  is  changed. 
After  twenty-four  hours  the  fluid  is  again  changed  ;  the  object  now  remains  in  it 
for  a  period  of  fourteen  days.  After  the  expiration  of  this,  it  is  washed  in  flowing 
water  for  one  to  four  hours  ;  then  placed  in  20  c.cm.  of  distilled  water  for  fifteerr 
minutes  ;  then  in  50  c.cm.  alcohol  (70  per  cent.)  and  in  the  dark  for  twenty-four 
hours  ;  then  bx  50  c.cm.  of  90  per  cent,  alcohol  for  twenty -four  houi's,  when  the 
90  per  cent,  alcohol  is  changed. 

The  fixed  and  hardened  object  may  now  be  cut  after  a  suitably  long  time,  during 
which  the  90  per  cent,  alcohol  is  perhaps  once  more  changed.  The  section  is- 
taken  out  of  the  alcohol  and  transferred  into  30  c.cm.  of  dilute  carmine  solution  for 
twenty-four  hours  ;  then  into  5  c.cm.  of  distilled  water  for  fifteen  minutes  ;  then 
into  3  c.cm.  of  hcematoxylin  for  five  minutes;  then  into  20  c.cm.  of  distilled 
water  for  ten  minutes  to  two  hours  ;  then  into  5  c.cm.  of  absolute  alcohol  for  ten 
minutes  ;  then  into  3  c.  cm.  of  lavender  oil  or  oil  of  cloves  for  two  minutes,  and  lastly 
the  section  is  mounted  in  dammar  varnish. 

11.  Investigation  of  Fresh  Objects. — This  is  placed  at  the  end  of  all  the* 
other  methods  because  it  is  the  most  difficult,  and  presupposes  a  some- 
what practised  eye.     Experience  is  most  easily  acquired  by  the  investi- 

^  The  directions  for  size  are  calculated  only  for  one  piece  1  c.cm.  large.  When. 
the  piece  is  larger,  or  when  several  pieces  are  submitted  to  the  process,  more  fixing; 
and  hardening  fluid  must,  of  course,  be  employed. 


METHODS  OF  MICROSCOPICAL  RESEARCH.  277 

gation  of  objects  dlredidij  prepared  (hardened,  coloured,  etc.).  If  anyone 
las  once  distinctly  seen  and  studied  details  of  structure  seen  in  stained 
specimens,  it  is  not  so  difficult  to  make  out  these  even  in  fresh  objects. 
That  which  now  follows  recjuires  attention.  Slides  and  cover-glasses 
XQUst  not  be  greasy.  Clean  them  with  alcohol  and  dry  them  with  a  clean 
■cloth.  Then  place  one  drop  of  '75  per  cent,  solution  of  common  salt 
on  the  slide,  next  place  in  it  a  small  piece  of  the  object  to  be  investigated, 
and  cover  the  latter  with  a  cover-glass.  In  this  process,  all  pressure 
must  be  carefully  avoided.  In  the  case  of  very  delicate  objects,  lay  two 
small  strips  of  paper  on  the  slide  so  that  the  cover-glass  "will  rest  on  them 
without  pressing  the  object  itself.  If  the  object  requires  no  further 
manipulation,  the  observer  should  run  round  the  edge  of  the  cover-glass 
s.  thin  layer  of  paraffin  to  prevent  evaporation.  Melt  on  an  old  scalpel 
Si  large  piece  of  paraffin,  nearly  as  large  as  a  lens,  and  let  it  run,  not 
from  the  point,  but  from  the  edge  of  the  scalpel,  on  to  the  rim  of  the 
cover-glass.  Gaps,  here  and  there,  may  be  filled  up  by  applying  the  heated 
«nd  of  the  scalpel.  It  is  easy  to  subject  fresh  objects  to  the  operation  of 
certain  reagents  (acetic  acid,  caustic  potash,  colouring  matters)  while 
Tinder  the  microscope.  One  may  remove  a  part  of  the  medium  in  which 
the  object  lies  (as,  for  example,  the  solution  of  common  salt),  and 
substitute  another  fluid  in  its  place.  To  do  this,  place  a  drop,  e.g.  of 
picrocarmine,  with  a  glass  rod  on  the  right  rim  of  the  cover-glass.  If 
the  drop  does  not  reach  entirely  to  the  rim  of  the  cover-glass,  do  not 
incline  the  slide  to  it,  but  guide  the  drop  with  a  needle  to  the  margin  of 
the  cover-glass.  We  see  now  that  a  little  of  the  colouring  matter  mixes 
with  the  solution  of  common  salt,  but  that  a  regular  flow  of  the  colouring 
fluid  does  not  take  place.  In  order  to  secure  this,  place  a  little  bit  of 
filter  paper  on  the  left  rim  of  the  cover-glass,^  and  the  picrocarmine  ^vill 
soon  occupy  the  entire  under  surface  of  the  cover-glass.^  Lay  the 
filter  paper  aside,  and  allow  the  stain  to  operate.  When  the  colouring 
las  been  completed — a  fact  which  can  be  always  observed  under  the 
microscope — place  on  the  right  rim  of  the  cover-glass  a  droj),  e.g.  of 
_glycerine,  to  which  add,  in  cases  of  colouring  by  picrocarmine,  as  much 
acetic  acid  as  will  drop  from  a  needle  dipped  once  into  it  (thus  a  small 
drop),  and  then  lay  the  filter  paper  again  on  the  left  side  of  the  rim. 
In  this  manner,  we  can  conduct  an  entire  series  of  fluids  under  the  cover- 
glass,  and  test  their  action  on  the  tissues.     Certain  of  the  fluids,  picro- 

1 1  cut  out  a  piece  4  cm.  long,  2  cm.  broad,  notch  it  transversely,  and  place  the 
paper  roof  so  formed  on  the  slide  in  such  a  manner  that  it  touches  the  left  rim  of 
-the  cover-glass  with  the  rim  entirely  and  straightly  cut,  and  2  cm.  broad. 

2  When  the  first  drop  has  penetrated,  place  (always  in  proportion  to  what  is 
3ieeded)  two  or  three  further  drops  on  the  right  of  the  cover-glass. 


278  THE  PHYSIOLOGY  OF  THE  TISSUES. 

carmine  for  example,  must,  after  preceding  fixation  A\ath  osmic  acid, 
remain  very  long  in  contact  -vnth  the  objects.  Evaporation  is  prevented 
by  leaving  the  preparation  in  a  damp  chamber.  Moist  chambers  are 
made  by  means  of  a  porcelain  plate  and  a  small  glass  lid,  of  9  cm. 
diameter  at  the  least.^  Poiu"  water  to  the  height  of  2  cm.  into  the  plate, 
then  place  in  the  middle  a  small  glass  basin,  or  a  cork  plate  standing  on 
four  wooden  feet.  The  slide,  along  Avith  the  preparation,  is  placed  on 
this,  and  the  whole  is  covered  with  the  glass  lid,  the  free  edge  of  which 
is  immersed  in  water. 

12.  Preservation  of  Preparations. — Finished  preparations  must  immedi- 
ately be  labelled.  Do  not  employ  gummed  paper  tickets,  but  those 
of  pasteboard  1-2  mm.  thick,  which  are  fixed  on  the  slide  by  means 
of  the  cement  called  water-glass.-  Special  boxes  for  holding  specimens 
are  thus  superfluous.  The  slides  may  be  placed  over  each  other  Avithout 
pressiure  on  the  preparations.  The  labels  should  be  as  large  as  possible 
(2  cm.  broad  in  the  case  of  slides  of  the  English  size),  and  they  shoidd 
have  recorded  on  them  the  name  of  the  animal,  the  organ,  and,  where 
possible,  a  short  indication  of  the  method.  Use  boxes  or  cabinets  which 
allow  the  slides  to  lie  flat,  not  those  in  which  they  stand  on  their  sides. 

Chap.  VI. —MICROTOMES  AND  SERIAL  SECTION  CUTTING. 

A  microtome  is  an  instrument  by  which  extremely  thin  sections  of 
organs  and  of  tissues  may  be  cut.  There  are  many  varieties  of  such 
instruments,  and  most  of  them  have  certain  points  of  excellence  that 
commend  them  to  their  inventors,  or  to  those  who  acquire  dexterity  in 
their  use.  I  shall  onh'  refer  to  those  of  which  I  have  had  special 
experience.  There  are  essentially  five  methods  of  imparting  to  tissues 
the  proper  consistence  for  section  cutting  by  means  of  microtomes  : 
(1)  embedding  the  tissue  or  organ  in  parafiin  or  in  a  mixture  of 
white  wax  and  parafiin  ;  (2)  infiltrating  the  tissue  Avith  gum  and 
then  freezing  it  by  the  application  of  freezing  mixtures ;  (3)  freezing 
the  tissue  directlj^,  and  often  in  the  fresh  state,  by  the  use  of  ether 
Avhich,  by  its  evaporation,  produces  the  requisite  degree  of  cold ;. 
(4)  infiltrating  the  tissue  A^th  paraffin  dissolved  in  chloroform  or 
other  soh^ent ;  and  (5)  holding  the  hardened  tissue  firmly  by  means 
of  celloidin  or  other  substance  capable  of  giA^ng  it  sviflicient  resistance 
to  the  pressure  of  the  knife. 

^  A  pot,  a  larger  preparation  glass,  etc.,  serve  the  same  purpose. 
^  It  is  a  liquid  of  the  Adscidity  of  syrup,  to  be  had  at  all  druggists,  and  must  be- 
preserved  in  a  well-stoppered  vessel. 


MICROTOMES  AND  SERIAL  SECTION  CUTTING.         279 

1st  Method. — Paraffin"  and  Wax  Embedding, 

The  microtome  used  in  this  method  consisted  of  a  strong  brass 
cylinder  fixed  into  a  horizontal  brass  plate  having  a  smooth  upper 
surface.  The  bottom  of  the  cylinder  consisted  of  a  flat  plate  exactly 
fitting  the  cylinder,  and  attached  underneath  to  a  thick  screw  having  a 
very  fine  thread.  A  well  about  30  mm.  in  depth,  and  45  mm.  in 
diameter,  was  thus  formed,  the  bottom  of  which  was  moved  upwards  by 
a  slight  turn  of  the  screw.  The  tissue,  previously  hardened,  was 
immersed  in  melted  spermaceti,  and  then  in  a  mixture  of  melted  white 
wax  and  paraffin,  or  in  paraffin  alone.  When  the  mass  became  solid,  by 
turning  the  screw  it  was  pushed  upwards,  and  a  section  was  made  by 
pressing  a  razor  or  broad  knife  over  the  surface  of  the  broad  and  smooth 
plate,  in  the  centre  of  which  the  well  opened,  the  tissue  and  razor  being 
kept  moist  with  alcohol.  This  method  had  many  disadvantages,  as,  for 
instance,  the  shrinkage  of  the  tissue  from  the  paraffin,  so  that  it  became 
loose ;  but  it  did  good  service  in  its  day,  especially  in  the  hands  of  such 
a  man  as  the  late  Mr.  A.  B.  Stirling,  assistant  curator  of  the  Anatomical 


Fig.  129. — Rutherford's  Microtome,  arranged  for  freezing  with  ice  and  salt. 


Museum  of  the  University  of  Edinburgh,  who  prepared  histological 
specimens  with  great  skill  and  success.  It  is  now  almost  entirely 
abandoned. 


280  THE  PHYSIOLOGY  OF  THE  TISSUES. 

2nd  Method.— The  Ice  Freezing  Microtome  of  Professor  Rutherford 
AND  Allied  Instruments. 

In  1871,  Professor  Eutherford/  of  the  University  of  Edinburgh, 
invented  and  described  this  instrument,  and  it  is  not  too  much  to  say 
that  it  revolutionized  the  teaching  of  histology  in  this  country.  By 
means  of  it,  400  or  500  thin  sections  can  be  cut  in  the  course  of  an  hour. 
This  has  made  it  invaluable  in  the  teaching  of  large  classes  of  students. 
Its  simplest  form  is  seen  in  Fig.  129.  It  consists  of  a  stage  or  plate  B, 
in  the  centre  of  which  is  a  Avell  of  considerable  depth,  the  bottom  of 
which  is  movable  by  the  screw  D  having  a  fine  thread.  An  indicator 
i^  is  a  little  spring  having  a  small  point  on  the  inner  aspect  of  its  lower 
end  which,  by  sliding  with  a  turn  of  the  screw  into  the  small  holes, 
serves  to  make  the  turns  of  the  screw  equal  in  amount  and  consequently 
secvues  sections  of  uniform  thickness.  Surrounding  the  well  is  the  ice 
box  C,  having  a  tube  H  for  the  escape  of  water  when  the  ice  melts.  The 
bit  of  hardened  tissue  is  immersed  in  a  strong  solution  of  gum  arabic 
(■with  a  few  drops  of  a  solution  of  carbolic  acid  added  to  prevent  the 
growth  of  fungi  in  the  gum)  for  several  days,  so  that  the  gum  may 
thoroughly  soak  through  it.  Some  strong  gum  solution  is  poured  into 
the  bottom  of  the  well,  finely  pounded  ice  and  salt  are  placed  in  layers 
or  mixed  in  the  freezing  box,  and  when  a  thin  layer  of  ice  has 
formed  round  the  interior  of  the  well,  the  bit  of  tissue  is  placed  in 
position.  A  sufficient  amount  of  gum  solution  is  poured  in  to  fill  the 
well,  the  mouth  of  the  well  is  then  closed  with  a  bit  of  gutta-percha 
sheeting,  and  the  whole  apparatus  is  wrapped  in  a  piece  of  thick  flannel 
cloth,  and  left  until  freezing  has  been  thoroughly  established.  The 
wrappings  are  then  removed,  the  bit  of  gutta-percha  taken  from  the 
mouth  of  the  well,  and  Avith  the  knife  held  firmly  so  that  it  glides 
imiformly  on  the  plate  B,  the  mass  of  frozen  gum  at  the  mouth  of  the 
well  is  cut  otf.  The  screw  D  is  then  turned  and  another  section  cut 
until  the  tissue  is  reached.  It  is  then  easy  to  cut  numerous  sections 
quickly  after  each  other,  turning  the  screw  D  to  the  requisite  amount 
betAveen  each  movement  of  the  knife.  When  a  sufficient  number  of 
sections  accumulate  on  the  knife  (or  Avith  each  section  Avhen  great  care 
is  necessary),  they  are  AAdped  off"  the  knife  by  a  camel-hair  brush  into  a 
flat  A^essel  containing  Avater.  The  Avater  dissolves  the  gum.  After 
some  time,  the  sections  are  gently  collected  on  a  straight  needle,  trans- 
ferred to  another  vessel  of  Avater,  and  from  that  into  a  third ;  at  the  end 
of  half  an  hour,  they  are  gathered  in  the  same  Avay  and  transferred  to  a 

^  William  Rutherford,  Journal  of  Anatomy  and  Physiology,  1871  ;    see  also 
The  Lancet,  3rd  January,  1885. 


MICROTOMES  AND  SERIAL  SECTION  CUTTING. 


281 


stoppered  bottle  containing  methylated  spirit,  where  they  may  be  kept 
till  required.  The  most  useful  form  of  knife  is  one  "vvith  a  blade 
200  mm.  in  length  and  30  mm.  in  breadth.  The  back  of  the  knife 
should  be  6  mm.  in  thickness  to  prevent  bending  of  the  blade,  and  the 
side  of  the  blade  which  touches  the  microtome  should  be  ground  flat, 
while  the  upper  surface  is  bevelled. 

Another  form  of  freezing  microtome  is  that  of  Williams,  made  by 
Mr.  Swift  of  London.  It  is  a  circular  box  of  considerable  capacity, 
having  a  metal  pillar  in  the  centre  bearing  on  its  upper  end  a  brass 
plate  30  mm.  in  diameter.  This  box  is  packed  with  powdered  ice  and 
salt,  and  then  the  lid  is  pressed  on,  so  that  the  brass  plate  just  men- 
tioned passes  through  a  hole  in  the  centre  of  the  box  and.  is  on  a  level 
with  the  upper  surface  of  the  lid.  The  upper  surface  of  the  lid  is  made 
of  glass.  The  bit  of  tissue,  soaked  in  gum,  placed  on  the  brass  plate, 
soon  becomes  frozen.  The  sections  are  then  cut  by  a  razor  mounted 
in  a  frame  supported  on  three  fine  screws  passing  through  it,  and  by 
lowering  the  edge  of  the  razor  by  turning  the  screw  placed  beyond  the 
edge  of  the  razor,  and  pushing  the  frame,  carrying  the  razor,  somewhat 


Fig.  130.  -Rutherford's  Microtome,  arranged  for  freezing  with  ether  spray. 

obliquely  across  the  frozen  tissue,  thin  sections  can  be  readily  made. 
This  form  of  freezing  microtome  is  serviceable  for  private  use,  and  for 
cutting  sections  of  small  organs. 


282 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


3rd  Method. — Freezing  by  Means  of  Ether. 

The  production  of  cold  by  the  evaporation  of  ether  has  been  applied 
to  many  microtomes.  The  first  microtome  in  -which  it  Avas  used  was 
the  invention  of  Dr.  Bevan  Lewis  in  1877.^  Dr.  Eutherford^  has 
applied  the  method  to  his  own  microtome,  as  seen  in  Fig.  130,  and  he 
gives  the  following  directions  as  to  its  use — 

"  The  tissue,  which  should  not  be  more  than  a  third  of  an  inch  thick,  is  laid  on 
the  roof  of  a  zinc  box  Z  and  covered  with  gum.  Ether,  ■which  must  be  anhydrous, 
is  then  blown  from  the  bottle  0  by  the  elastic  bellows  y  against  the  lower  surface 
of  the  zinc  plate.  The  condensed  ether  flows  down  through  the  tube  P,  and  is 
collected  in  a  vessel.  The  spray -producing  tubes  T  can  be  readily  pulled  out  of 
the  slot  under  Z  for  examination.  The  tissue  is  soon  frozen,  and  it  remains  frozen 
for  about  five  minutes  in  a  cold  room  without  any  further  production  of  spray." 

A  very  convenient  form  of  microtome  in  which  ether  spray  is  used  as 
the  freezing  agent  is  that  invented  by  Professor  Charles  S.  Roy,  shoAvn 
in  Fig.  131.  "With  this  instrument,  the  consumption  of  ether  is  small, 
and  the  mechanism  works  Anth  a;reat  smoothness. 


Fig.  131. — Roy's  Microtome,  arranged  for  ether  spray,  as  made  by  the  Cambridge 
Scientific  Instrument  Company. 


4th  Method. — Ixfiltkatiox  with  Paraffin. 

The  principle  of  this  method  is  to  infiltrate  the  tissue  "nath  paraffin, 
so  that  the  minute  cellular  elements  may  be  so  supported  as  to  remain  in 
their  natural  position  even  when  they  have  been  cut  in  section.     One  of 

^  Journal  of  Anatomy  and  Physiology,  \%11,  vol.  xi. 
-  Lancet,  Jan.  3,  1885. 


MICROTOMES  AND  SERIAL  SECTION  CUTTING.         283 

the  simplest  methods  is  the  folloT^ang — The  bits  of  tissue  to  be  em- 
bedded, after  having  been  fixed  and  hardened  according  to  any  of  the 
common  methods,  are  thoroughly  dehydrated  with  absolute  alcohol. 
On  a  suitable  water  bath,  the  temperature  of  which  can  be  kept  uni- 
form by  a  mercurial  regulator  governing  the  gas  flame  underneath,  the 
student  should  have  a  few  shallow  vessels,  each  capable  of  holding 
40  CO.  of  fluid.  Chloroform.,  to  which  a  little  sulphimc  ether  has  been 
added,  is  poured  into  one  of  these,  and  one  or  two  bits  of  tissue  are 
transferred  from  the  absolute  alcohol  to  the  chloroform.  This  is  then 
gradually  heated  to  the  melting  point  of  the  paraffin  employed.  Two 
kinds  of  paraffin  should  be  at  hand,  one  melting  at  50°  C,  and  the 
other  at  .36°  C,  and  paraffin  masses  having  difl"erent  melting  points  can 
be  readily  made  by  mixing  these  in  various  proportions.  Suppose  the 
temperature  of  the  water  bath  is  regulated  to  stand  at  38°  C,  then 
pieces  of  paraffin  are  by  degrees  added  to  the  chloroform,  until  the 
bubbles  at  first  given  off  cease  to  appear,  indicating  that  the  paraffin 
dissolved  in  chloroform  has  thoroughly  penetrated  the  object.  In  this 
gradual  infiltration  there  is  scarcely  any  shrinkage.  The  paraffin  is- 
kept  at  its  melting  point  for  some  time,  so  that  the  chloroform  is  com- 
pletely driven  ofi".  The  mass  is  allowed  to  cool,  and  then  sections  may 
be  cut  in  the  dry  condition,  either  with  a  razor  or  by  means  of  a  suit- 


FiG.  132. — Microtome  for  Cutting  Objects  in  ParafBn. 

able  microtome.     The  sections  are  j^laced  on  a  slide,  and  the  paraffin 
is  dissolved  by  pouring    over  the  slide  a   little   turpentine,    benziii. 


284 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


naphtha,  or  x3"lol.  The  section  may  then  be  stained,  and  ultimately 
mounted  in  Canada  balsam  or  dammar  according  to  the  usual  methods. 

Various  forms  of  microtomes  arc  now  employed  for  cutting  sections 
thus  infiltrated  with  paraffin.  One  of  the  most  convenient  of  these  is 
shown  in  Fig.  132. 

The  paraffin  block  is  held  firmly  by  the  clip  D,  and  the  knife  L  is 
moved  by  the  block  K,  somewhat  like  a  carpenter's  plane,  cutting  a 
thin  section  at  each  stroke.  With  each  section,  the  paraffin  block  is 
graduall}'  raised  to  an  extent  varying  according  to  the  required  thick- 
ness of  the  section.  This  is  done  by  pushing  the  block  E  along  the 
inclined  plane  C.  In  other  microtomes,  the  paraffin  block  is  raised 
automatically  by  the  same  movement  as  determines  the  horizontal 
movement  of  the  knife,  and  thus  a  series  of  sections  may  be  cut  in 


quick  succession. 
133 


A  microtome  of  this  construction  is  shown  in  Fig. 


Fig.  133. — Bivet's  Miorotome,  as  modified  by  Reichert. 

In  this  instrument,  the  clip  d  holding  the  paraffin  block  is  moved 
.slightly  upwards  by  means  of  the  toothed  wheel  Z  with  each  horizontal 


MICROTOMES  AND  SERIAL  SECTION  CUTTING. 


285 


movement  of  the  knife  M,  and  there  are  arrangements  by  which  the 
amount  of  upward  movement,  and  consequently  the  thickness  of  the 
section,  may  be  determined. 

For  certain  kinds  of  work,  such  as  cutting  sections  of  embryos  or 
sections  of  particular  parts  of  the  brain  and  spinal  cord,  it  is  often 
important  to  secure  a  consecutive  series  of  sections,  so  that  a  number 
may  be  mounted  on  one  slide  for  comparative  examination.  Various 
contrivances  have  been  designed  to  secure  this  end.  The  most  service- 
able and  simplest  of  these  is  shown  in  Fig.  134. 


Fh3.  134. — The  Rocking  Microtome  of  the  Cambridge  Scientific  Instrument  Company. 

The  pai^ffin  block  is  fixed  to  the  end  of  the  horizontal  bar.  This 
bar  moves  in  a  V-shaped  pivot  on  another  rectangular  bar  placed 
underneath,  which  also  moves  on  a  V-shaped  pivot.  A  glance  at  the 
diagram  shows  that  the  rectangular  bar  is  connected  with  a  screw 
bearing  a  disk  having  a  toothed  edge,  whilst  a  cord  is  attached  to  the 
end  of  the  upper  bar  and  passes  round  a  pulley  connected  with  the 
knobbed  arm  seen  at  the  end  of  the  instrument.  When  we  move  this 
knobbed  arm,  the  toothed  disk  is  pushed  round  a  little  by  a  small 
catch,  the  horizontal  rectangular  bar  is  slightly  raised,  and  the  upper 
bar  is  also  moved  so  as  to  bring  the  paraffin  block  down  on  the  edge  of 
the  razor. 

"  The  distance  between  the  centres  of  the  two  pivoted  systems  is  1  inch,  and 
the  distance  of  the  screw  from  the  fixed  rod  is  6^  inches.  The  thread  of  the  screw 
is  25  to  the  inch ;  it  follows  that  if  the  screw  is  turned  once  round,  the  object  to  be 
cut  will  be  moved  forward  by  tjV  of  k  or  xi^  inch.     The  feed  can  be  varied  from 


286  THE  PHYSIOLOGY  OF  THE  TISSUES. 

0  to  /v  of  a  turn,  hence  the  thickness  of  the  sections  cut  can  be  varied  from  a 
minimum,  depending  on  the  sharpness  of  the  I'azor,  to  a  maximum  of  /w  of  7,^  of 
<u»  oi"  1  oVo  of  ^  turn.  The  practical  minimum  thickness  is  ^ottttu  o^  '•'"  iiich  a-P- 
proximately.  The  value  of  the  teeth  on  the  milled  disk  are  as  follows — 1  tooth  = 
TOTOTf  of  an  inch  ;  2  teeth  =  ■^■aiiv-u  ;  4  teeth  =  Tirtrou  5  8  teeth  =  -juutt  ;  and  16 
teeth  =  irsuD  of  an  inch." 

To  use  this  instrument  effectivch'  requires  careful  attention  to  details, 
but  when  this  is  given,  its  performance  is  very  satisfactory.  The  object 
is  embedded  in  paraffin.  The  block  is  then  cemented  to  the  paraffin 
contained  in  the  socket  of  the  microtome,  its  surflice  being  melted  with 
ii  heated  knife.  The  sides  of  the  block  must  now  l:)e  cut  so  that  the 
opposite  sides  are  parallel.  The  block  is  then  dipped  into  melted  soft 
[)araffin,  that  is  into  paraffin  having  a  low  melting  point,  so  that  it  is 
coated  with  a  layer  of  this  soft  paraffin.  It  is  again  squared  up  and  its 
opposite  sides  made  parallel,  the  coating  of  two  of  the  opposite  sides 
being  removed.  The  socket  carrying  the  block  is  now  placed  on  the 
microtome,  care  being  taken  that  the  sides  coated  A^ath  soft  paraffin 
are  above  and  below,  so  that  the  lower  coated  side  shall  first  come  into 
contact  with  the  edge  of  the  razor.  Then,  as  we  work  the  microtome,  the 
fsections  come  off  like  a  ribbon,  as  shown  in  the  figure.  To  secure  a 
good  chain,  the  follo^Adng  points  must  be  noticed — 1st,  The  paraffin  must 
be  of  a  melting  point  having  a  certain  relation  to  the  temperature  of  the 
laboratory.  Small  sections  can  always  be  made  to  "  chain"  when  cut  from 
ii  good  paraffin  of  45°  C.  melting  point,  in  a  room  the  temperature  of 
which  is  16°  or  17°  C.  If  at  22°  C,  then  the  paraffin  should  melt  about 
48°  C.  2nd,  The  razor  should  be  carefully  set  square.  3rd,  The  block 
of  paraffin  should  be  pared  do^^Ti  very  close  to  the  object,  and  should  be 
cut  so  as  to  present  a  straight  edge  to  the  knife  edge,  and  the  opposite 
edge  should  be  parallel  to  this.  4th,  The  sections  should  be  cut  rapidly, 
by  swiit,  sudden  strokes. 

To  mount  sections  thus  cut  in  ribbons  various  methods  may  be 
employed. 

(a)  GiesbricJit's  method.  Make  a  moderately  strong  solution  of  brown  shellac  in 
absolute  alcohol  ;  filter  ;  warm  the  slides  to  remove  all  mr)isture,  and  spread  over 
them  by  a  glass  rod  a  thin  layer  of  shellac.  Allow  the  slides  to  dry.  Moisten  the 
shellac  siirface  with  a  little  creasote,  and  then  lay  the  ribbons  on  the  sticky  surface 
thus  produced.  Heat  the  slide  on  a  water  bath  at  the  melting  point  of  paraffin 
for  a  quarter  of  an  hour  ;  the  paraffin  melts,  and  the  sections  come  thus  into  con- 
tact with  the  shellac.  The  creasote  also  evaporates,  and  when  the  slide  cools,  the 
sections  will  be  adherent  to  the  shellac.  Then  di'op  turpentine  on  the  sections  to 
dissolve  off  the  paraffin,  and  lastly  mount  in  Canada  balsam. 

(&)  Garde's  method.  Moisten  the  slide  with  alcohol,  and  arrange  the  ribbons  on 
it  with  a  camel  hair  pencil ;  heat  the  slide  slightly  so  as  to  cause  the  section  to 
stick  to  the  glass  ;  put  on  a  cover-glass,  and  run  in  below  it  a  solution  of  equal 


MICROTOMES  AND  SERIAL  SECTION  CUTTING.         287 

parts  of  Canada  balsam  and  xylol.  If  the  sections  are  thick,  the  process  of 
adding  a  drop  of  pure  xylol  may  have  to  be  repeated  until  all  the  paraffin  has  been 
dissolved. 

(c)  A  mixture  of  equal  parts  of  egg-albumin  and  water  may  be  employed,  to 
which  a  little  glycerine  should  be  added  to  prevent  too  rapid  drying.  This  is 
spread  in  a  thin  layer  upon  the  glass,  and  when  the  section  is  laid  upon  the  slide 
it  is  advisable  to  breathe  upon  it,  thus  rendering  the  albumin  moister,  and  slightly 
heating  the  paraffin  with  which  the  tissue  is  impregnated,  and  so  making  it  more 
pliable  and  adhesive. 

[d)  A  mixture  of  one  part  of  collodion  with  four  parts  of  oil  of  cloves  may  be 
employed. 

5th  Method. — Cutting  in  Celloidix, 

Celloidin  is  pure  pyroxylin,  and  is  sold  in  the  form  of  tablets  of  a 
tough  gelatinous  consistency.  It  is  soluble  in  ether  and  alcohol.  Cut 
the  celloidin  into  small  bits,  and  dissolve  in  equal  parts  of  absolute 
alcohol  and  ether.  Soak  the  tissue  to  be  cut  in  absolute  alcohol,  transfer 
it  to  the  celloidin,  and  leave  it  there  for  two  or  three  weeks.  When 
thoroughly  permeated  mth  celloidin,  the  preparations  are  transferred 
to  a  paper  tray,  and  are  surrounded  with  celloidin,  until  a  skin  forms 
round  the  mass,  and  then  the  mass  is  thrown  into  a  consideraljle  quantity 
of  alcohol  of  82°,  in  which  it  may  be  kept  for  any  length  of  time. 
After  twenty-four  hours'  immersion  in  this  alcohol,  the  sections  may 
be  cut  in  alcohol.  Gudden's  microtome  should  be  used.  This  consists 
of  a  cylindrical  well  mth  movable  bottom  and  horizontal  plate,  as  in 
Rutherford's  microtome,  but  fixed  in  the  centre  of  an  iron  trough,  so 
that  the  surface  of  the  tissue  may  be  bathed  in  methylated  spirit 
while  the  sections  are  being  cut.  The  sections  may  be  cleared  in 
glycerine,  which  makes  celloidin  perfectly  transparent,  or  they  may 
be  mounted  in  Canada  balsam  by  the  following  process  :  dehydrate  with 
95  per  cent,  alcohol,  clear  with  oil  of  bergamot,  and  mount  in  balsam.  Oil 
of  cloves  cannot  be  used  as  it  dissolves  celloidin.  Many  other  methods 
of  using  celloidin  have  been  devised,  but  the  above  is  simple  and  con- 
venient. To  mount  sections  that  have  been  cut  in  series  in  celloidin, 
the  following  is  the  method  recommended  by  Minot :  the  sections  are 
arranged  on  a  slide  in  95  per  cent,  alcohol ;  the  alcohol  is  poured  oflF, 
and  a  drop  of  alcoholic  shellac  (made  by  dissolving  10  grms.  of  bleached 
shellac  in  100  c.c.  of  absolute  alcohol,  and  filtering)  placed  over  each 
section ;  the  slide  is  placed  over  a  water  bath  at  40°  C.  for  five  or  ten 
minutes,  until  dry ;  it  is  then  cleared  up  with  oil  of  cloves,  and  finally 
mounted  in  balsam. 

For  full  details  regarding  histological  methods,  reference  is  made  to  Whitman's 
Methods  of  Research  in  Microscoincal  Anatomy  and  Emhryology ,  Boston,  1885  ;  to 
Arthur  Bolles  Lee's  Microiomist's  Vade-Mecum,  London,  1885  ;  and  to  Mannel  de 
Technique  Microscopique,  by  Dr.  Paul  Latteux,  Paris,  1887. 


288  THE  PHYSIOLOGY  OF  THE  TISSUES. 

Chap.  VII.— PROTOPLASM  AND  CELLS. 

1.  Protoplasm. — The  general  characters  of  protoplasm  have  already 
been  descriljed  (p.  205).  It  is  a  jelly-like  substance,  colourless,  or 
faintly  yellow,  amorphous,  or  showing  a  network  of  fine  fibres,  or 
having  embedded  in  it  molecules  or  granules.  It  is  difficult  to  observe 
it  in  the  ultimate  structures  of  the  higher  animals,  and  our  knowledge 
of  it  has  been  derived  chiefly  from  observations  on  microscopic  animals 
and  plants.  It  may  be  met  with  in  nature  in  two  conditions — (1)  free, 
or  (2)  in  the  interior  of  cells.  Free  protoplasm  may  occur  in  masses  of 
jelly-like  matter,  called  plasmodies,  as  may  be  seen  in  myxomycetes,  which 
are  the  fungi  found  on  old  leather,  or  on  tan.  Such  masses,  when 
examined  under  the  microscope,  are  granular,  and  show  not  only 
changes  of  form  slowly  occurring,  but  also  currents  flowing  through 
the  jelly-like  matter  in  various  directions.  In  a  state  of  rest,  proto- 
plasm is  alkaline  in  reaction,  but  during  activity  it  becomes  acid.  Thus 
Engelmann  observed  that  granules  of  blue  litmus  became  red  in  the 
bodies  of  small  infusoria.  It  has  been  ascertained  that  these  move- 
ments are  affected  by  external  agents.  Thus,  the  protoplasm  moves 
towards  light ;  heat  quickens  while  cold  retards  the  movements,  and 
extreme  cold  or  extreme  heat  will  arrest  the  movements  altogether ; 
electricity  excites  contraction ;  oxygen,  as  in  atmospheric  air,  is  neces- 
sary for  the  movement,  and  excess  increases  its  activity ;  and  finally, 
the  movements  are  arrested  by  carbonic  acid,  ether,  chloroform,  solu- 
tions of  sulphate  of  quinine,  and  by  other  poisons. 

Another  form  of  free  protoplasm  is  seen  in  the  amoebce  of  stagnant 
pools.  These  consist  of  a  mass  of  protoplasm,  sometimes  homogeneous, 
but  usually  containing  granules.  These  bodies  slowly  change  their 
form,  pushing  out  one  part  of  the  body  in  a  particular  direction  as  a 
perfectly  hyaline  substance,  and  afterwards  slowly  retracting  it.  Some- 
times numerous  processes  are  thus  protruded  simultaneously,  or  one 
after  the  other,  so  as  to  give  the  mass  of  protoplasm  an  irregularly 
stellate  appearance.  By  these  changes  of  form  the  amoeba  moves  from 
place  to  place.  It  may  also  surround  by  these  processes  any  particle 
of  nutrient  matter  Avith  which  it  may  come  into  contact,  and  afterwards 
absorb  it  into  its  substance.  Bodies  exactly  similar  to  the  amoeba,  and 
therefore  called  amcehoicl,  exist  in  the  body,  as,  for  example,  the  colour- 
less corpuscles  of  the  blood  and  connective  tissue  corpuscles. 

Protoplasm  may  also  exist  in  the  interior  of  vegetable  and  animal 
cells.  Thus,  its  movements  may  be  watched  in  the  hairs  of  Trades- 
cantia  (Fig.  135),  of  Urtica,  the  common  nettle,  and  in  the  cells  of 
Chara   and    Vallisneria.      The   existence   of  protoplasm   may   also   be 


PROTOPLASM  AND  CELLS. 


289 


demonstrated  in  many  animal  cells,  sucli  as  in  the  cartilage  cell,  in  the 
pigment  cell  of  the  frog's  skin,  in  the  ovum,  and  in  the  bodies  of 
many  cellvdar  infusoria. 

The  jelly-like  matter  which  forms 
the  organic  basis  of  protoplasm  is 
nitrogenous,  and  is  probably  of  an 
albuminous  nature,  while  the  gran- 
ules consist  of  fats  or  starch.  The 
identity  of  protoplasm  in  animal 
and  vegetable  cells  has  been  as- 
sumed, but  has  never  been  proved. 
Protoplasm  is  permeable  by  water. 
The  molecular  changes  occurring 
in  it  are  very  active.  It  assimilates 
and  excretes,  and  it  absorbs  oxygen 
and  eliminates  carbonic  acid.  So 
far  as  ovcc  present  methods  of  re- 
search carry  us,  the  liberation  of 
energy  in  protoplasm  occurs  under 
the  form  of  movement.  This 
movement  presents  itself  under 
two  aspects— (1)  a  kind  of  lique- 
faction, as  it  has  been  called,  which 
produces  the  optical  appearance  of 
a  current  in  the  mass ;  and  (2)  a 
change  of  form  which,  in  some 
cases,  produces  a  movement  of  pro- 
gression. In  certain  masses  of  pro- 
toplasm there  exist  small  cavities 
filled  with  water,  called  vacuoles, 
the  walls  of  which  frequently  show  rhythmical  contraction. 

Heitzmann,  whose  researches  on  the  structure  of  the  cell  and  of 
nuclei  have  been  already  referred  to,  in  a  recent  communication,^  makes 
the  following  remarkable  statements  regarding  the  nature  of  proto- 
plasm— 

1.  Protoplasm  is  not  stractureless,  but  is  reticulated.  The  nucleus  is  not  solid, 
but  is  also  reticulated,  and  the  intersections  of  reticulations  are  the  nucleoli. 
Protoplasm  is  the  same  substance  as  that  which  forms  the  nucleus  and  reticulum. 
This  reticulum  is  the  real  living  matter ;  it  is  in  constant  motion  ;  all  new  growth 
starts  from  it. 

2.  All  varieties  of  connective  tissue,  myxomatous,  fibrous,  cartilaginous,  bony, 

^  Heitzmaun,  Transactions  of  the  New  Yorh  Academy  of  Medicine,  vol.  iv.  p.  167. 
I.  T 


Fig.  135.— Cells  of  Tradescantia.  A,  fresh 
in  water ;  B,  the  same  ceU  after  strong 
electrical  irritation.  The  irritated  proto- 
plasm assumes  the  forms  of  little  lumps  or 
nodules,  c,  c,  united  by  slender  filaments 
and  also  small  club-shaped  projections,  d. 


290 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


and  the  intercellular  substance,  have  also  a  reticulum  of  living  matter.  In  the 
tissue-elements  (cells),  the  meshes  of  the  reticulum  are  filled  with  liquid,  but  in 
the  meshes  of  the  reticulum  of  the  intercellular  matter  it  is  "glue  yielding." 
Thei'e  are  no  individual  cells  in  a  strict  sense,  as  all  are  united  by  threads  of 
reticulum. 

3.  In  inflammation,  not  only  do  cells  grow  and  proliferate,  but  the  basis-sub- 
stance furnishes  a  considerable  amount  of  inflammatory  elements.  Pus  corpuscles 
are  the  inflammatory  corpuscles  torn  asunder  and  isolated. 

4.  Epithelia  are  also  reticular.  The  cement  substance  joining  epithelial  cells 
is  traversed  by  delicate  conical  offshoots. 

Modes  of  observing  Protoplctsm  and  Cells. — It  is  sometimes  necessary  to  submit 
protoplasm,  cells,  and  living  tissues  to  the  action  of  physical  agents,  such  as  heat 
or  electricity,  or  to  the  action  of  various  gases  and  vapours. 

(1)  Heat  may  be  readily  applied  by  the  use  of  the  arrangement  termed  a  hot 
stage,  of  which  there  are  many  forms.  The  hot  stage  shown  in  Fig.  1.36  is  con- 
venient.    It  consists  of  a  flat  hollow  box,  through  which  a  stream  of  hot  water 


Fig.  136. —Hot  Stage. 


can  be  carried  by  the  entrance  tube,  C,  and  the  exit  tube,  B.  In  this  form  the  hot 
water,  after  issuing  from  B,  is  carried  to  a  small  circular  chamber,  H,  above  the 
objective,  so  as  to  bring  the  latter  to  nearly  the  same  temperature  as  the  stage, 
and  then  the  water  flows  off  by  the  tube,  E.  In  the  centre  of  the  stage  there  is  a 
well.  A,  the  bottom  of  which  is  formed  of  glass.  A  drop  of  the  fluid  containing 
the  living  structure  to  be  submitted  to  the  action  of  heat  is  placed  on  the  centre 
of  a  cover-glass,  and  the  latter  is  then  inverted  over  A.  The  temperature  at 
which  the  living  structure  is  submitted  to  examination  is  ascertained  by  the  ther- 
mometer on  the  left  of  the  stage. 

(2)  Electricity  may  be  applied,  either  in  the  form  of  shocks  or  of  a  continuous 
current  by  the  simple  arrangements  shown  in  Figs.  137  and  13S. 


PROTOPLASM  AND  CELLS. 


291 


Fig.  137. — Arrangement  for  electrical  stimvilation  of  objects 
under  microscopical  examination,  consisting  of  strips  of  tin- 
foil cemented  on  a  glass  slide.  The  object  to  be  examined  is 
placed  on  the  centre  of  the  narrow  strips  that  are  close 
together. 


Fig.  138. — Arrangement  for  electrical  stimulation 
of  objects  under  microscopical  examination.  A, 
triangular  strip  of  tinfoil  cemented  to  glass,  and 
bent  round  the  ends  of  glass  D.  Observe  a 
similar  piece  on  the  other  side.  Object  is  placed 
in  centre  of  circle  between  pointed  ends  of  tin- 
foil. B  and  C,  terminals  from  battery  lying 
between  glass,  D,  and  the  large  slide,  and  touch- 
ing the  tinfoil  bent  round  ends  of  D. 


(3)  Gases  and  Vapours.— These  may  be  conducted  into  a  small  chamber  con- 
taining the  living  tissue  by  means  of  simple  arrangements,  such  as  are  shown  in 
Figs.  139  and  140. 


Fig.  139. — Arrangement  for  obsei^ing  action  of  gases  and  vapours  on  living  tissues.  C, 
glass  cylinder  cemented  to  slide  ;  on  the  under  surface  of  the  cover,  the  object  may  be 
placed.     A  and  B,  entrance  and  exit  tubes. 


292 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


Fig.  140.— Arrangement  for  observing  action  of  gases  and  vapoUrs.  A  A,  metal  ring 
resting  on  slide  and  covered  by  square  cover-glass ;  B,  C,  entrance  and  exit  tubes, 
passing  into  chamber  D. 


For  the  examination  of  tissues  or  fluids  in  a 
chamber,  the  atmosphere  of  which  contains  so 
much  moisture  as  to  prevent  evaporation  from,  and 
drying  of,  the  tissue  or  fluid,  the  arrangement 
termed  Von  Recklinghausen's  moi>it  chaynber  is  very 
convenient.  It  is  shown  in  Fig.  141.  The  cham- 
ber consists  of  a  cylindrical  glass,  A,  narrow  at 
the  top,  cemented  to  the  slide,  B  C.  Into  the 
upper  and  narrow  end  of  the  glass  chamber,  the 
lower  end  of  the  body  of  the  microscope,  bearing 
the  objective,  passes,  and  the  glass  and  end  of  the 
microscope  are  bound  together  by  india-rubber 
sheeting,  as  shown  in  the  figure. 


Fig.  141. — Von  Recklinghausen's 
Moist  Chamber. 


2.  Cells. — Many  tissues  consist  almost  exclusively  of  one  species  of 
cell.  Such  are  termed  simple  tissues  to  distinguish  them  from  other 
tissues,  in  the  structure  of  which  various  species  of  cells  are  concerned ; 
in  the  latter  case,  the  term  complex  tissues  is  employed.  By  the  term 
simple  tissue,  epithelial  tissue,  connective  tissue,  muscular  tissue,  and 
nerve  tissue  are  represented.  By  the  term  complex  tissue,  we  desig- 
nate the  structures  resulting  from  the  union  of  various  simple  tissues- 
structures  which  receive  the  more  appropriate  term  of  Organs.  It 
must  also  be  borne  in  mind  that  in  point  of  fact  the  simplest  tissues 
of  all  are  composed  of  several  tissues.  For  example,  muscular  tissue 
consists  of  muscular  cells,  of  connective  tissue,  and  of  vessels  and  nerves, 
which,  in  their  turn,  are  themselves  composed  of  different  tissues. 

(1)  General  Themj  of  Cells.— The  collective  organs  of  the  animal  body 
consist  of  cells  and  of  substances  formed  from  cells  as,  for  example,  the 
intercellular  substances.  By  the  term  cell  is  understood  a  morphologi- 
cal element  limited  in  space,  which  is,  under  certain  conditions,  in  a 
position  to  receive  nourishment,  to  grow  and  to  propagate  itself  By 
reason  of  these  powers,  the  cell  may  bear  the  designation  of  an 
Elementary  Organism. 


PROTOPLASM  AND  CELLS.  293 

The  morphological  properties  of  cells  have  already  been  described, 
but  a  brief  recapitulation  may  here  be  given.  The  essential  constit- 
uents of  a  cell  are — (1)  protoplasm,  a  fine  granular,  yielding  substance, 
which,  insoluble  in  water,  is  easily  capable  of  a  flowing  motion,  and 
•consists  principally  of  albuminous  bodies,  water  and  salts ;  and  (2)  the 
nucleus,  an  almost  clear,  sharply  defined  vesicle,  which  is  confined 
within  a  thin  membrane,  the  nuclear  membrane,  and  contains  a  network 
of  minute  threads  of  diflferent  degrees  of  fineness.  Thickenings  of  these 
fibres  are  termed  nuclear  corpuscles  or  nucleoli.  In  the  meshes  of  the 
reticulum  there  exists  fluid,  viz.,  the  nuclear  fluid.  The  reticulum  and 
the  nucleoli  are  readily  coloured  by  means  of  many  dye  stufis,  on 
account  of  which  the  substance  composing  them  is  termed  chromatin. 
The  nuclear  fluid  is  incapable  of  taking  on  colour.  The  nuclei  also 
consist  of  albuminous  bodies,  of  water  and  salts.  To  these  there  is  also 
added  a  substance  peculiar  to  nuclei,  nuclein.  The  majority  of  cells 
contain  one  nucleus  ;  only  isolated  cells  possess  several  nuclei  (giant 
•cells).  Cells  without  nuclei  (the  horny  cells  of  the  epidermis,  the 
coloured  blood  corpuscles  of  mammals)  originally  possess  one  nucleus, 
l)ut  lose  it  in  the  process  of  development.  As  unessential  constituents 
of  cells  may  be  mentioned — the  cell  membrane  or  cell  wall,  which  is 
wanting  in  many  cells,  and  in  cases  in  which  it  is  present,  it  is  either 
the  firm  peripheral  layer  of  protoplasm  or  it  appears  as  a  thin,  almost 
structureless,  cuticle  ;  as  constituents  of  secondary  importance,  may 
also  be  classed  minute  grains  of  pigment  and  drops  of  fat,  of  watery 
and  mucous  moisture,  which  occur  in  the  protoplasm  of  individual 
cells.  In  A'ery  young  cells  sometimes  the  cell  wall  possesses  a 
certain  amount  of  elasticity  so  as  to  mould  itself  upon  the  surface, 
when  the  included  protoplasm  changes  its  form,  but  at  other  times 
it  is  stiff  and  rigid.  It  is  permeable  by  water  and  by  aqueous 
solutions  of  acids,  bases,  and  salts,  but  it  will  not  permit  the  pas- 
sage of  oils  and  fatty  substances.  Its  chemical  constitution  is  not 
the  same  in  the  animal  and  vegetable  kingdom.  In  plants  it  is 
formed  of  cellulose,  a  non-nitrogenous  substance ;  but  in  animals  it 
is  always  nitrogenous.  It  contributes  only  to  the  life  of  the  cell  by  its 
physical  property  of  permitting  the  passage  of  fluid  by  osmosis,  but  it 
is  not  connected  in  any  other  way  with  the  vital  phenomena  of  the  cell. 
Occasionally,  it  may  become  hard  and  impermeable  by  the  deposit  in  it 
of  calcareous  salts  and  of  silica. 

(2)  Form  of  Cells. — The  form  of  cells  is  very  various.  It  may  be: 
(1)  Spherical,  which  is  the  form  of  all  cells  in  the  embryonic  period,  but 
in  the  case  of  the  adult,  the  white  blood  corpuscles,  for  example,  are 
spherical ;  (2)  Disc-shaped,  as,  for  example,  the  coloured  blood  corpuscles; 


294  THE  PHYSIOLOGY  OF  THE  TISSUES. 

(3)  Polyhedral,  the  cells  of  the  liver;  (4)  C3'liiidrical,  the  epithelial  cells 
of  the  small  intestine ;  (5)  Cubical,  the  epithelial  cells  of  the  capsule  of 
the  lens;  (6)  Flattened,  for  example,  endothelial  cells;  (7)  Spindle- 
shaped,  such  as  many  connective  tissue  cells  ;  (8)  draA\Ti  out  into  long 
fibres,  for  example,  smooth  muscular  fibres ;  and  (9)  those  which  are  star- 
shaped,  such  as  many  ganglion  cells.  The  form  of  the  nucleus  is  in  most 
cases  adapted  to  the  form  of  the  cells.  It  assumes  an  oval  shape  Avhen 
surrounded  by  cylindrical,  spindle-shaped,  and  star-shaped  cells ;  it  is 
spherical  when  siurrounded  by  round  and  cubical  cells.  Irregularly 
shaped  or  polj^moi'phic  nuclei  occur  in  the  case  of  leucocytes  (white 
blood  corpuscles)  and  giant  cells. 

The  form  would  appear  to  depend  largely  on  the  amount  and  direction 
of  the  pressure  to  which  the  cell  is  subjected.  The  most  important 
physical  character  of  the  active  cell  is  its  permeability  to  fluids.  If 
ceUs  are  placed  in  distilled  water,  they  swell  out  by  imbibition ;  on  the 
other  hand,  if  placed  in  a  fluid  of  greater  specific  gravity  than  that  of 
their  contents,  they  may  shrivel  and  become  irregular  in  form  by  the 
passage  of  a  portion  of  their  contents  into  the  surrounding  fluid. 

(3)  Size,  of  Cells. — The  size  of  cells  fluctuates  from  microscopically 
small  forms,  4  /a  in  diameter  (certain  coloured  blood  cells),  up  to  bodie.s 
visible  to  the  naked  eye,  such  as  the  ova  of  birds,  amphibia,  etc. 

(4)  Nutrition  of  Cells. — The  nutritional  changes  of  the  cell  consist  of 
assimilation  and  disassimUation.  By  assimilation  the  cell  receives  from 
the  medium  Avhich  surroiuids  it  certain  materials  which  it  converts  into 
its  own  proper  substance,  or  which  it  may  utilize  in  various  ways. 
There  appear  to  be  two  phases  of  the  assimilative  process  :  (1)  one  in 
which  the  cell  transforms  the  matter  which  it  receives,  and  the  other  (2) 
in  which  the  substances  transformed  become  an  integral  part  of  the  cell. 
The  first  phase  is  Avell  marked  in  the  life  of  the  vegetable  cell,  but  is  not 
so  distinct  in  the  animal  cell,  which  in  a  manner  lives  upon  materials 
previously  formed  by  the  plant;  the  second  phase,  on  the  contrary, 
exists  to  an  equal  extent  both  in  the  animal  and  vegetable  cell.  The 
assimilating  process  in  the  K-vdng  portion  of  the  cell  has  received  the  name 
of  metabolism,  while  the  chemical  change  by  Avhich  matters  taken  up  by 
the  cell  may  be  converted  into  other  matters  is  called  metastasis.  Thus 
a  cell  may,  by  metabolic  processes,  convert  dead  matter  into  living- 
matter  like  itself,  or  it  may,  by  metastatic  processes,  com^ert  dead 
matter  into  another  form.  The  disassimilative  processes  occurring  in  the 
living  ceU  consist  of  chemical  changes  in  the  substance  of  the  cell  itself, 
or  of  materials  in  contact  with  the  cell.  Disassimilative  processes  con- 
stitute a  marked  feature  in  the  life  of  animal  cells.  Certain  cells  have 
the  property  of  separating  or  forming  a  special  kind  of  material.     Thus 


PROTOPLASM  AND  CELLS.  295 

some  cells  form  fatty  matter,  others  pigments,  and  a  third,  one  or  other 
of  the  substances  existing  in  bile.  This  power  has  been  termed  elective 
affinity.  Certain  materials  are  separated  from  cells  by  a  process  which 
may  be  termed  cellular  excretion,  and  other  cells  may  store  up  certain 
materials  in  their  interior,  a  process  called  cellular  secretion. 

(5)  Irritability  of  Cells. — By  this  term  we  mean  the  aptitude  which  a 
cell  has  of  responding  to  a  determinate  stimulus,  and  which  is  an 
important  condition  of  vital  phenomena.  The  stimulus  may  be 
mechanical,  chemical,  physical,  or  vital.  The  same  kind  of  stimulus 
may  produce  different  results,  varying  according  to  the  nature  of  the 
cell.  Thus  the  response  to  a  stimulus  of  a  muscular  cell  is  contraction; 
of  a  glandular  cell,  secretion ;  of  an  epithelial  or  connective  tissue  cell, 
cell  multiplication ;  and  of  a  nerve  cell,  some  kind  of  activity  resulting 
in  sensation,  perception,  volition,  or  one  or  other  of  the  stages  of 
intellectual  acts.  It  may  be  laid  down  as  an  axiom  that  no  activity  in 
a  cell  ever  occurs  without  an  antecedent  stimulus. 

(6)  Movement  of  Cells. — One  of  the  most  evident  phenomena  in  the  life 
history  of  many  cells  is  movement.  This  is  seen  in  the  form  of  amoeboid 
motion,  of  ciliary  motion,  and  in  the  contractions  of  certain  fibres  (mus- 
cular fibres).  Amoeboid  motion  is  the  most  important.  Widely  spread, 
it  has  been  observed  in  nearly  all  kinds  of  animal  cells.  In  marked 
cases,  in  that  of  leucocytes  (white  blood  corpuscles)  for  example,  the 
protoplasm  of  the  cells  stretches  out  finer  or  coarser  extensions,  which 
sub-divide,  again  flow  together,  and  produce  in  this  manner  many  diverse 
forms.  The  extensions  (pseudopodia)  may  be  again  retracted,  or  they 
fix  themselves  to  some  particular  spot  and  draw  to  themselves  in  some 
measure  the  remaining  part  of  the  body  of  the  cell.  Thus  there  are 
changes  of  situation,  which  are  termed  the  migrations  of  the  cells,  and 
which  play  an  important  part  in  the  economy  of  the  animal  frame. 
The  expansions  of  the  protoplasmic  body  may  flow  round  grains  or  small 
cells,  and  thus  enclose  them  within  the  body  of  the  cell  (Fig.  155). 
Amoeboid  motions  in  the  case  of      ^, 

warm-blooded  animals   are  very  """^         i        2  2/2 

slow,  and  can  only  be  detected  by 
careful  observation  with  the  aid  of 
the  hot  stage.  They  may  be  readily 
studied  by  watching  the  move- 
ments of  the  leucocytes,  or  white 
blood  corpuscles,  in  the  blood  oi    3%        s         g  s         m  Minutes. 

amphibia    (frog    or    newt),    when  Pig.  142.— Leucocytes  in  frost's  wood.     X560d. 

IP  i     1    •  Changes  of  form  observed  during  ten  minutes. 

such   forms  as  are  represented   m  0,  beginning  of  observation,  then  at  intervals 

TTi-        -\  A  n  11  1  of  i,    1,    2   minutes,   etc.      (Method    No.    11, 

Fig.  142  may  be  observed.  Appendix.) 


296  THE  PHYSIOLOGY  OF  THE  TISSUES. 

A  remarkable  example  of  movement  in  cells  was  described  by  Lister  as  occurring 
in  the  pigment  cells  of  the  skin  of  the  frog.  These  cells  contain  fine  molecules  of 
a  black  pigment.  Under  the  influence  of  light,  these  molecules  collect  towards  the 
central  part  of  the  cell,  leaving  light-coloured  areas  around  each  dark  mass  of 
molecules.  In  these  circumstances,  the  frog's  skin,  to  the  naked  eye,  is  pale.  In 
darkness,  the  molecules  pass  out  towai'ds  the  circumference  of  the  cells,  and  con- 
sequently the  skin  of  a  frog,  from  which  light  has  been  excluded  for  some  time, 
appears  dark,  if  examined  before  light  has  had  time  again  to  make  it  pale. 
VonAVittich  found  in  the  tree-frog  {Hyla  arhorca)  that  contraction  of  the  pigment 
cells  followed  mechanical  irritation  of  the  skin  or  irritation  by  electricity  or  bj'' 
turpentine,  and  that  the  same  result  followed  irritation  of  the  motor  nerves 
passing  to  the  limb.  Undoubtedly,  in  this  case,  the  movement  of  the  protoplasm 
in  the  cell  is  due  to  a  reflex  nervous  influence,  as  division  of  the  nerves  passing  to 
the  limb  causes  the  skin  to  appear  dark,  and  the  darkness  does  not  then  disappear 
on  exposure  to  bright  light.  The  motor  impulse  passing  to  the  pigment  cells  must 
therefore  travel  from  the  nerve  centres  along  the  ordinary  motor  nerve  trunks. 
On  the  other  hand,  the  sensory  impulses  which  affect  the  centres  so  as  to  cause  the 
motor  impulses  to  pass  out,  travel  from  the  retina  along  the  optic  nerves  to  the 
nerve  centres,  as  it  has  been  ascertained  that,  after  blindness,  exposure  to  light  no 
longer  causes  the  skin  to  become  pale.  Thus,  whether  the  play  of  light  and  shade 
in  the  skin  of  such  amphibians  is  due  to  a  streaming  of  the  molecules  to  and  from 
the  centre  of  the  cell,  or  to  a  contraction  of  the  protoplasm  in  which  the  molecules 
are  embedded, [there  is  here  an  automatic  mechanism  by  which  the  tint  of  the 
animal's  skin  can  be  brought  into  harmony  with  that  of  its  surroundings,  a  fact  of 
great  general  significance. 

There  is  yet  another  phenomenon  of  movement 
which  is  observable  not  only  in  the  living  but  also 
in  the  dead  cell.  It  is  the  so-called  molecular  motion 
or  Bro"\^Tiian  movement,  an  oscillation  of  the 
minutest  granules  in  the  cell,  which  is  the 
result  of  fluid  molecular  currents.     It  is  readily 

Fig.  143.— Drop  of  saliva,    observed  in  salivary  corpuscles  (Fig.  143). 

squamous' epithelial  cells  •        (7)  Fo^-matioii  and  RepwducHon  of  Cells. — A  dis- 

and    b,    salivary    corpus-     ....  .  ..  ,  ,.  ,  -.-, 

cies,     in     which     the   tiuctioii  was  at  One  time  dra^vn  between  two  kinds  oi 

Brownian  movement  may  ,,   „  ,.  •        /-i  \  c  n    p  ,•         /  ,• 

be  observed.  Cell  lormatiou,  VIZ.,  (1)  tree  cell  lormation  [generamo 

cequivoca)  and  (2)  the  origination  of  cells  through 
division  of  pre-existing  cells.  According  to  the  theory  of  free  cell 
formation,  the  cells  were  supposed  to  have  originated  in  soft 
granular  matter  adapted  for  the  purpose,  called  hjtohlastema.  This 
theory  has  been  totally  abandoned ;  we  now  know  only  one  kind  of  cell 
formation,  viz.,  the  formation  of  cells  through  the  division  of  cells  already 
existing.  Omnis  cellula  e  cellula.  In  the  division  of  a  cell,  the  nucleus 
plays  an  imjDortant  part.  The  division  is  efiected,  not  often  in  the 
simple  way  of  the  division,  first  of  the  nucleus,  and  then  of  the 
protoplasm  into  two  equal  parts,  termed  direct  division  or  karyostenosis ; 


PROTOPLASM  AND  CELLS.  297 

but  it  occiirs  as  a  complex  process,  termed  indirect  division  or  karyo- 
kinesis.  This  latter  process  has  already  been  fully  described  at  p.  213. 
As  special  modifications  of  cell  division,  the  so-called  endogenous  cell 
formation  and  the  process  of  budding  furnish  good  examples.  Endog- 
enous cell  formation  is  seen  in  cells  which  possess  a  firm  covering, 
such  as  ova  (Fig.  Ill,  p.  234)  and  in  cartilage.  (See  Cartilage.)  The  pro- 
cess of  division  is  exactly  the  same  as  that  above  described,  with  this 
difference  that  the  daughter  cells,  originating  from  one  cell  (the  mother 
cell)  through  continued  division,  remain  enclosed  within  a  common 
covering.  The  process  of  cell  multiplication  is  termed  gemmation  or 
budding,  when  a  cell  sends  forth  shoots  or  buds  which  gradually  separate 
from  the  parent  and  grow  into  independent  cells.  Young  cells  always 
exhibit  the  character  of  the  mother  cell.  The  development  of  connec- 
tive tissue  cells,  for  example,  from  the  division  of  an  epithelial  cell 
never  occurs. 

(8)  Phenomena  of  Secretion  in  Cells. — This  process  is  manifested  by 
differences  seen  in  the  form  and  contents  of  the  gland  cell  when  it  is  in 
a  state  of  rest  and  when  it  is  in  a  state  of  activity.  In  many,  as,  for  example, 
in  the  cells  of  a  serous  gland,  these  differences  are  shown  in  a  small  bulk 
and  a  dark  appearance  of  the  cells  in  the  state  of  rest,  and  an  increased 
bulk  and  clearer  appearance  in  the  state  in  which  the  process  of  secretion 
is  active.  In  the  case  of  other  gland  cells,  such  as  those  of  mucous 
gland  cells  in  man,  the  formation  of  the  secretion  admits,  on  the  other 
hand,  of  being  more  exactly  described.     We  begin  with  the  secretionless 


w 

Fig.  144. — Secreting  Epithelial  Cells.  From  a  thin  section  through 
the  mucous  membrane  of  the  human  stomach,  x  560  d.  -p.  Proto- 
plasm ;  s,  secretion ;  a,  two  cells  in  a  resting  state.  The  cell 
situated  between  these  shows  the  beginning  of  the  mucous 
metamorphosis,  e,  The  upper  wall  of  the  cells  on  the  right  has 
burst,  the  contents  have  escaped,  the  granulated  protoplasm 
has  again  increased,  and  the  nucleus  has  again  become  round. 
(Method  No.  12,  Appendix.) 

condition  in  which  the  cylindrical  cell  contains  a  granular  proto- 
plasm, and  an  oval  nucleus  placed  almost  in  the  middle  of  the  cell. 
The  formation  of  the  secretion  now  appears  on  the  free  side  of  the  gland 
«ell,  and  is  shown  by  the  alteration  of  the  granular  protoplasm  into  a 
clear  mass  (Fig.  144,  5,  s).  As  the  process  advances  (c)  larger  masses  of 
protoplasm  are  converted  into  secretion,  and  the  nucleus  and  the  remainder 
of  the  granular  protoplasm  are  pressed  against  the  base  of  cell,  whereby 


298 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


the  nucleus  gradually  becomes  round  or  even  flattened.      The  entire 
cell,  filled  A\ath  secretion,  has  now  become  larger.     Finally,  the  wall  of 

the  cell  ruptures  on  the  free  upper 
surface.  The  secretion  issues  out 
gradually,  while  the  protoplasm  re- 
generates itself  and  the  nucleus  re- 
sumes its  i^revious  oval  form.  The 
cell  thus  passes  back  to  the  state  of 
rest.  Several  of  the  stages  of  the  pro- 
cess of  secretion  are  illustrated  in 
Fig.  145.  The  majority  of  gland  cells 
do  not  perish  in  the  act  of  secre- 
tion, but  they  are  in  a  position 
to  repeat  the  same  process.  The 
cells  of  the  sebaceous  glands  are  ex- 
cepted from  this  rule,  as  secretion  is. 
formed  in  these  by  the  cells  falling  in 
pieces.     (See  also  Secretion.) 

(9)  Gh-owth  of  Cells.— The  growth  of 
cells  is  determined  by  the  activity  of 
the  protoplasm  contained  in  them. 
Seldom  do  they  grow  equally  in  all 
directions,  so  as  to  preserve  the  original  form  of  the  cell.  As 
a  rule,  disproportionate  growth  occurs.  The  original  form  of  the 
cell  is  thereby  changed,  and  it  becomes  distended,  or  flattened,  or  put 
out  of  shape,  etc.  Most  cells  are  soft  and  liable  to  change  their  shape 
under  mechanical  influences.  Thus,  the  cylindrical  epithelial  cells  in 
the  empty  urinary  bladder  assume  flattened  shapes  when  the  bladder  is 
distended. 

(10)  Evolution  of  Cells. — Each  cell  may  be  regarded  as  an  organism 
which  has  a  determinate  period  of  existence.  The  duration  of  life  is 
very  variable.  Some,  such  as  epithelial  cells,  may  pass  through  exist- 
ence in  from  twelve  to  twenty-four  hours  ;  those  of  the  mammary  gland 
may  have  a  more  transitory  existence;  whilst  such  cells  as  those  of 
cartilage  probably  exist  during  the  lifetime  of  the  individual.  Cells 
die  in  various  ways.  They  may  be  mechanically  removed  from  the 
superficial  surfaces,  as  is  the  case  with  epidermic  cells ;  or  they  may 
undergo  chemical  transformations  of  such  a  nature  as  to  be  inconsistent 
with  the  vitality  of  the  cell.  For  instance,  as  frequently  happens  in 
pathological  conditions,  the  cell  may  become  infiltrated  -with  calcareous, 
fatty,  or  amyloid  matter.  Sometimes,  also,  cells  may  break  down,, 
molecule  by  molecule,  undergo  liquefaction,  and  be  absorbed. 


Fig.  145.  —  Section  of  sub-lingual 
gland  of  man,  x  240  d.  Opposite  2, 
six  cells  are  seen  full  of  secre- 
tion, s,  fj ;  two  cells,  containing  no 
secretion,  s,  I,  are  thrust  away  from 
the  centre  of  the  pouch  of  the  gland 
to  form  a  half-moon  or  crescentic 
mass.  This  figure  will  be  repeated 
and  described  fully  in  treating  of 
salivary  secretion. 


STRUCTURE  OF  CELLS  AND  CELLULAR  TISSUES.        299 


Chap.  VIII.— STEUCTURE  OF  THE  VARIETIES  OF  CELLS  AND  OF 
CELLULAR  TISSUES. 

From  the  morphological  point  of  view,  all  the  tissues  are  composed 
of  cellular  elements,  although  in  the  fully  developed  condition  of  certain 
tissues  it  may  be  difficult  to  detect  the  cell  form.  Thus,  while  epithelial 
and  cartilaginous  tissue  and  the  corpuscles  in  the  blood  show  the  usual 
cell  type,  so-called  muscle  and  nerve  fibres  have  become  so  much 
altered  as  to  conceal  the  fact  that  they  also  are  composed  of  cells. 
Modern  physiology,  however,  attaches  so  much  importance  to  the 
doctrine  that  all  tissue  elements  are  formed  of  cells — a  doctrine  also 
having  a  direct  bearing  on  many  pathological  questions — as  to  make  it 
desirable,  in  the  first  instance,  to  take  a  general  survey  of  the  cell- 
elements,  leaving  the  functions  of  these  cell  elements  to  be  afterwards 
.  discussed.^ 

1.  Leucocytes  are  cells  having  no  cell  wall,  and  consisting  of  a 
granulated,  glutinous  protoplasm,  and  of  one  or  more  nuclei.  A  de- 
finite form  cannot  be  ascribed  to  them,  because,  during  life,  they  show 
amoeboid  motion ;  in  a  state  of  rest  they  are  globular  (Fig.  146,  8) ;  their 
size  fluctuates  between  4  and  14  /i.  Leucocytes  are  found  in  the 
lymph  and  chyle  vessels  (lymph  and  chyle  corpuscles),  in  blood-vessels 
(white  or  colourless  blood  corpuscles),  in  the  marrow  of  the  bones 
(marrow  cells),  in  adenoid  tissue,  and  lastly,  scattered  in  the  connective 
tissue  and  between  epithelial  and  gland  cells,  whither  they  have  wan- 
dered by  their  amoeboid  motions.  On  this  account  they  are  sometimes 
called  wandering  cells. 

2.  Coloured  Blood  Cells  (coloured  blood  corpuscles,  Fig.  146) 
are  soft,  ductile,  very  elastic  stirictures,  possessing  a  smooth  surface. 
In  man  and  the  mammalia  they  have  the  shape  of  almost  flat  circular 
discs,  ^  which  are  hollowed  out  on  each  side,  and  consec[uently  resemble 
biconcave  lenses.  The  llama  and  the  camel  are  exceptions  to  this  rule, 
as  their  blood  corpuscles  are  oval.  In  the  case  of  man,  their  surface 
diameter  is,  on  an  average,  7'5  [jl  ;  their  thickness  1"6  /^.  The  coloured 
blood  corpuscles  of  our  domestic  mammalia  are  all  smaller  ;  the  largest 
are  those  of  the  dog  (7 '3  /x).     The  coloured  blood  corpuscles  consist 

^  Histological  details  regarding  the  various  tissues  shortly  described  in  this 
chapter,  which  are  of  special  physiological  interest,  will  be  given  when  we  con- 
sider the  special  functions.  For  example,  the  structure,  etc.,  of  the  blood 
corpuscles  will  be  again  referred  to  in  the  description  of  the  characters  of  blood. 

^  Besides  these,  a  few  spherical  coloured  blood  corpuscles  are  to  be  found  (Fig. 
146,  A  7) ;  they  are  smaller  (5  fi)  than  the  ordinary  red  corpuscles. 


300 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


of  a  stronica  (protoplasm),  which  is  brought  into  close  relation  with  the 
colouring  matter  of  the  blood.    Haemoglobin  gives  to  the  coloured  blood 

corpuscles  their  yellow  or 

A     .  H         If     Ji  greenish-yellow  hue.  Thev 

^  O  ^^   ^   h*  have  no  cell  wall  nor  nu- 

^^S  OO    ^  ■''W    %  "^^^^-^^         cleus.    The  coloured  blood 

^  %JS  // ^j^^'        corj^uscles  of  fishes,   am- 

(;x^'       ^  ^'^       i^^     /^   phibia,  reptiles,  and  birds 

°*^  Q-^,  %      ^1^    ^mj    ^^®     distinguished     from 

^%>'  "'  '^  m  ^^     those    of    mammalia    by 

^  ^  o°o  their  oval  and   biconvex 

T,     ^,r    T,^    A  1      .    r         T,    r  X,    r  shape,  by  their  large  size 

Fig.  146.— Blood  corpuscles — A,  of  man  ;  B,  of  the  frog,  . 

560  times  magnified.     1-6,  disk-shaped  coloured  blood  (in    the    Case    of    the    froo" 

corpuscles.     1,  Deep  focusing ;  2,  high  focusing  of  the  ^ 

objective;  3  and  i,  edgeways;  5,  become  stellated  by  22  11  long,   15  M  broad),   aS 

evaporation ;  6,  after  the  addition  of  water.    7,  Spherical  i 

coloured  blood  corpuscles.  S,  Colourless  blood  corpuscles.  WCll  aS  by  the  ])resence  of 

9,  Small  blood  plates.     10-13,  Coloured  blood  corpuscles 

of  the  frog.  10,  Entirely  fresh,  nucleus  little  distinguish-  a    rOUlld    Or    OVal    UUCleUS. 

able;  11,  some  minutes  later  nucleus  distinctly  visible ;  ^              ■,                                      , 

IS,  seen  on  the  side  ;  13,  after  addition  of  water.     lU,  in      Other     rCSpectS,     they 

Living.     1,7,  Dead  colourless  blood  corpuscles.     (Method  t      i                          ,  •           •      ••> 

No.  13,  Appendix.)  display  properties  similar 

to  those  of  the  mammalia. 

The  size  of  the  coloured  corpuscles  varies  greatly  in  diiferent  animals.  Gulliver 
has  given  the  following  measurements  in  fractions  of  an  inch — 

Diameter. 

^an, ^^ 

Elephant,      -         - ^i^ 

Musk  Deer, u  aVu 

Long  Short 

Diameter.  Diameter. 

Camel, -          ^^  ^Vt 

Ostrich, ^^  ^ij^ 

Pigeon, ^i„  ^\^ 

Humming  Bird, ^^  ^.^^^ 

^^og. ttW  t^Vt 

Crocodile,     --.-..         ^^^  ^^ 

Proteus, ^^  ^ 

Pil^e, -        -  ^^  ^^ 

Sliark, ^,1^  ^^1^ 

Earth-worm, ^i^  ^^i^^ 

Leech  (after  addition  of  water),    -         -  -j-^  g-^Yr 

The  size  of  the  coloured  corpuscles  bears  a  relation  to  the  calibre  of  the  ultimate 
capillaiy  vessels,  which  are  just  large  enough  to  admit  of  their  passage  in  single 
file.  Injections,  therefore,  of  the  blood-vessels  are  more  easily  made  in  reptiles 
than  in  any  other  animals. 

The  addition  of  icater  causes  the  coloured  corpuscles  to  lose  their  colour,  to 
swell  out,  and  become  globular.  Syrup,  gum,  solutions  of  albumin,  and  dense 
saline  solutions,  render  them  flaccid,  misshapen,  irregular  in  outline,  contracted, 
puckered,  etc.     Acetic  acid  appears  at  first  wholly  to  dissolve  mammalian  cor- 


STRUCTURE  OF  CELLS  AND  CELLULAR  TISSUES.        301 

puscles,  but  their  form  may  be  faintly  recognised  on  adding  to  them  tincture  of 
iodine.  But  on  the  oval  corpuscles  of  birds,  reptiles,  and  fishes,  the  effect  is 
simply  to  dissolve,  or  render  very  transparent  the  protoplasm,  while  the  nucleus 
is  unaffected,  and  even  becomes  more  distinct.  Astringent  solutions,  and  especially 
a  solution  of  nitrate  of  silver,  cause  puckerings  and  folds  to  appear  in  the  cell. 
This  is  well  seen  in  the  corpuscles  of  the  newt,  where  also  a  solution  of  boracic 
acid  develops  the  nucleiTS  in  the  form  of  an  oval  body,  from  which  processes 
radiate  outwards.  A  solution  of  magenta  causes  a  minute  molecule  to  appear  on 
the  external  margin,  as  pointed  out  by  Sir  William  Roberts.  The  same  observer, 
also,  was  the  first  to  describe  the  effect  of  a  dilute  solution  of  tannic  acid,  which 
causes  one,  and  sometimes  two,  protrusions  to  take  place  from  the  corpuscle.  A 
stream  of  carbonic  acid  passed  into  frog's  blood  is  quickly  followed  by  the 
appearance  of  the  oval  nucleus,  which  may  again  disappear  under  the  action  of 
air,  or  of  oxygen. 

3.  Epithelial  Cells  are  sharply-defined  cells  consisting  of  proto- 
plasm and  a  nucleus.  A  cell  membrane  is  frequently  awanting,  but 
it  is  often  represented  by  a  more  consolidated  portion  of  the  peri- 
pheral layer  of  protoplasm.  Most  epithelial  cells  are  soft,  and  readily 
adapt  themselves  to  pressure  brought  to  bear  upon  them;  hence 
the  numerous  forms  taken  by  epithelial  cells.  Two  princii^al  forms  may 
be  distinguished — (a)  the  flat,  and  (b)  the  cylindrical  or  jDrismatic. 
There  are  numerous  transitional  forms  from  the  one  kind  to  the  other. 

(a)  Flat  Epithelial  Cells,  flat  cells,  pavement  cells,  seldom  jDossess 
regularity  of  shape.  Pigment  epithelium  alone  (see  Fig.  150)  consists 
of  tolerably  regular  hexagonal  cells ;  in  the  majority  of  cases  the  con- 
tour is  very  irregular. 

(h)  Cylindrical  Epithelial  Cells,  cylinder  cells,  looked  at  from  the 
side,  are  distended  elements,  whose  height  surpasses  their  breadth ; 
looked  at  from  above,  they  appear  polygonal ;  they  are  thus  in  reality 
prismatic.     Epithelial  cells,  which  are  as  long  as  they  are  broad,  are 


Fig.  147. — Epithelial  cells  of  the  rabbit,  isolated,  X  560  diameters.  1, 
pavement  cells  from  the  epithelium  of  the  mucous  membrane  of  the  mouth  ; 
2,  cylindrical  cells,  corneal  epithelium;  3,  cylindrical  cells,  with  cuticular 
edge,  s,  intestinal  epithelium  ;  4,  ciliated  cells — h,  cilia,  bronchial  epithe- 
lium.    (Method  No.  14,  Appendix.) 

termed  cubical  cells.     Many  cylindrical  cells  bear  on  their  upper  surface  a 
striped  border  (Fig.  147,  3),  which  is  a  product  of  the  cell — a  kind  of 


•302 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


cuticular  structure.  Other  cylindrical  cells  have  on  their  free  surface 
delicate  cilia,  which  during  life  show  oscillating  motion  in  a  certain 
direction.     We  call  these  ciliated  or  Jiagellate  cdls.'^ 

Epithelial  cells  are  so  bound  together  that  they  either  touch  each 
other  with  their  smooth  surfoces  {i.e.  through  the 
interposition  of  an  intermediate  or  cement  sub- 
stance present  in  very  small  c[uantity),  or  they  are 
united  by  variously  shaped  prolongations.  There 
are  also  included  under  such  prolongations  the  deli- 
cate bristles  and  filaments  Avhich  are  visible  on  the 
upper  surface  of  certain  epithelial  cells  (Fig.  148). 
These  are  connecting  threads  which  penetrate 
the  cement  substance  between  two  epithelial 
cells,  and  effect  a  connection  Avith 
bouring  epithelial 
bristles  and 
cells ;     the    bristles 


'^iw-^ 


•'■^^jjinll^' 


neigh- 
cells.  Cells  proAdded  with 
filaments  are  termed  bnstle 
themselves     have    been    indi- 


FlG.  14S. — Spinous,  bris-    gricli 
tie,    or    furrowed    cells.     '"^^^ 
a,  from   the   undermost 
layers  of  the  human  epi- 
dermis; 6  a  cell  from  a   catcd  of  late  by  the  appropriate  term,  intercellular 

papillary  tumour  of  the  ''  l  r      r  j 

human  tongue. 


bridges  (Fig.  149). 


^ 


^V 


Fig.  14f). — From  a  perpendi- 
cularsection  through  the  stra- 
tified pavement  epithelium  of 
the  stratum  mucosiim  of  the 
epidermis,  x  560  d.  Seven 
pavement  epithelium  cells 
bound  to  each  other  by  inter- 
cellular bridges.  (Method  No. 
15,  Appendix.) 


Fig.  150.— Simplepave- 
ment  epithelium  (pig- 
ment epithelitim  of  the 
retina)  of  man,  x  560 
d.  (Method  No.  16, 
Appendix.) 


Fig.  151. — Simple  cylindrical  epi- 
thelium (intestinal  epithelium) 
of  man,  x  560  d.  c,  Stripe-shaped 
cuticular  edge,  cylindrical  cell ; 
tp,  tunica  propria,  from  small 
intestine.  (Method  No.  17, 
Appendix.) 


Varieties  of  Epithelial  Layers. 

Epithelial  cells  are  arranged  sometimes  in  simple,  sometimes  in  com- 
pound, layers.     We  accordingly  distinguish — 

(1)  Simple  Pavement  Epithelium. — This  variety  is  observed  in  the  pigment 
epithelium  of  the  retina  (Fig.  150),  epithelium  of  the  alveoli  of  the  lungs, 
of  the  coat  of  the  stomach,  of  the  rete  vasculosmn  Hcdleri  of  the  skin  and 
of  the  lining  membrane  of  the  labyrinth.  The  epithelium  formed  of  one 
layer  of  cubical  cells  constituting  the  covering  of  the  plexus  choroidea, 
and  the  epithelium   on  the  inner  surface  of  the  capsule  of  the  lens,  in 

^  The  specially  differentiated  sense  epithelium  cells  will  be  described  in  treating 
of  the  senses. 


STRUCTURE  OF  CELLS  AND  CELLULAR  TISSUES.        303 

the  thyroid  gland,  and  in  most  other  glands,  also  belong  to  this  class  of 
epithelium. 

(2)  Simple  Cylindrical  Epithelium,  Fig.  151,  such  as  the  epithelium  of 
the  intestinal  canal  and  of  many  ducts  of  glands. 

(3)  Simple  Ciliated  Ep)ithelium  exists  in  the  most  delicate  bronchise,  in 
the  uterus,  in  the  Fallopian  tubes,  in  the  nostrils,  and  in  the  central 
canal  of  the  spinal  cord. 

(4)  Stratified  Pavement  Epithelium,. — In  this  variety,  the  cells  are  not  all 
pavement   cells,    as   the   deepest   layer   consists   of 
cylindrical   cells.     Above   this,   there    are    several 

layers  of  differently    shaped    bristle  cells   (mostly  ^     ^  J    ^^^ "^--^ 

in  the  form  of  irregular  polygons.  Fig.  152),  and  on       _^_^^^^-J^r:'^'.- 
these  are  placed  cells  more  and  more  flattened  toAvards         -  '- 

the  surface  of  the  epithelial  layer.     Stratified  pave-        -  -        :; 

ment   epithelium   is   found   in   the   mouth,  in  the 

cavity  of  the  throat,  in  the  oesophagus,  on  the  vocal 

cords,  on  the  conjunctiva,  in  the  vagina,  and  in  the 

female  urethra.     The  epidermis  is  also  covered  over    ' 

with  stratified  pavement  epithelium ;  but  the  latter 

is  characterized  by  the  cells  of  the  layer  nearest  to  ^-l.       "\ 

the  surface  being  changed  to  small  horny  scales,  'w 

while  they  have  lost  their  nucleus.     On  the  nails  no.  i52.-stratifiedpave- 

and  hair  also,  horny,  but  in  this   case  nucleated,  S'manf x^fo"  d  ^""l^y. 

scales  are  found.  _  s^J^fl^af^./eilk'^iMei^od^ 

(5)  Stratified  Cylindrical  Epithelium  is,  in  the  case  of  ^°-  ^^'  Appendix.) 
man,  found  only  on  the  conjunctiva  palpeh'arum.     The  arrangement  of  the 
layers  is  the  same  as  in  the  next  form. 

(6)  Stratified  Ciliated  Epithelium. — The  cells  next  to  the  surface  are 
cylindrical  and  they  bear  minute  hair-like  processes,  cilia;  in  the 
deepest  layers,  roundish  cell  elements  are  met  with,  and  in  the  middle 
layers,  spindle-shaped  ones  occur.  Stratified  ciliated  epitheliimi  is  found 
in  the  larynx,  in  the  trachea,  and  in  the  large  bronchiee,  in  the  nostrils, 
and  in  the  upper  part  of  the  throat,  in  the  Eustachian  tube,  and  in 
the  testicles  1  (Fig.  153). 

4.  Connective  Tissue  Cells  are  recognized  as  such  only  when 
found  in  the  tissues,  that  is  to  say,  an  isolated  connective  tissue 
cell  is  indistinguishable  from  a  leucocyte.  In  form  they  are 
very  variable.  Connective  tissue  cells  are  either  flat,  polygonal, 
bent,  or  twisted  in  various  directions;  or  they  are  roundish,  oval, 
spindle   or   star-shaped.      (See    Connective   Tissue.)      Their    arrange- 

1  The  embryonal  origin  of  epithelial  layers  has  already  been  indicated,  p.  251. 


304 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


ment  is  the  reverse  of  that  of  epithelial  cells,  inasmuch  as  the  'rule 
is  that  they  are  separated  from  their  neighbours  by  means  of  consider- 


'J:.v.-4 


Fig.  153.  —  Stratified 
ciliated  epitlielium: 
1,  oval ;  2,  spiudle 
shaped  ;  3,  cylindrical 
cells.  X  500  d.  From 
the  mucous  mem- 
brane of  the  nose  {ra- 
gio  respiratoria)  of 
man.  (Method  No. 
19,  Appendix.) 


Fig.  154. — Endothelial  cells  on  the  serous 
covering  of  the  diaphragm.  (Some  of  the 
ragged  openings  are  probably  accidental.) 


able  masses  of  connective  tissue.  Endothelial  cells  are  an  excep- 
tion to  this  as  they  have  a  great  resemblance  to  simple  flat  ej^ithelium 
and  can  be  distinguished  only  by  their  anatomical  position  (in 
the  cavities  of  the  joints,  in  the  sheaths  of  tendons,  in  the  bursce  mucosce, 
and  on  the  inner  surface  of  the  heart,  blood-vessels,  and  lymphatics). 

(Fig.  154.)  The  protoplasmic  nucleated 
body  of  the  cells  of  connective  tissue 
may  contain  granules  of  colouring  matter. 
The  cells  are  thereby  changed  into  pig- 
ment cells,  vrhich  occur  in  man  only  in 
the  eye,  but  in  many  of  the  lower  ani- 
mals they  are  widely  diflPused.  Other 
mrttefi"n~theii'pTOtopksml'*^a?A^^^^^^  Connective  tissue  cells  may  contain  small 
Td^d  i^H^ranofLf  oTSr^am^;  clrops  of  fat,  which,  Avheu  they  become 
:^:^^t^^^^^^^^C^^  la^ge.  give  a  spherical  shape  to  the 
^^^^^l^lT^tS^   cell.     Such  are  termed  fatty  cells.     (See 

e,  another  with  granules  of  melanin.  pjg_  1 5  5^  f/. )     Jn  fatty  CcUs,  the  protoplasm 

forms  only  a  narroAV  border,  situated  on  the  periphery  of  the  cell.  The 
flattened  nucleus  is  found  at  the  side  of  the  cell.  The  border  is  fre- 
quently so  thin  that  it  sinks  out  of  sight.     (See  Fig.  155.) 

5.  Fat  or  Adipose  Tissue  Cells  are  nearly  akin  to  the  fatty  cells 
above  described,  but  they  are  nevertheless  distinguished  from  the  latter 
by  the  fact  that  they  are  united  without  the  interposition  of  an 
intermediate  substance,  so  as  to  form  in  certain  parts  of  the  body  a 
tissue  interpenetrated  by  numerous  blood  vessels,  lymph  vessels,  and 


STRUCTURE  OF  CELLS  AND  CELLULAR  TISSUES.       805 

nerves,  namely,  fatty  or  adipose    tissue,  whicli  plays  a  very  important 
part   in    various    physiological    processes.      In    extreme    emaciation. 


Fig.  156. — Fat  tissue  cells  from  the  axilla,  x  240d.  y4,of  an  individual  only  a  little 
emaciated  ;  1,  on  focusing  the  objective  on  the  equator  of  the  cell ;  2,  objective 
slightly  raised  ;  3,  U,  cells  put  out  of  shape  by  pressure  ;  p,  traces  of  protoplasm 
situated  in  the  neighbourhood  of  the  nucleus.  B,  of  a  highly  emaciated  indivi- 
dual ;  k,  nucleus  ;  /,  small  drops  of  fat ;  t",  blood  capillaries  ;  b,  bundle  of  connec- 
tive tissue.     (Method  No.  20,  Appendix.) 


we  find,  in  individual  fat  tissue  cells,  the  fat  shrunk  to  small  drops,  and 
its  place  occupied  by  a  pale  protoplasm,  mingled  with  mucous  fluid. 
The  cell  is  no  longer  spherical,  but  has  become  flat.  Such  cells  are 
termed  serous  fat  cells. 

6.  Muscle  Cells. — The  fibres  of  the  muscles  appear  in  two  forms, 
which  we  term  the  smooth  and  the  transversely  striated.  Both  are 
cells,  of  which  the  body  is  greatly  extended  in  a  longitudinal  direc- 
tion. 

(1)  The  smooth  muscular  fibres  (Fig.  157)  (contractile  fibre  cells),  are 
spindle-shaped,  cylindrical,  or  slightly  flattened  cells,  having  pointed 
ends.  Their  length  fluctuates  between  45  and  225  /x ;  their  breadth 
between  4  and  7/x  ;  in  the  pregnant  uterus,  still  longer,  smooth  muscu- 
lar fibres,  measuring  ^  mm.,  have  been  found.  They  consist  of  a 
homogeneous  protoplasm,  containing  a  rod-shaped  nucleus.  ^  This  nucleus 
is  characteristic  of  smooth  muscular  fibres.  The  fibres  are  imited 
firmly  to  each  other.  Smooth  fibres  are  found  in  the  intestinal  canal, 
in  the  smaller  bronchial  tubes,  in  the  gall  bladder,  in  the  pelvis,  in  the 
kidney,  in  the  ureter,  in  the  urinary  bladder,  in  the  sexual  organs,  in 
blood  and  lymph  vessels,  in  the  eye,  and  in  the  skin.  As  this  kind  of 
fibre  is  not  subject  to  voluntary  control,  it  is  often  called  involuntary 
muscular  fibre. 

(2)  The  transversely  striated  muscular  fibres  are  to  be  recognized  as 

^  In  individual  smooth  muscular  fibres  a  longitudinal  striation  of  the  protoplasm 
has  been  observed. 

I.  U 


806 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


cells  only  by  studying  their  development.  As  the  result  of  a  colossal 
growth  in  length,  of  continued  division  of  the  nucleus,  as  well  as  of 
peculiar   difterentiation    of  their   protoplasm,   they   have   attained   to 


Fig.  1.07. — Two  smooth  muscular  fibres  from  the  small  intestine  of  a  frog. 
Isolated  by  means  of  35  per  cent,  solution  of  caustic  potash.  The  nuclei 
have,  by  action  of  the  caustic  potash,  lost  their  characteristic  form. 
(Method  Xo.  21,  Appendix.) 

highly  complicated  forms.  They  have  the  shape  of  long  cylindrical 
fibres,  which  are  usually  rounded  off  at  the  ends,  or  obtusely  pointed, 
but  in  certain  cases  (muscles  of  the  eye  and  muscles  of  the  tongue)  the 
fibres  are  branched  (Fig.  158).  Their  length,  only  in  rare  cases, 
exceeds  4  cm.  ;  their  thickness  fluctuates  between  15  and  50 /x  ; 
and  the  muscles  of  the  face  have  finer  fibres  than  the  muscles  of  the 
trunk. 

The  following  table  gives  certain  measurements  of  muscular  fibres  in 
fractions  of  an  inch.     (Allen  Thomson.) 


Muscle  of 

Diameter  of  Fibres. 

Distance  ok 

Transverse 

Stri^. 

Greatest. 

Least. 

Average. 

Birds,     - 

^"5(r 

TTi7TF 

1 

TTTT-OD 

Mammalia, 

TTTJ 

TT"iJ"S" 

-e\-(i 

TO 0  0  0 

Man, 

TTS" 

1 
<>16 

T-ou 

TF^uU 

Reptiles, 

TXTU 

1*00 

-^ 

TTioT) 

Fishes,    - 

1 

"B5 

7T^ 

1 

TTTTnr 

Insects,  - 

1 

1 

^h> 

ITsW 

Each  transversely  striated  fibre  consists  of  the  foUoAving  parts — 
(1)  A  structiu-eless  covering  or  membrane,  termed  the  sarcolemma,  which 
surrounds  the  fibre  like  a  sac.  (2)  Oval  nuclei,  placed  parallel  to  the 
axis  of  length  of  the  muscular  fibres,  Avhich  nuclei  lie,  in  the  case  of  the 
mammalia,  between  the  sarcolemma  and  muscle  substance  ;  but  in  other 
vertebrates,  in  the  muscle  substance  itself,  in  Avhich  they  are  surrounded 
by  a  very  small  amount  of  protoplasm.  This  protoplasm  is  the  remain- 
der of  the  original  cell  protoplasm  not  spent  in  the  up-building  of  the 
transversely  striated  muscle  substance,  and  it  is  accumulated  especially 
at  the  poles  of  the  nuclei.  The  granulated  accumulations  of  protoplasm 
are  termed  interstitial  granules.     (3)  The  muscle  substance.     It  is  trans- 


STRUCTURE  OF  CELLS  AND  CELLULAR  TISSUES.       307 

versely  striated,  i.e.  it  shows  alternately  dark  and  narrower,  and  clear 
and  broader  transverse  bands.  The  substance  of  the  dark  transverse 
bands  is  doubly  refractive  (cmisotrojpk  substance) ;  that  of  the  bright 
transverse  bands  is  singly  refractive  {isotropic  substance).  Under  strong- 
magnifying  powers,  double  transverse  stripes  {transverse  lines)  may  be 
perceived  (Fig.  164),  which  divide  the  clear  transverse  bands  into  two 
■equal  parts ;  in  the  case  also  of  the  dark  transverse  bands,  another  set 
of  transverse  stripes,  the  so-called  middle  discs,  has  been  described. 
The  collective  stripes  and  bands  (with  the  exception  of  the  middle  discs) 
penetrate  the  entire  thickness  of  the  muscular  fibres,  and  they  are  thus 
in  reality  discs.  Besides  the  transverse  striation,  there  is  also  to  be 
observed  a  more  or  less  pronounced  longitudinal  striation  of  the  muscular 
fibres.  Certain  reagents,  for  example,  solution  of  chromic  acid,  cause 
this  longitudinal  striation  to  manifest  itself  still  more  distinctly,  and 
•effect  even  a  falling  asunder  of  the  muscular  fibre  lengthwise  into 
delicate  similarly  stri2)ed  threads,  which  are  termed  fibrils.  Other 
reagents,  for  example,  solutions  of  hydrochloric  acid,  bring  the  transverse 
striation  more  distinctly  into  prominence,  and  they  can,  moreover,  cause 
£i  falling  asunder  of  the  muscular  fibres  transversely  into  discs.  Fibrils 
iind  discs  can  fall  asunder  into  still  smaller,  roundish-edged,  anisotropic 
portions,  which  are  termed  the  primitive  muscle  particles  or  the  sarcous 
elements. 


Fig.  158. — Portions  of  isolated  transversely  striped  muscular  fibre  of  a  frog, 
X  50  d.'  1.  Effects  of  water;  s,  s',  sarcolemma.  At  x  the  muscular  sub- 
stance has  been  torn  asunder,  its  transverse  striation  is  not  visible,  but 
its  longitudinal  striation,  on  the  contrary,  is  distinctly  seen.  2.  Action 
of  acetic  acid;  k,  nuclei.  The  delicate  puncturing  corresponds  to  the  inter- 
stitial granules.  3.  Action  of  a  concentrated  solution  of  caustic  potash  ; 
ends  rounded  off,  the  numerous  nuclei  appear  to  have  flowed  into  a  vesicle 
or  swelling  e ;  the  transverse  striation  of  the  substance  of  the  muscle.'?  is  in 
2  and  3  invisible  under  this  magnifying  power  (Method  No.  22,  Appendix). 
4.  Branched  muscle  fibre  from  the  tongue  of  a  frog  (Method  No.  23, 
Appendix) 


308 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


Fig.  15fi. — Polarizer  for  microscope. 
A,  Nicol's  prism  ;  B,  brass  case  ;  D, 
end  next  mirror  ;  C,  plano-convex  lens 
— which  is  not  necessary. 


Examination  of  muscn/nr  Jibre  by  polarized 
liijhi  (see  p.  66). — As  already  described, 
when  examined  by  ordinary  light,  a  muscular 
fibre  is  seen  to  consist  (1)  of  a  substance 
which  forms  the  sarcous  elements,  highly 
refracting,  and  black  M^hen  seen  by  trans- 
mitted light  ;  and  (2)  of  an  intermediate  or 
fundamental  substance,  ■which  is  much  less 
refractive,  and  is  clear  by  transmitted  light. 
Suppose  now  that  arrangements  are  made  by 
which  the  fibre,  whilst  on  the  stage  of  the 
microscope,  can  be  placed  between  crossed 
Nicol's  prisms.  This  is  accomplished  by 
placing;  one]^  Nicol's  prism  below  the  stage 
{the  {j}o/arize7;  Fig.  159),  and  another  in  the 
eyepiece  of  the  microscope  (the  analyzery 
Fig.  160).  Either  or  both  of  these  pripms 
are  capable  of  rotation,  and  they  may  be  so 
rotated  with  reference  to  each  other  that 
when  we  look  through  the  microscope  the 
field  is  quite  dark.  It  will  then  be  found 
that  if  a  striated  muscular  fibre  is  in  the 
dark  field,  the  sarcous  elements  (represented 
by  the  dai'k  transverse  bands  seen  with  ordi- 
nary light)  shine  very  distinctly,  while  the 
clear  band  seen  with  ordinaiy  light  is  now 
invisible.  The  observation  is  more  striking 
if  the  slide  containing  the  muscular  fibre  is 
placed  on  a  thin  plate  of  selenite.  As  only 
doubly  refractive  substances  thus  shine  out 
in  the  dark  field  of  crossed  Nicol's,  it  follows 
that  the  sarcous  elements  are  anisotropic  or 
doubly  refractive,  while  the  substance  which 
unites  the  contiguous  discs  is  isotropic,  that 
is,  singly  refractive.  According  to  Engel- 
mann,  contractility  is  manifested  exclusively 
by  the  anisotropic  portion.  Each  sarcous 
element  behaves  as  a  doubly  refractive  body 
having  only  one  positive  axis,^  of  which  the 
optical  axis  is  parallel  to  the  long  axis  of  the  muscle.  As  they  change  their  form 
during  contraction,  becoming  shorter  and  thicker,  they  cannot  be  regarded  simply 


Fig.  160. — Analjv.er  for  microscope. 
A,  Nicol's  prism  ;  B,  eyepiece ;  C,  field 
yrlass  ;  D,  eyeglass.  Other  references 
of  no  importance. 


1  A  body  having  its  molecules  uniformly  arranged  in  all  directions  afi'ects  light 
only  by  simple  refraction,  that  is,  the  incident  ray  gives  rise  to  one  refracted  ray, 
and  the  crystal  possesses  one  refractive  index.  When,  on  the  other  hand,  the 
molecular  structure  of  a  body  possesses  parts  of  different  density  in  certain  direc- 
tions, it  manifests  double  refraction,  that  is,  a  ray  of  light  traversing  it  is  divided 
into  two  rays,  one  of  which  is  bent  more  out  of  its  course  than  the  other.  Common 
glass  is  simply  refractive,  and  is  said  to  be  isotropic ;  but  if  it  be  compressed  in 
one  direction,  it  may  become  doubly  refractive  or  anisotropic. 


_i_i::li_ 

?;^j~'jv~Ti' 

1      1      1 

-y}-_\  ...   1^— - 

Ij 

— I— |— |— 

)  , 

my--^ 

r'' 

h 

STRUCTURE  OF  CELLS  AND  CELLULAR  TISSUES.       809 

as  double  refractive  bodies  like  crystals,  but,  as  suggested  by  Briicke,  they  must 
consist  of  a  great  number  of  small  doubly  refractive  particles,  to  which  he  has 
given  the  name  of  disdiaclasts,  and  which  he  supposes  are  irregularly  distributed 
through  the  fundamental  substance  (Fig.  168).  The  latter,  which  may  be  termed 
inicsde-plasma,  is  a  viscous  liquid  capable  of  absorbing  water  freely,  while  the 
disdiaclasts  are  more  dense  and  are  less  capable  of  taking  up  water.  As  has 
been  remarked  by  Schafer,  Briicke  himself  pointed  out  that  in  living  muscle  at 
rest  the  whole  of  the  muscular  substance  appears  doubly  refracting,  and  that  it 
is  only  in  contraction  that  the  alternate  stripes  appear  singly  refracting.^ 

Some  authors  have  claimed  the  fibrils,  others  the  discs,  and  others 
again  the  sarcous  elements,  as  the  primary  form  elements  of  the  fibres  of 
the  muscles.  In  the  latter  case,  we  would  have  to 
represent  the  building  up  in  such  a  manner  that  the 
fibrils  are  formed  from  sarcous  elements  placed  so  as 
to  form  a  row  and  the  discs  from  the  sarcous  elements 
being  placed  side  by  side,  in  both  cases  assuming  that 
the  sarcous  elements  cohere. 

Various  theoretical  views  have  been  advanced  re- 
garding the  ultimate  structure  of  striated  muscular 
fibre,  and  the  question  must  still  be  regarded  as 
unsettled.'^      A  view,  regarded  with   favour  for  some  ^ 

'        =  _  Fig.  161.— Showing 

time,  was  that  the  muscular  fibre  might  be  regarded  hypothetical  views 

-  "^  °  regarding  the  struc- 

as  built  up  of  small  caskets  (see  Fig.  161),  bounded  ture    of    striated 

■^  _  ^  .  muscle.   Four  fibres 

at  the  two  ends  by  a  thin  membrane  or   band  in  the  side  by  side.     «, 

ni7-ir-)7-  T7-  clear  bands  or  discs, 

centre  of  the  clear  band,  called  Dome  s  line  or  Krause  s  each  formed  of  two 

clear  bands  or  discs, 

membrane,  c,  and  laterally  by  the  sarcolemma.     in  this  termed  the  lateral 

,.  11/P11  discs  of  Encjdmann, 

casket  there  were  supposed  to   be  (irom  above  down-  separated  by  a  thin 

wards  in  Fig.  161)— (1)  a  thin  clear  disc,  the  lateral  disc  known   as  dou/s 

of  E^igelmann;  (2)  a  disc  of  dark  substance,  the  sarcous  membrane:  6,' two 

element  of  Boivrnan ;  (3)  in  the  centre  of  this  disc,  an  ill-  stance°constitutiDg 

J    n        -I  1  1,  j.-j.j.-j.T_  7'  7-        the  sarcouis  elements 

defined  granular  substance  constituting  the  median  disc  of  Bomaan,  having 
of  Hensen,  h ;  and  (4)  another  lateral  disc  of  Engelmann.  lu-defined^band  or 
Further,  the  dark  portions  forming  the  sarcous  elements  J^",®' of^HenTenTc, 
of  Bowman  are  the  anisotropic  or  doubly  refractive  part,  ^opic  Vr'singVre- 
while  the  clear  portion,  formed  of  two  discs  of  Engel-  f  ^'^an^fsotropic^"  or 
mann  separated  by  Dobie's  line,  is  singly  refractive  or  ^"^^J^  refractive 
isotropic.  These  appearances  have  undoubtedly  been 
figured  and  described,  but  they  are  to  be  regarded  as  optical  expres- 

^  Briicke,  Physiologie,  p.  465. 

^  An  excellent  account  of  this  subject  is  given  by  A.  van  Gehuchten,  in  Etude 
.sur  la  Struchire  Intime  de  la  Cellule  Muscidaire  Striee. — La  Cellide,  tome  ii. 
'1^  Fascicule. 


310 


THE  PHYSIO  LOO  Y  OF  THE  TISSUES. 


sions  of  layers  of  substances  acting  differently  on  light,  and  also  some- 
times superposed,  so  that  the  structure  of  one  fibre  shines  through,  and 
affects  the  appearance  of,  the  one  above  it.  There  is  also  the  further 
difficulty  that  if  a  living  nnxscular  fibre  is  examined  under  the  micro- 
scope, especially  A\ath  high  powers,  the  amount  or  degree  of  relaxa- 
tion or  of  contraction  affects  in  a  marked  Ava)^  the  optical  appearances, 
so  that  the  fibre  may  present  a  different  appearance  M'hile  at  rest  from 


Fig.  1C2. — Living  muscular 
fibre  from  Geotrupes  ster- 
coranus. 


Fig.  163.— The  same  fibre 
seen  by  polarized  light,  with 
crossed  Nicol's  prisms. 


Avhat  it  shows  in  a  condition  of  contraction.  Thus,  a  fibre  may  show  the 
appearance  represented  in  Fig.  162,  in  which  the  clear  bands  are  narrow, 
Dobie's  line  dark  and  well  defined,  and  the  dark  band  very  wide  :  or  a 
fibre  may,  in  another  condition,  show  more  details  of  structure,  as  in 
Fig.  164.  In  Fig.  163  the  same  fibre  as  is  represented  in  Fig.  162  is  seen 
as  it  appears  in  the  dark  field  of  crossed  Nicol's  prisms,  with  polarized 
light.  It  will  be  observed  that  the  dark  anisotropic  portion  of  Fig.  162 
is  clear  and  brilliant  in  Fig.  163,  while  Dobie's  line,  and  the  part  on 
each  side  of  it,  is  dark.  I  have  recently  convinced  myself,  after  a  study 
of  muscular  fibre  with  the  use  of  chloride  of 
gold,  that  the  appearances  shown  in  Figs. 
162,  164,  165,  and  167,  can  be  seen,  and 
they  support  the  view  that  the  muscle  sub- 
stance is  composed  of  rod-like  structures,  as 
first  described  by  Professor  E.  A.  Schafer.^ 
Whether  these  rods,  in  turn,  are  only  the  optical  expressions  of  a 
fibrillar  net-work  Avith  elongated  meshes,  as  advanced  by  Marshall,  is 
in  my  opinion  more  doubtful.  I  have  not  been  able  to  satisfy  myself 
upon  this  point,  and  especially  have  I  failed  in  detecting  appearances 
favoiu-ing  the  vieAv  that  there  is  a  net-Avork  Avith  irregularly  formed 

^  As   to   Schiifer's   views,    see   Philosophical    Transactions,    1873,    and   Quain's 
Anatomy,  vol.  ii.  p.  123,  et  seq. 


Fig.  164.- •'Muscular  fibre 
from  Hydi-ophilus  pisccus 
(large  water-beetle),  show- 
ing all  the  details  of  struc- 
ture represented  in  the 
diagram.  Fig.  161. 


STRUCTURE  OF  CELLS  AND  CELLULAR  TISSUES.        311 

meshes  in  the  clear  disc.  The  conception  of  a  muscular  fibre  as  an 
elongated  cell  in  which  the  fibrillar  net-work  assumes  a  regular  arrange- 
ment is  one  of  much  significance,  as  it  brings  muscular  fibres  into  the 
general  category  of  cells. 


Fig.  165.— Muscular 
fibre  of  Geotnipes 
stercorarius,  living, 
showing  rod-like 
structures  passing 
longitudinally  in 
the  dark  substance, 
and  rod  or  some- 
what square-shaped 
points  or  dots  in  the 
clear  substance. 


Fig.  160. — Same 
fibre  as  in  Fig. 
165,  seen  with 
polarized  light. 
Dark  bands  of 
Fig.  165  are  the 
clear  bands  of 
this  Figure. 


Fig.  167. — Muscular 
filire  from  Geophilus, 
showing  rod  -  like 
structures  running 
longitudinally  with 
dots  or  points  at 
their  ends. 


Fig.  16S.— Same  fibre 
as  in  Fig.  167,  seen 
with  polarized  light. 
Observe  that  the  rods 
and  the  dots  of  Fig.  167 
are  clear,  and  are 
therefore  doubly  re- 
fractive or  anisotropic. 


Striated  muscle  fibres  are  found  in  the  muscles  of  the  larynx,  of  the 
extremities,  of  the  eye,  and  of  the  ear.  They  are  also  found  in  the 
tongue,  in  the  pharynx,  in  the 
upper  half  of  the  oesophagus, 
in  the  larynx,  and  in  the 
muscles  of  the  genital  organs 
and  of  the  rectum.  In  the 
case  of  many  animals,  e.g.  the 
rabbit,  two  different  sorts  of 
transversely  striped  muscles 
are  found ;  red  (for  example, 
the  semitendinosus  and  the 
soleus),  and  white  (for  ex- 
ample, the  adductor  magnus). 
The  red  muscles  contract 
slowly,  the  white  ones  quickly, 
and  they  also  showmicroscopic 
differences,  inasmuch  as  the  fibres  of  the  red  muscles  possess  a  some- 
what irregular  transverse  striping,  a  more  distinct  longitudinal  striping, 
and  a  larger  number  of  roundish  nuclei  than  the  pale  variety.  In  some 
animals,  the  two  kinds  of  muscular  fibre  appear  to  be  separated  from 


Fig.  169. — B.  Portion  of  a  human  muscuhir  fibre, 
X  560  d.  (a)  Anisotropic  and  (i)  isotropic 
transverse  bands  ;  (5)  transverse  line  ;  (k)  nuclei. 
(Method  No.  23  a,  Appendi.x;.)  A.  The  end  of  the  mus- 
cular fibre  of  a  frog,  x  240  d.  Splitting  into  fibrils 
(/)  )  W  nucleus.     (Method  No.  24,  Appendix). 


:312 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


lar  fibres,  a,  low  degree 
I),  a  higher  ;  and,  c,  the 
highest  degree. 


one  another  in  particular  muscles ;  hut  in  others,  as  in  man,  the  two 
kinds  of  fibres  are  sometimes  mixed  in  the  same  muscle.  The  con- 
traction of  the  transverse  striped  muscles  is  quick  and  under  the  control 
of  the  Avill,  and  hence  this  kind  of  muscle  is  often  termed  voluntary 
muscle.  When  the  fibre  contracts,  the  contraction 
occurs  in  the  broad,  dark,  transverse  band,  which, 
when  contracted,  increases  in  breadth,  while  the 
clear  discs  and  the  narrow,  dark,  transverse  band  play 
a  purely  mechanical  part. 

Muscular  fibre  is  sometimes  the  seat  of  fatt}' 
changes,  in  which  the  striae  disappear,  and  the  muscle- 
substance  becomes  crowded  with  small  molecules  of 
fat  (Fig.  170). 

The  smallest  blood-vessels,  or  capillaries  of  muscle, 
form  a  fine  network  of  elongated  meshes  between  the 
fibres,  but  not  extending  within  the  sarcolemma,  as 

Fio.  170.— Fatty  degen-  <5}ir,TVTi  in  Fi'a    T71 
ci-ation  of  human  musou-  SnOWn  lU  J^lg.    i/i. 

(3)  The  muscular  fibres  of  the  heart  occupy  a  special 
position.  They  show  transverse  striation,  but  it  is 
not  so  distinct  as  in  ordinary  striated  muscular  fibre. 
A  consideration  of  their  development  as  well  as  their 
behaviour  under  the  microscope  show  that  the  mus- 
cular fibres  of  the  heart  are  only  modified  contractile 
fibre  cells.  In  animals  low  in  the  scale  {e.g.  the  frog) 
they  are  spindle-shaped,  provided  with  a  large 
nucleus,  the  protoplasm  is  distinctly  striped  trans- 
versely as  well  as  longitudinally  (Fig.  112,  A);  in  the 
mammalia  the  fibres  take  the  form  of  short  cylinders, 
whose  ends  are  often  irregularly  dentate  (Fig.  172,  B). 
The  protoplasm  is  differentiated  into  transverse 
striped  fibrils,  between  which  the  remains  of  non- 
differentiated  protoplasm  may  still  be  seen.  Longi- 
tudinal striation  is  often  very  distinct.  Around  the 
simple  or  duplicated  nucleus,  there  lie  masses  of 
homogeneous  protojDlasm,  and  granules  exist  in  veiy 
large  quantities.  The  sarcolemma  is  absent.  The 
connection  of  the  irregularl}^  cubical-shaped  fibres 
by  means  of  short,  crooked,  or  transverse  processes  is 
characteristic  of  the  muscular  fibres  of  the  hearts  of 
Fio.  171.— Capillary  net-  the  higher  aiiimals  (Fig.  172,  B). 

work  of  striated  muscu-        -.^  ii-i  77         7  i  t-t.t 

larfibre.  a,  arteriole ;  6,      Muscular  fibres  are  developed,  as  already  indicated, 

venule:  c  and  d,  capil-  p  ,i  i  ,•  <?       n  -i   ,^  ii-    t      j-  r 

lary  network  from  the  elongation  of  ceils  and  the  multiplication  oi 


STRUCTURE  OF  CELLS  AND  CELLULAR  TISSUES.        313 


embryonic  cells  in  the  mesoderm.     Striation 


u 

i  II 

|i 

1  ft 


Fig.  172. — A  and  B,  fibres  of  the  muscles  of  the  heart  isolated 
in  potash.  ^ ,  of  a  fro^  ;  B,  oi  a.  rabbit,  x  Crooked  processes 
(Method  No.  25,  Appendix).  C,  from  a  longitudinal  section 
through  a  papillary  muscle  of  man.  Fat  granule  on  the  poles  of 
the  nucleus.  (Method  No.  26,  Appendix.)    All  the  fibres  x  240  d. 


nuclei.  These  cells  are 
appears  first  at  one  side 
and  it  gradually  passes 
around  the  fibre  and  on- 
wards to  its  centre.  The 
nuclei  are  at  first  near 
the  centre  of  the  fibre, 
but  they  are  pushed  by 
degrees  to  the  circumfer- 
ence until  they  rest  below 
the  sarcolemma,  which 
is  formed  at  a  compara- 
tively late  stage  in  the 
development  of  the  fibre.  ^ 
7.  The  Nerve  Cells 
(Ganglion  cells)  are  ir- 
regularly-shaped cells  of 

very  variable  size  (10  to  100  /x).  There  are  spherical  and  spindle- 
shaped  ganglion  cells.  Star-shaped  cells  are  also  very  frequent,  that  is, 
the  protoplasm  sends  out  pro- 
longations of  irregular  size  and 
length.  The  majority  of  these 
subdivide  continuously,  and 
end  in  a  complicated  network 
of  delicate  fibrils.  Such  pro- 
cesses of  nerve  cells  are  called 
poles  (Fig.  174,^).  The  pole, 
however,  may  run  for  a  long 
distance,  and  is  associated 
with  a  medullary  sheath,  by 
means  of  which  it  comes  to  be 
a  meclullatecl  nerve  fibre.  The 
pole  consequently  corresponds 
to  a  part  of  the  nerve  fibre 
called  the  axis  cylinder,  and  it  is  on  that  account  termed  an  axis  cylinder 
pole  (Fig.  174,  ax).  Ganglion  cells  with  two  poles  are  termed  hipolar, 
cells  with  several  poles  are  termed  multipolar ;  one  may  also  speak  of 
unipolar  and  apolar  ganglion  cells,  but  it  can  be  shown  that  in  spinal 
ganglia  the  single  pole  of  unipolar  ganglion  cells  consists  in  reality  of 

1  Other  details  of  the  structure  of  muscle,  and  more  especially  the  mode  of  the 
termination  of  the  nerves  in  muscle,  will  be  described  in  treating  of  the  functions 
of  muscular  fibre. 


Fig.  173. — Various  forms  of  nerve-cells,  a,  multi- 
polar, from  grey  matter  of  spinal  cord ;  b,  d,  bi- 
polar, from  ganglia  on  posterior  roots  of  spinal 
nerves ;  c,  </,  unipolar  (?),  from  cerebellum ;  g,  shovfs 
indications  of  a  process  coming  off  at  lovrer  end  ; 
e,  union  of  three  multipular  cells  in  spinal  cord  ;  /, 
union  of  three  tripolar,  or  pyramidal,  cells  in  grey 
matter  of  central  hemispheres. 


314 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


two  poles,  which  run  from  the  cell  in  the  same  direction,  and  then 
generally  they  turn  away  from  each  other  at  right  angles.  Such  cells 
are  termed  cells  with  T-shaped  fibres.  Ganglion  cells,  which  are  apolar, 
and  consequently  have  no  poles,  are  either  embryonic,  or  are  artificial 
pi'oductions  resulting  from  the  tearing  asunder  of  the  })oles  by  the  isolat- 
ing process.  Every  ganglion  cell  consists  of  a  granular  or  delicately 
striped  protoplasm,  Avhich  not  infrequently  contains  yellowish-brown 
pigment  granules  (Fig.  174,  A)  and  a  vesicle-shaped  nucleus,  which 
encloses  a  nucleolus  of  considerable  size.  This  nucleus  is  characteristic 
of  ganglion  cells.  The  cell-wall  is  absent.  Ganglion  cells  occur  in  the 
central  nerve  system  and  in  the  sj^mpathetic  ganglia  ;  they  occur  also  in 
both  cerebro-spinal  and  sympathetic  nerve  fibres. 


Fio.  174. — Various  forms  of  ganglion  cells,  a,  A,  spherical  uni- 
polar ganglion  cells  from  the  Gasserian  ganglion  of  the  fifth 
cranial  nerve  of  man.  (Method  No.  27,  Appendix.)  a  x  80  d., 
A  X  240  d.  Only  two  cells  show  \>o\&i,f;  the  two  other  cells  are 
surrounded  by  a  covering  containing  a  nucleus,  h.  b,  spindle- 
shaped  ;  c,  multipolar  ganglion  cells  from  the  spinal  cord  of  an 
ox,  X  80  d.  (Method  No.  28,  Aj)pendix.)  d,  multipolar 
ganglion  cells  (those  of  Purkinje)  from  the  cortex  of  the  cere- 
bellum of  man.  (Method  No.  29,  Appendix.)  d  x  SO  d. 
JO,  poles  of  protoplasm ;  ax,  axis  cylinder  pole.  The  nuclei  of 
6,  c,  and  d,  have,  by  the  method  employed  in  preparing  them, 
lost  their  characteristic  form. 

A  connection  of  the  ganglion  cells  occurs  in  such  a  manner  that  a 
network  of  fibrils  is  formed  by  the  protoplasmic  poles  of  several  ganglion 
cells. 

Closely  related  to  nerve  cells  are  the  nerve  fibres.  These  may  be 
here  described,  although  their  cellular  nature  is  still  the  subject  of 
controversy. 

8.  Nerve   Fibres    occur  in  tAvo    forms,  designated  as   (a)  medul- 


STRUCTURE  OF  CELLS  AND  CELLULAR  TISSUES.        315 


apparently   homogeneous,    faintly 


lated,  and  (b)  non-medullated  nerve  fibres.  The  two  forms  are  not 
to  be  regarded  as  sharply  separated  locally  or  generically.  It  is 
quite  a  usual  phenomenon  for  one  and  the  same  nerve  fibre  to  be,  in 
the  beginning  of  its  course,  medullated,  and  towards  the  end  of  its 
course  non-medullated. 

(a)  Medullated  Nerve  Fibres  are 
shining  fibres,  from  1  to  20  /x  in 
thickness.  The  most  important  part 
is  a  fine  elastic  cylindrical  fibre 
traversing  the  axis  of  the  fibres. 
This  is  called  the  axis  cylinder  of 
Purkinje,  or  the  band  of  Remak  (Fig. 
175).  Delicate  longitudinal  stripes, 
which  are  sometimes  observable  on 
it,  are  the  expression  of  the  fact 
that  the  axis  cylinder  may  be  com- 
posed of  fine  fibrils ;  a  very  notice- 
able transverse  striping  (Fig.  176), 
which  becomes  visil)le  after  treat- 
ment with  a  solution  of  nitrate  of 
silver,  has  not  yet  been  clearly 
explained.  The  axis  cylinder  is  sur- 
rounded by  the  sheath  of  the  marrow,  or  the  tvhite  substance  of  Schtoann, 
This  consists  of  a  fluid,   strongly-refractive,  fat-like  substance  called 

A     la  B  c 


-Tc 


Fig.  175. — Nerves,  c,  ordinary-sized  nerve 
fibre,  showing  axis  cylinder  surrounded  by 
white  substance  ;  d,  smaller  nerve  iibre, 
with  white  substance  scarcely  visible  ;  /, 
varicose  nerve  fibre,  from  grey  matter  near 
surface  of  cerebrum  ;  o,  nerve  fibre,  stained 
by  perosmic  acid,  showing  one  of  the  nodes 
of  Kanvier,  or  complete  hiterruptiou  of  the 
white  substance  ;  b,  nerve  fibre,  showing 
nucleus  and  node  of  Ranvier  (the  axis  cylin- 
der is  blackened  by  the  action  of  perosmic 
acid) ;  g,  non-medullated  nerve  fibres  from 
sympathetic,  having  no  white  substance, 
and  nucleated  at  intervals  :  c,  smallest  fibre. 


2       .? 

Fig.  176. — Medullated  nerve  fibres,  from  the  sciatic  of  the  frog,  x  240  d.  i,  f,  3,  Fresh 
with  solution  of  common  salt.  (Method  No.  30,  Appendix.)  3,  fibre  with  constrictions,  r ; 
U,  nerve  fibres  under  the  inflijence  of  water.  (Method  No.  31,  Appendix.)  5,  nerve  fibre 
treated  with  absolute  alcohol.  (Method  No.  32,  Appendix.)  »>.,  coagulated  marrow  ;  a, 
axis  cylinder.  B  and  C,  medullated  nerve  fibres  cif  the  rabbit,  X  5(i0d.  6,  Fresh  ;  c,  cylin- 
dro-conical  segments.  7,  S,  Hardened.  (Method  No.  33,  Appendix.)  «,  Axis  cylinder  ; 
6,  biconical  swelling  ;  r,  constriction  ;  w,  white  substance  coagulated  and  lifted  off  from 
s,  Schwann's  sheath  \'k',  nucleus  of  the  endoneurium. 


:M{y 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


Fig.  177.— MeduUated  nerve  fibres 
of  the  frog  treated  with  .sohition  of 
uitrate  of  silver,  x  5(30  d.  1.  -/•, 
nodes;  a,  axis  cylinder  blackened 
only  to  a  slight  extent ;  6,  bicoiii- 
cal  turgescence  caused  by  the  axis 
cylinder  being  squeezed  in  the 
isolation  process.  2.  a,  ax  is  cylin- 
der in  situ  blackened  only  to  a 
slight  extent.  3.  axis  cylinder 
with  transverse  striping.  The 
axis  cylinder  is  not  visible  in  the 
case  of  3.  (Method  No.  34,  Appen- 
dix.) 


myelin.  Under  favourable  circumstances,  we  perceive  that  the  \vhite 
substance  is  not  continuous,  but  is  divided  at  somewhat  irregular  dis- 
tances into  cylindro-conical  segments  by 
means  of  oblique  incisions  or  grooves  {Lan- 
termann^s  Notches,  Fig.  176,  Z»). 

The  centx'al  band,  which,  during  life,  is  quite 
homogeneous,  experiences,  after  death  and 
when  different  reagents  have  been  added  to 
it,  a  structural  metamorphosis.  At  the  begin- 
ning, the  nerve  fibre  possesses  a  double  con- 
tour ;  at  a  later  period,  the  central  band  or 
marrow  may  be  broken  up  into  small  globular 
masses.  The  sheath  of  the  white  substance 
is  a  delicate  structureless  cuticle,  known  as 
Schuxinn's  sheath  or  neurilemma.  On  the 
inner  surface  of  the  sheath,  prolate  spher- 
oidal nuclei  may  be  seen  surrounded  by  a 
small  quantity  of  protoplasm.  At  regular  dis- 
tances, constrictions  are  observed  where  the 
white  substance  is  wanting,  so  that  the  axis 
cylinder  and  Schwann's  sheath  come  into  contact.  These  constrictions 
are  known  as  nodes,  or  the  nodes  of  Ramier.     The  axis  cylinder  shows  a 

biconical  swelling  in  the  neighbourhood 
of  the  nodes.  Treatment  with  solu- 
tions of  nitrate  of  silver  shows  also 
cement  substance  on  the  nodes  (Fig. 
177,  r).  Every  medullated  fibre  is 
provided  Anth  nodes,  which,  being  ar- 
ranged at  regular  intervals,  divide  it 
into  interannular  segments. 

Medullated  nerve  fibres  occur  in  the 
roots  and  branches  of  the  cerebro-spinal 
nerves,  but  they  are  also  present  in  the 
sympathetic  nerves.     At  a  subsequent 
"   y  .      '  stage,  they  appear   in  the  brain  and 

spinal  cord,  Avhere  they  lose  Schwann's 

Fig.  17S.— Teazed  preparation  of  the  sym- 

pathetic  nerve  of  a  rabbit,  x  240  d.   1,  sheath.     ihc  thickness  01  a  nerve  fibre 

Non-medullated ;  2,  thin  meduUated  nerve  ,       .  .  - 

fibres  ;  3,  ganirlion  cells ;  the  characteristic    AVarrantS  nO  COllclUSlOn  With  respect  tO 

appearance  of  the  large  nuclei  has  been  lost    . ,  ,  ,.,  .  ^ , 

by  the  action  of  the  osmic  acid  used  in  its  motor  or  seusory  qualities  ;  On  the 
ne^cViv«tlssurfibres!^5°"deUcate''conLcti?e  Other  hand,  it  is  established  that  the 

tissue  fibres.     The  protoplasm  surrounding    r.-,  •  •       xi.  •   i 

the  nuclei  of  the  pale  nerve  fibres  is  not  fibres  increase  in  thicloiess  in  propor- 
<tiS^od5f35.%^pen"dig^^''^^    ^°"""-  tion   to   the   length    of    their    coiu-se. 


STRUCTURE  OF  CELLS  AND  CELLULAR  TISSUES.        317 

Division  of  the  medullated  nerves  first  takes  place  at  their  peripheral 
end.  The  medullated  nerve  fibres  have  a  limited  duration  of  life. 
They  degenerate;  the  white  substance  and  the  axis  cylinder  gradually 
become  granular,  and  the  granular  mass  is  rich  in  nuclei.  Out  of  this 
granular  mass,  white  substance  and  axis  cylinders  are  again  developed. 
(b)  The  non-meduHated,  pcde,  or  grey  nerve  fibres,  sometimes  also  termed 
Bemak's  nerve  fibres,  are  translucent,  delicate  longitudinally  striped  fibres 
of  variable  thickness.  They  consist  of  delicate  fibrils  and  of  nuclei, 
which,  surrounded  by  a  small  quantity  of  protoplasm,  lie  at  certain 
intervals  on  the  upper  surface  of  the  fibres.  The  non-meduUated  fibres 
are  found  in  the  central  nerve  system,  in  the  terminal  extensions  of 
the  cerebro-spinal  nerves,  and  especially  in  the  sympathetic  nerve  sys- 
tem. They  do  not  run  near  each  other  without  joining  neighbouring 
fibres,  as  the  medullated  nerve  fibres  do,  but  they  divide  and  again 
unite  so  as  to  form  elongated  meshes  by  anastomosis. 


Chap.  IX.— THE  PHYSIOLOGICAL  PROPERTIES  OF  EPITHELIUM. 

Epithelium  consists,  as  seen  in  Chap.  VIII.,  of  one  or  more  layers  of 
actively-growing  cells  on  one  surface  of  a  homogeneous  membrane  : 
numerous  blood-vessels  ramify  on  the  other  surface.  The  term  endothelium 
has  been  applied  to  the  lining  membrane  of  the  shut  cavities  of  the  body, 
such  as  the  pleura,  peritoneum,  etc.  Epithelial  cells  may  be  either  spheri- 
cal, irregularly  cylindrical,  polyhedral,  or  flattened  in  form.  They  may 
exist  in  one  or  more  layers,  and  they  appear  to  be  cemented  together  by 
some  kind  of  intermediate  substance.  When  the  cells  are  flattened,  irregu- 
lar in  form,  and  exist  in  a  single  layer,  as  in  the  pleura  and  peritoneum, 
the  intermediate  substance  is  demonstrable  by  the  action  of  certain 
reagents,  especially  a  solution  of  nitrate  of  silver,  which,  when  applied 
in  certain  conditions,  blackens  the  intercellular  matter.  The  following 
varieties  of  epithelium  are  met  with  in  the  body — 

1.  Simple,  flat,  squamous,  or  tesselated  epithelium,  in  which  there  is 
scarcely  more  than  a  single  layer  of  developed  cells,  such  as  is  observed 
on  the  internal  surfaces  of  the  serous  and  synovial  membranes,  and  on 
those  of  the  heart,  blood-vessels,  and  absorbent  vessels.  This  includes 
the  variety  termed  endothelium. 

2.  Laminar  or  stratified  epithelium,  consisting  of  a  number  of  flattened 
cells,  usually  in  various  stages  of  alteration,  such  as  exist  in  the 
epidermis  and  on  the  mucous  membranes  near  the  entrance  of  the 
alimentary  and  genito-urinary  passages.  Nails,  hair,  and  horns  are 
modifications  of  this  texture. 


tnS  THE  PHYSIOLOaV  OF  THE  TISSUES. 

3.  Colnmnar  or  pritunatic  epithelium,  consisting  of  a  single  layer  of 
<-'longated  nneleated  cells  ;  below  these,  however,  are  in  general  seen 
others  of  a  more  spherical  shape,  Avhich  are,  in  fact,  the  columnar 
particles  in  an  earlier  stage  of  groAvth.  Such  is  the  structure  lining  the 
whole  alimentar}'  canal,  from  the  stomach  downwards,  and  also  part  of 
the  ducts  of  secreting  glands. 

4.  Spheroidal  epithelium  may  be  regarded  almost  as  belonging  to  the 
last  mentioned  form  ;  it  constitutes,  in  some  places,  a  transition  form 
between  the  columnar  and  tesselated  varieties  ;  it  is  best  seen  in  the 
urethra,  ureters,  and  pelvis  of  the  kidney,  and  also  in  the  ducts  of  the 
mamma,  and  of  the  cutaneous  and  some  other  glands. 

5.  Ciliated  epithelium  is  generally  of  the  columnar  form,  and  consists 
of  nucleated  cells,  upon  the  free  surface  or  ends  of  which  minute  micro- 
scopic hair-like  projections  or  cilia  are  placed,  which,  when  covered 
Avith  fluid,  move  with  great  rapidity.  This  kind  of  epithelium  lines  all 
the  air  passages,  and  the  cavities  and  passages  communicating  with 
them,  such  as  the  nasal  ducts,  the  conjunctiva  of  the  eyelids,  the  sinuses 
opening  into  the  nasal  passages,  the  Eustachian  tube  and  tympanum, 
part  of  the  soft  palate  and  pharynx  ;  also  the  uterus  and  Fallopian 
tubes,  and  the  ventricles  of  the  brain. 

Each  of  these  forms  of  epithelium  has  a  special  function.  Tesselated 
epithelium  covers  an  extensive  surface  for  protective  or  absorptive  pur- 
poses ;  columnar  epitheliiim  has  numerous  cellular  elements  on  a  surface 
of  limited  extent,  so  as  to  permit  great  nutritive  vitality;  stratified 
epithelium,  from  the  abundance  of  cells,  admits  of  the  rapid  growth  and 
shedding  of  these  for  functional  purposes ;  and  ciliated  epithelium 
maintains  vibratile  movement. 

Epithelium  forms  a  continuous  layer  over  the  surface  of  the  body, 
and  lines  all  the  internal  passages  and  cavities.  This  fact  is  of 
physiological  importance,  inasmuch  as  it  indicates  that  all  substances 
entering  or  leaving  the  body  must,  in  some  Avay  or  other,  pass  through 
an  epithelial  layer. 

1.  Physical  Properties  of  Epithelium. — Where  epithelium  is  exposed  to 
pressure  and  other  external  influences,  it  becomes  more  or  less  hard  and 
firm,  as  may  be  seen  in  the  nails,  in  the  epidermis  covering  the  palms 
of  the  hands  and  soles  of  the  feet,  in  "  corns,"  and  in  the  callosities 
which  appear  on  the  hands  of  those  performing  much  manual  labour. 
The  columnar  epithelium  of  the  intestinal  canal  is,  on  the  contrary,  soft 
and  easily  detached.  The  cohesion  of  epithelium  is  usually  feeble,  but 
.such  structures  as  the  epidermis  may  sustain  considerable  distension 
without  rupture,  as  may  be  seen  over  large  abdominal  tumours.  Elas- 
ticity is  very  imperfect.     An  epithelial  layer  is  a  bad  conductor  of  heat 


PHYSIOLOGICAL  PROPERTIES  OF  EPITHELIUM.        319 

and  electricity.  The  hairy  covering  of  many  species  of  animals,  and 
the  feathery  covering  of  birds,  by  diminishing  the  amount  of  heat  lost 
by  radiation  from  the  surface,  assist  in  maintaining  the  temperatiure  of 
the  body.  Epidermis  absorbs  water  with  great  rapidity,  except  where 
it  is  covered  by  a  thin  layer  of  oily  matter. 

2.  Vital  Properties  of  Epithelium. — The  nutrition  of  an  epithelial  layer 
depends  upon  the  transudation  of  nutrient  fluid  from  the  blood-vessels 
underneath  the  layer  of  cells.  It  is  usually  very  active,  except  perhaps 
in  stratified  epithelium.  Most  epithelial  cells  are  constantly  engaged 
in  the  formation  of  particular  jDroximate  principles.  This  is  especially 
true  of  spheroidal  epithelium,  in  the  cells  of  which  various  substances, 
such  as  ptyalin,  pepsin,  etc.,  are  formed.  In  some  epithelial  cells, 
chemical  transformations  apparently  take  place.  Thus,  the  superficial 
layers  of  the  epidermis  undergo  changes  which  so  alter  the  cells  as  to 
render  them  insusceptible  to  the  action  of  acetic  acid,  while,  in  the 
deeper  cells  of  the  same  layer,  pigment  may  be  formed.  The  exact 
mode  of  development  of  epithelial  cells  is  still  unknown,  but  there 
appears  to  be  an  incessant  development  of  new  cells  from  the  surface  of 
the  membrane  on  which  the  deeper  layer  is  situated.  The  new  cells 
gradually  pass  outwards,  and  on  reaching  the  superficial  layer,  last  for 
a  certain  time  and  then  drop  ofi".  This  process  of  desquamation,  as 
already  stated,  is  preceded  by  chemical  transformation.  There  is  thus 
a  constant  elimination  from  the  body  of  the  materials  which  form 
epithelial  cells. 

Epithelial  tissue  is  not  sensitive,  but  in  the  structure  of  the  terminal 
organs  of  sense,  epithelial  cells  may  be  modified  for  special  purposes,  as 
Avill  be  illustrated  in  treating  of  these  organs. 

3.  Influence  of  Epithelium  in  Absorption  and  Elimination. — The  function 
of  epithelium  in  the  process  of  absorption,  or  the  introduction  of  matter 
from  the  external  medium  into  the  fluids  or  tissues  of  the  body,  may  be 
briefly  stated  as  follows — 

(1)  Absorption  of  Gases  and  Volatile  Substances. — The  pulmonary  surface 
in  the  ultimate  air  cells  of  the  lung,  which  is  covered  by  a  thin  layer  of 
flattened  epithelial  cells,  absorbs  oxygen  and  volatile  matters.  The 
surface  of  the  skin,  and  perhaps  also  the  intestinal  mucous  surface, 
absorb  small  quantities  of  gases. 

(2)  Absorption  of  Fluids  and  Soluble  Substances. — All  ejaithelial  surfaces 
may  absorb  water,  or  solutions  of  salts  or  other  substances,  but  there 
are  great  difi'erences  in  this  respect.  Thus,  the  pulmonary  mucous 
membrane  absorbs  water  freely ;  the  epithelial  lining  of  the  bladder 
scarcely  absorbs  it  at  all ;  while  the  intestinal  mucous  membrane  per- 
mits readily  the  passage  of  water  and  of  soluble  matters.     In  certain 


320  THE  PHTSIOLOGV  OF  THE  TISSUES. 

circumstances,  also,  the  epidermis  covering  the  skin  may  permit  the 
absorption  of  water. 

(3)  Ahsorption  of  Fat. — The  cylindrical  or  columnar  epithelium  of  the 
lining  of  the  small  intestine  absorbs  fat  by  a  process  the  mechanism  of 
which  will  be  described  in  treating  of  intestinal  absorption. 

(4)  Injimnce  of  Epithelium  in  Elimination. — The  elimination  of  matters 
from  the  body  may  take  place  either  by  exhalation  of  watery  vapour, 
of  various  gases,  or  of  volatile  substances,  from  epithelial  surfaces,  or 
by  a  true  process  of  secretion,  in  which  the  spheroidal  epithelial  cells 
lining  the  ultimate  pouches  of  glands  constitute  the  active  agents.  The 
process  of  secretion  is  a  mode  of  activity  of  glandular  epithelium. 

4.  Ciliated  Epithelium. — Epithelial  cells,  on  which  cilia  are  placed,  are 
generally  of  the  columnar,  sometimes  of  the  spheroidal,  rarely  of  the 
flat  kind.  These  bodies  constitute  minute  hair-like  processes,  attached 
to,  or  forming  a  prolongation  of,  the  wall  of  the  cell  at  its  free  side,  and 
when  covered  -n-ith  fluid,  are  in  constant  "sabratory  motion. 

Ciliated  epithelip.l  cells  do  not  differ  materially  from  other  cells  of  the 
same  form,  excepting  in  the  possession  of  the  cilia ;  they  usually  con- 
tain distinct  nuclei ;  and  they  appear  to  be  abraded  from  the  surfaces 
on  which  they  are  situated,  and  to  be  replaced  by  successive  layers  of 
new  cells,  formed  from  the  subjacent  texture,  and  subsequently  acquir- 
ing the  ciliated  structure  when  they  reach  the  surface. 

The  number  of  cilia  attached  to  each  cell  is  subject  to  considerable 
variety.  In  some  instances,  only  one  or  two ;  in  others,  a  crown  or 
circle  of  numerous  cilia  occupies  the  free  surface  of  the  cells. 

The  individual  cilia  are,  in  the  human  subject,  generally  from 
8  /A  to  4  /x.  in  length  ;  in  invertebrata,  they  are  often  consider- 
ably longer.  They  are  also  proportionately  thicker  and  blunter  in 
A'Crtebrate  than  in  invertebrate  animals. 

Ciliated  epithelium  occurs  in  the  human  body  in  the  following 
situations,  some  of  which  have  been  already  mentioned,  p.  303 — 
1st,  on  the  mucous  membrane  of  the  air-passages,  and  the 
various  sinuses  and  tubes  communicating  immediately  ■with  them,  as  in 
the  nares  (excepting  close  to  their  external  openings) ;  part  of  the  soft 
palate,  upper  and  lateral  part  of  the  pharynx.  Eustachian  tube,  frontal, 
maxillary,  sphenoidal,  and  ethmoidal  sinuses ;  on  the  conjunctiva  pal- 
pebrarum, lachrymal  sacs  and  nasal  ducts ;  on  the  mucous  lining  of  the 
larynx,  trachea,  and  bronchia,  as  far  as  their  fine  subdi\dsions,  but  not 
extending  into  the  air-cells  of  the  lungs  :  2nd,  in  the  adult  female,  the 
epithelium  is  ciliated  in  the  lining  membrane  of  the  uterus.  Fallopian 
tubes,  and  their  fimbriated  margins  :  and  3rd,  in  the  membrane  lining 


PHYSIOLOGICAL  PROPERTIES  OF  EPITHELIUM.        321 

the  ventricles  of  the  brain,  the  cells  have  been  observed  to  be  of  a 
ciliated  kind. 

Ciliary  Motion, 

The  movement  of  each  cilium  is  most  commonly  of  a  folding  or 
lashing  kind.  That  of  the  whole  set  of  cilia,  covering  a  membranous 
surface,  shows  the  passage  of  successive  waves,  somewhat  in  the  same 
manner  as  different  parts  of  the  crop  in  a  field  of  wheat  are  repeatedly 
bent  in  succession  by  the  wind  passing  over  it.  ^ATien  the  ciliary 
motion  is  active,  the  movement  is  so  rapid  that  the  optical  effect  is 
the  appearance  of  a  stream  of  fluid  flowing  along  the  surface.  This  is 
the  case  especially  when  we  look  at  a  marginal  line  of  cilia,  as  in  the 
gills  of  a  common  mussel. 

Four  varieties  of  ciliary  motion  may  be  noticed — (1)  the  hook-like,  in 
which  each  cilium  makes  the  movement  of  a  finger  which  is  alternately 
bent  and  extended ;  (2)  the  funnel-shapecl,  in  which  the  upper  portion  of 
the  hair  describes  a  circle  in  swinging,  and  the  whole  a  cone,  whose 
apex  is  formed  by  the  firmly-attached  base  of  the  cilium;  (3)  the 
oscillating,  in  which  the  whole  hair  sways  more  like  a  pendulum,  from 
side  to  side ;  and  (4)  the  undulathvj,  when  the  hair  executes  a  move- 
ment like  the  lash  of  a  whip  moderately  wielded,  or  that  of  the  tail  of 
a  spermatozoon.  Of  all  these  forms  of  ciliary  motion,  the  first  appears 
to  be  by  far  the  most  frequent. 

Ciliary  movement  is  independent,  so  far  as  mere  movement  is  con- 
cerned, of  the  circulatory  and  nervous  systems ;  although,  no  doubt, 
these  must  affect  its  nutrition.  Elevation  of  temperature  up  to 
about  40°  C  increases  the  movement,  when  it  ceases,  probably  from 
coagulation  of  the  protoplasm  in  the  cilia.  Cold  retards  the  movement. 
All  substances  having  a  chemical  action  on  protoplasm,  if  applied  in 
solutions  of  sufficient  strength,  stop  ciliary  action.  Thus,  water 
accelerates  the  movement  at  first,  but  soon  stops  it,  probably  by  acting 
on  the  protoplasm.  As  a  rule,  fresh  water  stops  ciliary  motion  in  parts 
removed  from  inhabitants  of  salt  water.  Bile,  acids,  alkalies,  and 
alcohol,  if  of  sufficient  strength,  stop  ciliary  action;  but,  if  in  weak 
solutions,  they  may  accelerate  the  movement.  Ciliary  movement 
requires  the  presence  of  oxygen,  while  the  presence  of  carbonic  acid 
seems  to  have  a  retarding  influence.  Cilia  may  be  arrested  by  the 
action  of  chloroform  or  ether,  and  it  is  interesting  to  observe  that  they 
may  recover  from  the  influence  of  these  substances.  Electricity, 
whether  applied  as  a  continuous  current,  or  from  an  induction  coil,  • 
produces  no  appreciable  effect. 

Ciliary  movement  continues  for  a  short  time  in  small  detached  por- 

I.  X 


322  THE  PHYSIOLOGY  OF  THE  TISSUES. 

tions  of  the  texture,  and  foi'  a  longer  period  in  the  entire  part,  after  the 
destruction  of  the  brain  and  spinal  marrow,  or  after  the  first  invasion 
of  apparent  death.  The  time  of  this  persistence  varies  from  a  few 
hours  to  several  days  in  man  and  warm-blooded  animals,  and  is  even 
considerably  longer  in  cold-blooded  reptiles ;  it  is  much  influenced  by 
temperature,  the  nature  of  the  fluids  in  contact  with  the  texture,  and 
other  circumstances. 

Various  theories  have  been  advanced  to  explain  the  action  of  cilia. 
The  most  probable  is  that  it  is  due  to  the  property  of  contractility 
inherent  in  protoplasm.  As  Engelmann  suggests,  we  may  suppose  the 
contractile  protoplasm  to  be  chiefly  on  the  concave  side  of  a  curved 
cilium,  so  that,  on  contraction,  the  cilium  will  be  brought  downwards, 
and  on  the  contractile  motion  ceasing,  the  cilium  may  be  erected  by  an 
elastic  recoil  of  the  substance  forming  its  convex  border.  That  ciliary 
movement  is  dependent  on  nutritional  changes  occurring  in  the  cell 
■with  which  the  cilium  is  connected  is  proved  by  the  fact  that  if  the 
cilium  has  its  connection  with  the  cell  severed,  all  movement  ceases, 
and  if  a  cilium  is  cut  into  two  fragments,  only  the  fragment  moves  that 
is  still  connected  with  the  cell. 

Chap.  X.— THE  INTERCELLULAR  SUBSTANCE. 

In  the  early  embryonic  period,  the  animal  body  consists  entirely  of 
cells,  while  later  on,  a  smaller  or  larger  quantity  of  unformed  or  formed 
intermediary  substance  is  found  between  the  cells.  This  intercellular 
substance  is  formed  by  the  cells,  and  it  may  be  regarded  either  as  a 
secretion  of  the  cells  or  as  arising  from  a  transformation  of  the  peripheral 
layers  of  the  protoplasm  of  the  cell.  In  certain  cases  there  may  be  a 
total  metamorphosis  of  the  cells.  It  is  very  difiicult  to  come  to  an  opinion 
as  to  the  mode  of  formation  of  individual  intercellular  substances,  and 
there  are  many  points  regarding  the  formation  of  intercellular  matter 
that  are  still  the  subject  of  controversy. 

When  the  intercellular  matter  exists  in  small  quantities,  it  is  called 
cement  substance,  as  we  find  it  existing  between  epithelial  cells,  connective 
tissue  cells,  smooth  muscular  fibres,  etc.,  but  when  the  intercellular 
substance  appears  in  larger  quantities,  surpassing  the  mass  of  the  cells, 
it  is  then  termed  ground  substance  or  matrix.  The  ground  substance  is 
either  amorphous,  as  in  the  jelly-like  ground  substance  of  the  tissue  of 
the  umbilical  cord,  or  it  possesses  a  definite  shape,  when  it  may  be 
termed  formed  ground  substance. 

There  are  the  following  varieties  of  tissue  in  which  the  ground  sub- 
stance or  matrix  assumes  a  definite  form — 


THE  INTERCELLULAR  SUBSTANCE. 


323 


(1)  The  Gh-ound  Substance  of  Connective  Tissue. — The  elements  of  this 
substance  are  the  connective  tissue  fibrils, 
threads  of  the  utmost  degree  of  fineness, 
which  are  bound  so  as  to  form  bundles  of 
various  degrees  of  thickness  (termed  the 
connective  tissue  bundles),  by  means  of  a 
small  amount  of  unformed  cement  sub- 
stance. These  bundles  are  soft,  flexible, 
possessed  of  little  elasticity,  and  they  are 
specially  characterized  by  their  pale  out- 
lines, longitudinal  striation,  and  their  wavy 
course.  The  bundles  on  treatment  with 
picric  acid  split  into  fibrils ;  on  the  addi- 
tion of  diluted  acids,  as,  for  example,  acetic   connective     tissue  "  from     the     inter- 

^  muscular  connective    tissue    of    man, 

acid,  they  become  completely  transparent,  x  240  d.   (Method  No.  36,  Appendix.) 
Alkaline  fluids  destroy  them,  and  when  boiled,  they  yield  gelatin. 

When  connective  tissue  comes  into  contact  with  an  epithelial  layer,  it 
not  infrequently  assumes  the  form  of  a  structureless  membrane,  termed 
a  basement  membrane,  or  membrana  propria.  In  some  cases,  as  in  the 
salivary  glands,  the  membrana  propria  consists,  not  of  the  structure- 
less membrane,  but  of  a  membrane  composed  of  a  layer  of  flattened 
nucleated  cells. 


Fig.  179. — Variously  thick  bundles  of 


M^=JX 


"°Ocf 


'cV5^  %J 


Fig.  180. — Elastic  fibres,  X  560  d.  A,  delicate  elastic  fibres  ;  (/)  from  the  intermuscular  connective 
tissue  of  man  ;  (6)  bundles  of  connective  tissue,  swollen  and  gelatinous  after  addition  of  acetic 
acid.  (Method  No.  37,  Appendix.)  £,  very  thick  elastic  fibres  ;  (/)  from  the  ligamentum  nuchse 
of  the  ox  ;  (6)  bundles  of  connective  tissue.  (Method  No.  38,  Appendix.)  C,  from  a  transverse 
section  of  the  ligamentum  nuchae  of  the  ox.  (/)  elastic  fibres ;  (6)  bundles  of  connective  tissue. 
(Method  No.  39,  Appendix.) 

The  Matrix  of  Hyaline  Cartilage  may  also  be  regarded  as  formed  of 
the  same  material  as  constitutes  the  matrix  of  fibrillated  connective 


324  THE  PHYSIOLOGY  OF  THE  TISSUES. 

tissue.  The  matrix  of  hyaline  cartilage,  by  the  usual  methods  of  in- 
vestigation, appears  structureless  and  homogeneous,  but  by  certain 
methods,  such  as  artificial  digestion,  it  may  be  caused  to  split  up  into 
bundles  of  fibres.  The  behaviour  of  the  matrix  of  cartilage  to  polarized 
light  also  indicates  a  fibrillar  structure.  The  matrix  of  cartilage  is  firm 
and  highly  elastic ;  on  boiling  it  yields  chondrin. 

(2)  The  Matrix  of  Bone  consists  of  fibrils  impregnated  mth  salts 
of  lime,  especially  the  basicphosphate  of  lime,  giving  the  bone  a  great 
degree  of  firmness  and  hardness.  The  matrix  of  dentine  of  tooth  re- 
sembles  that  of  bone,  but  is  still  harder. 

(3)  The  Elastic  Substance :  its  structural  form  is  the  elastic  fibre  (Fig. 
180)  which  is  characterized  by  its  sharp  dark  outlines,  its  strong  power 
of  refraction,  and  its  marked  resistance  to  acids  and  alkalies.      The 

elastic  fibres  vary  in  thickness  (up  to 

4y/y  11  /^)  and  appear  sometimes  in  th& 

form  of  finer  or  coarser  reticulations,. 

which  are  sometimes  narrow-meshed, 

and    at    other    times,   wide-meshed. 

Narrow-meshed   reticulations    woven 

out  of  thick  elastic  fibres  constitute 

'^    k     .-^QiO^^dh      transitional  forms  passing  into  e/asifzc 

;;^V^(  \^ffifihf'\     membranes  (Fig.  181),  which,  whether 

^f  ..    ,  X  J     X     T        ^^  +1,-  1    homogeneous   or   delicately  striated, 

Fio.  ISl.— Reticulated  network,  n,  of  thick  o  . 

elastic  fibres,  becoming  on  the  left  hand  ^^.q  penetrated  bv  holes  of  VarioUS- 
m,  a  fenestrated  membrane,    or  membrane  ■•■  '' 

having  numerous  perforations  or  holes.  From  gizes.  Such  membranes  are  SOme- 
the  endocardium  of  man,  x  560  d.     (Method  111.7 

No.  40,  Appendix.)  timcs   Called  wmdowed  or  jenestrated 

membranes,  and  they  are  no  doubt  produced  by  the  blending  or  union 
of  very  broad  elastic  bands  or  fibres. 

Lastly,  cuticidar  formations  are  to  be  classed  along  with  the  inter- 
cellular substances.  These  are  genuine  secretions  occurring  on  the  upper 
surface  of  the  cells. 


Chap.  XI.— THE  STRUCTURE  OF  THE  CONNECTIVE  TISSUES. 

The  connective  tissues  include  (1)  connective  or  areolar  tissue,  (2) 
cartilage,  and  (3)  bone  and  the  dentine  of  the  teeth.  Although  these 
tissues  appear  on  a  superficial  examination  to  have  few  characters  in 
common,  a  study  of  their  development  and  of  their  histological  structure,, 
as  revealed  by  various  reagents,  indicates  that  they  belong  to  the  same-- 
o-roup.  They  have  a  common  origin  and  their  structure  is  of  the  same 
type.  Thus  they  all  originate  in  the  mesoblast.  They  consist  essentially 
of  cells  of  the  same  kind  lying  in  a  matrix  modified  in  character  accord 


STRUCTURE  OF  THE  CONNECTIVE  TISSUES.  325 


ing  to  the  tissue,  and  they  all  have  the  common  function  of  forming  the 
skeleton  or  framework  of  the  body,  and  the  material  by  which  all  the 
parts  of  the  body  are  bound  or  connected  together  and  by  which  support 
is  given  to  delicate  structures  in  many  organs.  Further,  their  relation- 
ship is  shown  by  the  fact  that  in  the  construction  of  the  bodies  of  some 
of  the  lower  vertebrate  forms,  the  connective  tissues  may  replace  each 
other,  so  that  a  portion  of  the  same  organ  may  be  cartilaginous  in  one 
group,  bony  in  a  second,  and  formed  of  fibrous  tissue  in  a  third. 

I.    The  Connective  Tissues  Proper. 

These  embrace  {a)  jelly-like  or  mucous  connective  tissue,  (5)  fibrillar 
tissue,  and  (c)  reticulated  connective  tissue. 

(ft)  Gelatinous,  Jelly-like,  w  Mucous  Connective  Tissue  consists  of  a  large 
quantity  of  structureless  intermediate  mucoid  substance,  enclosing 
delicate  bundles  of  connective  tissue 
and  also  containing  a  few  round  or 
stellate  cells.  In  the  higher  animals, 
it  occurs  only  in  the  umbilical  cord  of 
very  young  embryos,  but  it  is  widely 
diffused  in  the  lower  animals^  (Fig.  182). 

(6)  Fihrillar  Connective  Tissue  consists 
of  a  matrix  formed  of  fibrils.  It  also 
contains  cells  and  elastic  fibres.  The 
matrix  of  fibres  has  been  already 
shown  (p.  323).  There  exist  between 
the    bundles    of    connective    tissue, 

n  Ti  m      1   ii  J  •  tissue  iiiuiost  ounuuei' 

nssure-like  spaces,  called  the  connective  through  transversely." 
tissue  fissures,  or  lacunce,  filled  with  a  ^pp®"^  ^^■•' 
fluid  or  plasma.  These  lacunse  are  connected  with  the  lymphatic  system, 
and  they  may  be  regarded  as  the  beginning  of  this  system  in  the  loose 
connective  tissue.  The  cells  (Fig.  183,  A)  are  irregularly  polygonal, 
or  stellated,  strongly  flattened,  and  are  often  bent  or  fractured  in  various 
ways.  They  fit  into  the  narrow  spaces  between  the  bundles  of  con- 
nective tissue.  Stellate  connective  tissue  cells  not  infrequently  embrace 
a  bundle  of  connective  tissue  fibres.  If  we  treat  such  a  bundle  with  acetic 
acid,  it  swells  up  in  places  between  the  constrictions  of  the  cells,  and 
the  bundle  appears  to  have  a  fibre  twisted  round  it.  The  processes  of 
the  cells  were  at  one  time  taken  for  fibres,  and  they  were  called  spiral 
fibres  (Henle).    (Fig.  183,  B.)     Other  connective  tissue  cells  are  round, 

^  The  vitreous  humour  of  the  eye  is  often  erroneously  classed  iinder  the  head  of 
mucous  tissue.  The  reticulations  in  the  vitreous  humour  are  not  filled  with  jelly- 
like matter  but  with  fluid. 


Fig.  182. — From  a  transverse  section  of  the 
umbilical  cord  of  a  human  embryo  of  the 
fourth  month,  x  240  d.  1.  cells ;  2.  inter- 
mediary substance  ;  3.  bundle  of  connective 
tissue  almost  obliquely  cut ;  4.  bundle  cut 
(iMethod    No.   41, 


326 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


rich  in  protoplasm,  coarse-grained,  and  of  large  size.  (Waldeyer.)  These 
are  termed  plasm  cells,  and  they  are  found  in  the  \icinity  of  small  blood- 
vessels (Fig.  183,  C).  To 
the  like  category  belong 
the  fat  cells,  which  are 
conspicuous  for  their  facil- 
ity in  taking  up  colour 
when  treated  with  the 
aniline  dyes.  All  these 
cells  are  termed  fixed  or 
stationary  connective  tissue 
cells.  They  must  be  dis- 
tinguished from  the  ican- 
dering  or  migratory  cells, 
leucocytes,  resembling  the 

Fio.  183. — A.  1,  connective  tissue  from  intermuscular  con-  forms   which    likewise    OC- 

nective  tissue  ;   2,  brolien  cell ;  3,  cell,  whose  protoplasm  is 

invisible  ;  (b)  bundle  of  connective  tissue.      (Method  Xo.  42,  CUT     although    in    smaller 

Appendix.)    B.  bundle  of  connective  tissue  surrounded  by  a  '      .  . 

spiral  of  elongated  cells.    A-,  nucleus.  (Method  No.  43,  Appen-  quantity,  in    fibrillar    COn- 

dix.)    c,  plasma  cells  from  the  eyelid  of  a  child.      (Method  .  . 

No.  44,  Appendix.)  UectlVe  tlSSUC. 

Elastic  fibres  are  contained  in  almost  all  kinds  of  connective 
tissue. 

Fat  is  often  a  constituent  of  fibrillar  connective  tissue.  It  appears 
in  the  form  of  a  drop  in  the  flat  connective  tissue  cells,  and  changes 
these  into  fat  cells  {vide  above,  p.  305).  The  different  elements  of  fibril- 
lar connective  tissue  may  be  united  -vnthout  gi^ang  rise  to  structures  of 
definite  form,  formless  connective  tissue,  or  they  may  produce  a  definite 
shape  and  the  tissue  may  then  be  termed  fm-med  connective  tissue.  Form- 
less connective  tissue  is  conspicuous  for  the  looser  connection  and  more 
diversified  interlacing  of  the  bundles  of  connective  tissue.  It  occurs  be- 
tween neighlDouring  organs,  binding  these  together  and  filling  out  the 
intervals  between  them.  Hence  it  may  be  termed  aredlar  or  interstitial 
tissue.     The  cells  of  this  tissue  not  infrequently  contain  fat. 

Formed  connective  tissue  is  characterized  by  a  closer  connection  and  a 
more  regular  course  of  its  bundles.  To  this  variety  of  connective  tissue  be- 
long the  true  skin,  the  mucous  membranes,  serous  membranes,  the  compact 
coverings  of  the  nerve  system,  of  the  blood-A^essels,  of  the  eye,  of  many 
glands,  and  of  the  periosteum  and  perichondrium.  It  also  includes  the 
sinews  or  tendons,  fasciae,  and  fibrous  septa  or  aponeuroses. 

Tendons  are  characterized  by  the  parallel  course  of  the  fibres  forming 
them.  These  are  firmly  united.  Tendons  contain  very  few  elastic 
fibres.  A  tendon  is  composed  of  a  number  of  bundles  of  connective 
tissue  held  together  by  a  small  quantity  of  loose  connective  tissue. 


STRUCTURE  OF  TEE  CONNECTIVE  TISSUES. 


327 


Each  of  these  secondary  bundles  of  connective  tissue  is  formed  by  a 
number  of  fibrils  running  in  a  straight  line,  and  united  by  means  of  a 
small  quantity  of  cement  substance  to  the  smaller  primary  bundles. 
Between  the  primary  bundles  are  the  cellular  elements  of  tendon. 
These  are  flat  connective  tissue  cells  placed  in  a  row,  and,  as  they  are 
curved  like  a  hollow  tile,  they  partially  embrace  the  primary  bundles,  and 
unite  with  neighbouring  cells  by  means  of  flat  prolongations.  These  are 
termed  Banvier's  cells. 


A.  B. 

Fig.  184. — Fruu]  the  transverse  section  of  a  tendon  of  an  adult  man.  A.  x  80  d. 
s,  bundles  of  tendon  ;  b,  loose  connective  tissue  containing,  at  r/,  transverse 
sections  of  blood-vessels  ;  z,  cells.  (Method  No.  45,  Appendix.)  B.  x  240  d. 
p,  primary  bundles  embraced  by  prolongations  a,  of  the  cells,  :  ;  b,  loose  connec- 
tive tissue  ;  g,  transverse  sections  of  blood-vessels.     (Method  No.  4ti,  Appendix.) 

Elastic  fibres  are  present  in  great 
quantity  only  in  the  loose  connective 
tissue ;  in  the  bundles  of  connective 
tissue  in  tendon,  they  occur  only  spar- 
ingly in  the  form  of  delicate,  wide- 
meshed  reticulations.  The  blood- 
vessels in  tendons  are  contained  only 
in  loose  connective  tissue,  covering 
the  bundles ;  and  lymphatic  vessels  are 
principally  found  on  the  outer  surface 
of  tendons.  The  scanty  nerve  fibres 
are  non-medullated,  and  these  pass 
into  end-organs  resembling  the  motor- 
end-plates  in  muscular  fibre. 

The  fascice  are  composed  of  bundles 
of  connective  tissue  forming  an  irregular  meshwork. 


Fig.  185. — From  a  section  of  a 
human  lymphatic  gland  which 
has  been  shaken  in  fluid,  x  560  d. 
n,  reticulated  net-work  ;  z,  con- 
nective tissue  cells;  I,  leucocytes. 
(Method  No.  47,  Appendix.) 


328  THE  PHYSIOLOGY  OF  THE  TISSUES. 

The  ligaments  are  distinguished  from  tendons  only  by  their  more  or 
less  large  supply  of  elastic  fibres. 

White  fibrous  tissue  is  developed  from  certain  cells  primarily  derived 
from  the  mesoblast.  These  cells  are  at  first  spherical,  but  they  become 
elongated  and  spindle-shaped,  and  each  cell  contains  an  oval  nucleus. 
Each  cell  gives  rise  by  longitudinal  fibrillation  to  a  bundle  of  connective 
tissue  fibres,  and  the  nucleus  may  disappear.  It  would  appear  that  the 
primitive  cells  may  also  form  a  homogeneous  substance  around  them,  and 
that  fibres  may  arise  from  a  kind  of  cleavage  of  this  substance. 

Betkular  &r  Adenoid  Connective  Tissue. — Opinions  regarding  the 
structure  of  reticular  connective  tissue  are  much  divided.  According 
to  some,  it  consists  of  stellate  cells  Avhich  anastomose  by  their  processes 
and  thus  build  up  a  delicate  net-work.  This  notion  gave  rise  to  the 
term,  hjtogenous,  that  is  to  say,  a  tissue  formed  out  of  cells.^  According 
to  the  other  -view,  the  net-work  is  formed  only  of  fibres  of  connective 
tissue  to  which  flat  nucleated  cells  are  joined.  We  can  succeed 
in  demonstrating,  in  the  higher  vertebrates,  by  means  of  complicated 
methods,  the  contours  of  the  flat  cells  lying  on  the  fibres ;  but  the 
fact  is  that  fibrillar  connective  tissue  may,  even  in  the  case  of  adult 
tissue,  change  into  reticular  tissue.  The  circumstance  also  that  the 
adaptation  of  flat  cells  to  the  bundles  of  fibres  is  in  connective  tissue  a 
rule  almost  without  exception  is  much  in  favour  of  the  latter  \aew. 
The  meshes  of  the  reticular  connective  tissue  are  filled  with  leucocj- tes 
compactly  pressed  together.  Reticular  connective  tissue  having  the 
meshes  filled  with  leucocytes  occiurs  principally  in  Ijonphatic  glands. 
It  is  for  this  reason  termed  adenoid,  that  is,  gland-like  tissue.  It  is 
richly  supplied  with  blood-vessels  (Fig.  18.5). 

2.  Cartilage. 

Cartilage  is  firm,  elastic,  easily  cut,  of  a  milk-white  or  yello^^^sh 
colour,  and  consists  of  cells,  and  of  a  matrix  or  ground  substance.  The 
cells  exhibit  various  shapes.  They  are  usually  roundish  or  flattened. 
They  lie  in  cavities  in  the  matrix  which  they  completely  fill,  and 
they  are  surrounded  by  a  strongly  refracting,  sometimes  concentrically 
striated,  capsule,  the  cartilage  ca])sule.  The  matrix  is  either  of  the  same 
kind,  homogeneous,  or  interwoven  with  elastic  fibres,  or  it  is  formed  of  a 
fibrillated  connective  tissue.  In  accordance  ^vith.  this  general  view,  we 
distinguish  (a)  hyaline  cartilage,  (5)  elastic  or  j'ellow  fibro-cartilage,  and 
(c)  connective  tissue  or  white  fibro-cartilage. 

(a)  Hyaline  Cartilage  is  of  a  light-bluish  hue,  like  that  of  a  stain  of 

1  Mucous  tissue,  as  it  occurs  in  the  jelly  of  the  umbilical  cord,  might  also  be 
claimed  as  a  kytogenous  tissue. 


STRUCTURE  OF  THE  CONNECTIVE  TISSUES. 


329 


milk  in  a  glass.     It  is  found  in  the  cartilages  of  the  respiratory  appar- 
atus, of  the  nose,  of  the  ribs,  of  the  joints,  in  the  synchondroses,  and  in 

7i 


J 


Fig.  186. — Hyaline  cartilage,  x  240  d.  A,  surface  view  of  the  'procesnus  ensiforrius  of  the 
frog,  fresh  ;  k,  nucleus  ;  p,  protoplasm  of  cartilage  cell,  completely  filling  the  cavity  in 
the  cartilage  ;  ;/,  hyaline  matrix.  (Method  No.  48,  Appendix.)  B,  from  a  transverse 
section  of  the  cartilage  of  a  human  rib  examined  in  water  several  days  after  death.  The 
protoplasm  of  the  cartilage  cells  (z)  has  shrunk  from  the  wall  of  the  space  (A)  in  the 
cartilage.  The  nucleus  of  the  cartilage  cell  cannot  be  seen.  1,  two  cells  in  one  cartilage 
capsule  (k) ;  at  the  x  begins  the  development  of  a  partition  wall ;  2,  five  cartilage  cells 
embraced  within  a  capsule — the  lowest  cell  has  fallen  out,  so  that  we  perceive  the  empty 
cavity  in  the  cartilage  ;  3,  cartilage  capsule  cut  obliquely— on  this  account,  it  appears 
thicker  on  one  side  ;  U,  cartilage  caps\ile  not  cut  at  all — the  cartilage  cell  shines  through  ; 
ff,  hyaline  matrix  changed  in/,  into  rigid  fibres.     (Method  No.  49,  Appendix.) 

the  embryo  it  forms  the  cartilaginous  skeleton,  which  afterwards  is 
exchanged  for  bone.  It  is  characterized  by  its  homogeneous  matrix,  but 
the  matrix  may  undergo  peculiar  modifications.  Thus,  the  matrix  of 
cartilage  of  the  ribs  and  of  the  cartilages  of  the  larynx  are  changed,  by 
molecular  linear  arrangement,  into  rigid  fibres,  which  lend  to  the  cartil- 
age a  brilliancy  visible  to  the  naked  eye,  somewhat  resembling  that  of 
asbestos.  Fiu-ther,  there  are  found,  in  the  hyaline  matrix,  in  the 
cartilage  of  advanced  age,  deposits  of  lime  salts,  which  appear  at  the 
beginning  in  the  form  of  small  granules,  and  then  as  complete  capsules, 
situated  round  the  cartilage  cells.  The  cells  of  hyaline  cartilage  very 
frequently  show  forms  which  have  their  cause  in  the  processes  of 
growth.  Thus,  we  may  find  two  cells  in  one  cartilage  capsule  (Fig. 
186,  k).  These  have  been  developed  by  fission  of  the  cartilage  cell ;  in 
other  cases,  we  may  observe  between  two  such  cells  a  thin  jDartition 
wall  of  hyaline  substance  already  developed.  Further,  in  some  in- 
stances, a  partition  wall  is  not  immediately  formed.  The  two  cells  may 
divide  again  and  again,  and  thus  we  have  groups  of  four,  eight,  or 
more  cartilage  cells  surrounded  by  a  single  capsule  (Fig.  186,  2).  Such 
phenomena  have  justified  the  description  of  a  special  mode  of  cell  divi- 


330 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


sion,  the  so  called  endogenous  coll  di-\asion.     Cartilage  cells  of  adults  not 
infrequently  contain  small  drops  of  fat. 

(6)  Elastic  Cartilage  is  of  a  light  yelloAvish  colour.  It  is  found  in  the 
ear,  in  the  epiglottis,  in  the  cartilages  of  Wrisberg  and  of  Santorini, 
and  in  the  -processus  vocales  of  the  arytenoid  cartilages  of  the  larynx,  and 
in  the  Eustachian  tube.  It  shows  the  same  structure  as  hyaline  cartil- 
age, only  its  matrix  is  interpenetrated  ^vith  reticulations  of  elastic  fibres. 
The  elastic  fibres  are  not  produced  directl}-  out  of  the  cells,  but  by 


3. 


/'/ 


Fig.  187.— 1,  Elastic  cartilage,  x  240  d.  z,  cartilage  cell  (nucleus  not  visible) ;  Ic,  cartilage 
capsule.  1,  from  a  section  through  fhe  processus  vocalis  ol  the  arytenoid  cartilage  of  a 
woman  of  30  years.  Elastic  substance  is  in  the  forna  of  granules.  2  and  3,  from  a  sec- 
tion through  the  epiglottis  of  a  woman  of  (30.  (2)  More  delicate  reticulation.  (3)  Thicker 
reticulation.     (Method  No.  50,  Appendix.) 

means  of  a  metamorphosis  of  the  matrix,   and   they  appear  in    the 

environment  of  the  cartilage  cells  as  granules  (Fig.  187,  1),  and  at  a  later 

period  of  life  they  become  fibres. 

(c)  Connective  Tissue  or  White  Fihro-Cartilarje  is  found  in  the  ligamenta 

interverteh-alia,  or  intervertebral  discs,  in  the  uniting  substance  of  the 

pubic  and  sacro-iliac  symphyses,  the 
i,  ,  i  interarticular  plates  of  the  sterno- 
clavicular, temporo-maxillary,  knee, 
and  wrist  joints,  the  substance  serv- 
ing to  deepen  the  borders  of  the  aceta- 
bulum and  the  glenoid  cavity  of  the 
shoulder  joint,  the  tendinous  sheaths, 
and  the  sesamoid  bodies  occiu-ring  in 
some  of  the  tendons ;  but  some  of 
these,  which  are  more  fibrous  than 
cartilaginous,  are  covered  with  a 
thin  layer  of  true  cartilage.  The 
matrix  of  connective  tissue  car- 
tilage is  fibrillar  connective  tissue 
(Fig.  188,  g),  whose  loose  biuidles  run 
in  all  directions  and  form  an  irresiilar 


ff- 


I 


Fig.  188. — From  a  horizontal  section 
of  human  ligamenta  inteyt'ertebratia. 
X  240  d.  g,  connective  tissue  matrix  ; 
z,  cartilage  cell  (nucleus  indistinguish- 
able) ;  k,  cartilage  capsule  surrounded 
by  calcareous  gn^anules.  (Method  No. 
51,  Appendix.) 


STRUCTURE  OF  THE  CONNECTIVE  TISSUES.  331 

network.  The  few  thick-walled  cartilage  cells  existing  in  this  variety 
lie  in  small  groups  at  great  intervals.  In  the  centre  of  the  ligamenta 
intervertebralia,  there  is  found  a  soft  jelly-like  mass,  which  contains  large 
groups  of  cartilage  cells.  This  structure  is  the  remains  of  the  cJiorda 
dorsalis. 

All  cartilages,  with  the  exception  of  those  of  the  joints,  have  on  their 
outer  surface  a  fibrous  membrane,  the  perichondrium,  which  consists  of 
bundles  of  connective  tissue  running  in  different  directions,  mixed  with 
some  elastic  fibres.  At  the  place  where  cartilage  and  perichondrium 
come  into  contact,  the  one  kind  of  tissue  insensibly  merges  into  the 
other.  The  perichondrium,  therefore,  adheres  firmly  to  the  cartilage. 
The  perichondrium  is  supplied  mth  vessels.  The  vessels  in  growing 
cartilage  lie  in  canals  or  grooves.  In  the  adult,  cartilage  is  destitute  of 
vessels.  Nutrition  is  in  this  case  effected  through  diffusion  from  the 
outer  surface.  Whether  there  exist  proper  canal-like  j)assages,  re- 
sembling those  of  the  bones,  in  which  the  nourishing  fluid  circulates,  is 
still  doubtful,  in  spite  of  various  contentions  to  the  contrary. 

Cartilage  contains  from  54  to  70  per  cent,  of  water,  a  substance  termed 
chondrogen  (p.  79),  which  yields  chondrin  on  prolonged  boiling,  a  small 
quantity  of  fat  (from  2  to  5  per  cent.),  and  a  variable  amount  of  salts. 
The  salts  consist  of  phosphates  of  lime  and  of  magnesia,  chloride  of 
sodium,  carbonate  of  soda,  and  sulphates  of  soda  and  potash.  The 
amount  of  salts  has  been  found  to  vary  from  2  to  as  much  as  7*29  per 
cent.  As  life  advances,  the  percentage  of  salts  in  cartilage  increases. 
It  is  to  be  noted  that  cartilage  contains  only  a  very  small  proportion  of 
salts  of  potash.  By  prolonged  boiling,  white  fibro-cartilage  yields 
gelatin,  and  yellow  fibro-cartilage,  elastin. 

Cartilage  is  originally  developed  from  a  cellular  blastema.  In  the 
first  stage,  the  cells  are  set  close  together  in  a  soft  substance,  which 
exists  in  small  quantity.  Subsequently,  this  substance  increases  in 
amount  between  the  cells,  and  by  its  increase  and  encroachment  upon 
the  cells,  it  separates  them  to  a  greater  and  greater  distance  from  each 
other.  The  farther  growth  of  cartilage  takes  place,  in  part  by  the 
multiplication  of  the  cells  by  fission,  and  in  part  by  the  formation  of 
matrix  around  and  between  the  cells.  As  above  explained,  changes  in 
the  structure  of  the  matrix  lead  to  the  formation  of  the  diff"erent 
varieties  of  cartilage. 


332 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


3.   Bone. 

If  Ave  saw  through  a  fresh  tubular  bone,  we  immediately  perceive 
that  its  structure  is  not  everywhere  the  same.  The  part  near  the 
periphery  or  surfixce  is  composed  of  a  rigid,  hard  substance  termed 
substantia  comjxida.  There  exist,  round  the  medullary  cavity  of 
the  bone,  small  and  delicate  lamince  or  traheculce,  which,  running  in  all 
directions,  form  an  irregular  reticulated  structure.  This  honeycomb- 
like substance  is  termed  substantia  spongiosa.  The  meshes  of  the  substantia 
spongiosa  and  the  central  cavity  are  filled  AWth  a  soft  matter  termed  the 
marroiv.  The  svurface  of  bone  is  covered  with  a  fibrous  membrane  termed 
the  periosteum.  The  relation  between  compact  and  spongy  sul  jstance  is 
somewhat  different  in  short  bones,  inasmuch  as  these  consist  chiefly  of 
spongy  substance,  and  the  compact  substance  is  confined  solely  to  a 
narrow  zone  on  the  surface.  Flat  bones  have  sometimes  thicker,  some- 
times thinner,  layers  of  compact  substance,  whilst  the  internal  portion 
of  a  fiat  bone  is  filled  A\dth  spongy  substance.  The  structure  of  the 
epiphyses  of  tubular  bones  resembles  that  of  short  bones ;  they  consist 
chiefly  of  spongy  substance. 


The  Mickoscopical  Structure  of  Bone. 

1.  The  substantia  spongiosa  is  built  up  of  small  lamince  of  bone,  which 
consist  of  a  matrix  perforated  by  a  network  of  canals.  The  matrix  is 
formed  of  organic  and  inorganic  parts,  so  that  a  high  degree  of  hard- 
ness, rigidity,  and  elasticity  is  attained.  It  is  homogeneous  or  slightly 
striated,  and  it  contains  nimierous  hollow  spaces,  from  15  to  27  /a  long, 
termed  lacunce  (Fig.  190,  h),  which  are  united  by  numerous  processes,  the 
A 


Fig.  1S9.— From  a  dry  strip  of 
the  bone  of  an  adiilt  man, 
X  5(30  d.  h,  lacunas ;  A,  seen 
from  the  surface  ;  B,  from  the 
side ;  Ic,  canaliculi  of  bone  ;  g, 
matrix  of  bone.  (Method  Xo. 
52,  Appendix.) 


Fig.  100.— From  a  section,  a,  of  the  humerus 
of  a  human  embryo  of  four  months.  6,  of 
bone  of  an  adult,  X  500  d.  Bone  corpuscles, 
z,  lying,  k,  in  the  lacunse;  the  canaliculi 
are  visible  in  some  places  ;  g,  matrix. 
(Method  Xo.  53,  Appendix.) 


bone  canals  or  canaliculi.  These  canals  not  only  communicate  Avith  each 
other,  but  also  open  freely  on  the  surface  of  the  small  laminje 
of  the  bone. 


STRUCTURE  OF  THE  CONNECTIVE  TISSUES.  333 

In  this  manner,  a  system  of  small  canals  penetrates  the  entire  matrix. 
In  the  lacunae  there  lie  nucleated  cells  of  an  oval  form.  Whether  the 
processes  of  the  cells  passing  into  the  canaliculi  anastomose  is  still 
doubtful.  The  small  laminse  of  the  substantia  spongiosa  contain  no 
vessels. 

2.  The  substantia  compada  is  built  up  in  a  somewhat  more  complex 
manner.  It  contains,  in  addition  to  the  above-mentioned  system  of 
narrow  canals,  a  system  of  much  coarser  canals,  22  to  110  /x  broad, 
which  divide  dichotomously  and  form  a  mde-meshed  net-work.  These 
coarser  canals  contain  blood-vessels,  and  they  are  termed  Haversian 
canals.  The  direction  of  their  course  in  the  long  bones,  in  the  ribs, 
in  the  clavicle,  and  in  the  inferior  maxilla,  is  parallel  to  the  long  axis 
of  the  bone.  In  the  short  bones,  as,  for  instance,  the  vertebrae,  the 
direction  is  mainly  perpendicular.  In  flat  bones,  on  the  other  hand, 
the  Haversian  canals  run  parallel  to  the  surface  of  the  bones,  not 
infrequently  in  radiated  lines  streaming  from  one  point.  An  example 
of  this  arrangement  is  seen  in  the  parietal  bones.  The  Haversian 
canals  open  on  the  outer  (Fig.  191,  x ),  as  well  as  on  the  inner 
(Fig.  191,  X  X  )  surface,  and  they  are  directed  towards  the  substantia 
spongiosa.  The  matrix  of  the  compact  substance  is  stratified  into  lamellae. 
Three  systems  of  lamellse  (Fig.  192)  may  be  distinguished :  (1)  A  system  of 
lamellae  forming  a  ring  round  the  Haversian  canals.  AVhen  these  are 
cut  transversely,  they  appear  like  a  number  (8  to  15)  of  rings  placed 
concentrically  round  the  Haversian  canal.  Such  concentric  lamellse  are 
called  the  Haversian  or  special  lamellce.  (2)  The  intersections  of  the  Haver- 
sian systems  of  lamellae  impinge  partially  on  each  other,  but  they  are 
also  partially  separated  by  layers  of  the  bone,  which  are  stratified 
in  another  direction.  We  term  these  lamellae  which  run  more  irregu- 
larly between  the  Haversian  systems  of  lamellae,  the  interstitial  or 
intercalary  lamellce.  (3)  These  are  united  by  a  third  system  of  lamellae 
which  run  parallel  with  the  outer  surface  of  the  bone,  and  these  are 
termed  the  external  systems  of  lamellce.  Lamellae  are  also  sometimes 
found  on  the  inner  surface ;  and  such  are  termed  internal  lamellce.  The 
lacunae  have  definite  positions  in  the  substantia  compacta.  In  the 
Haversian  lamellar  systems,  they  are  placed  ■with  their  longitudinal  axis 
parallel  to  the  longitudinal  axis  of  the  Haversian  canals,  and  bent 
towards  the  surface,  so  that  in  transverse  sections  they  appear 
concentrically  curved  to  the  transverse  section  of  the  Haversian  canal 
(Fig.  192).  In  the  interstitial  lamellae  the  lacunae  are  irregular,  but 
in  the  external  lamellae  they  run  "^"ith  their  surfaces  parallel  to  the 
sui'faces  of  the  lamellae. 

3.  The  marroiv  of  the  hones  exists  in  the  axial  ca^aties  of  the  long 


334 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


bones,  occupies  the  meshes  of  the  spongy  substance,  and  also  occurs 
in  the  larger  Haversian  canals.     As  it  is  either  of  a  red  or  yellow  colour, 


Haversian  canals. 


Matrix. 


Periosteum. 


Drops  of  fat. 


Fio.  191. — Portion  of  a  longitvidinal  section  through  a  metacarpal 
bone  of  a  man,  x  30  d.  In  the  preparation  drops  of  fat  are  seen  in 
the  Haversian  canals.  At  x,  x,  x,  the  Haversian  canals  open  on  to 
the' surface.     (Method  No.  54,  Appendix.) 

we  distinguish  red  from  yelloiv  marrow.  The  yellow  marrow  is  richer 
in  fat  than  red  marrow ;  other^\ase  the  elements  in  both  varieties  are 
identical.  The  red  marrow  is  found  in  the  spongy  substance  of  short 
and  flat  bones,  in  the  epiphyses  of  the  long  bones,  and  in  the  central 
<;avity  of  long  bones  of  small  animals.  The  3^  ellow  marrow  fills  up  the 
medullary  cavity  of  the  long  bones. 

In  old  and  sick  persons  the  marrow  may  be  of  a  mucous  character, 
and  reddish-j^ellow.  It  is  then  termed  gelatinous  bone  marrow,  and  it 
owes  its  character  simply  to  the  small  amount  of  fat  in  it. 

The  elements  of  marrow  are  (1)  a  small  amount  of  fibrillar  connective 
tissue ;  (2)  fttt  cells  ;  (3)  leucocytes  (which  are  here  termed  bone  marrow 
cells) ;  and  (4)  giant  cells  {myeloplaxes).  The  latter  are  large  cells  of 
very  irregular  shape  consisting  of  protoplasm  and  of  one  or  more  nuclei. 
There  are  giant  cells  with  clear  nuclei  and  giant  cells  with  nuclei  glitter- 
ing and  intensely  brilliant  in  colour.  The  shape  of  the  nuclei  is  very 
various,  round,  irregular,  ribbon-shaped,  or  ring-shaped  (Fig.  193,  2  r)  or 
it  may  show  a  network  (Fig.  75,  p.  210).  Out  of  giant  cells  containing 
one  nucleus,  cells  containing  many  nuclei  may  be  developed  hy  means  of 


STRUCTURE  OF  THE  CONNECTIVE  TISSUES. 


835 


the  fission  of  the  single  nucleus  (Fig.  193,  3  r),  or  along  with  a  correspond- 
ing fission  of  part  of  the  protoplasm.     If  both  nucleus  and  protoplasm 


Periosteum. 
External  lamellaj. 
Haversian  canals. 

7^  Haversian  lamelte. 


Interstitial  lamella}. 
Internal  lamellse. 


Marrow. 


Fig.  192. — Portion  of  a  transverse  section  of  a  metacarpal  bone  of  a  man, 
X  50  d.  In  the  Haversian  canals  there  is  still  some  marrow  (fat  cells). 
h,  Haversian  spaces.     (Method  No.  55,  Appendix.) 

divide,  cells  with  one  nucleus  are  produced.  It  has  also  been  supposed 
that  in  the  formation  of  giant  cells  containing  many  nuclei,  there  may 
have  been  the  coalescence  of  several  cells  of  simpler  construction. 
Finally,  in  red  marrow,  we  may  find  (5)  cells  containing  a  nucleus, 
with  yellow-coloured  protoplasm,  resembling  red  blood  corpuscles.  They 
are  regarded  as  mother  cells  (licematoUasts)  of  the  red  blood  corpuscles. 


O 


1  Z  3 

Fig.  193. — Elements  of  bone  marrow  freshly  isolated  from  the  vertebra; 
of  a  calf,  X  560  d.  1,  in  a  solution  of  common  salt ;  i',  coloured  with 
picrocarmine ;  3,  after  the  addition  of  acidulated  glycerine,  k,  mar- 
row cells;  k',  two  bone  marrow  cells,  containing  deposits  of  pig- 
ment granules — the  right  seen  on  the  side,  the  left  on  the  surface ; 
b,  coloured  blood  corpuscles  (without  nucleus)  ;  r,  giant  cells.  The 
right  shows  sideways  two  nuclei  in  process  of  fission  and  one  exactly 
similar  on  the  surface  x.     (Method  No.  56,  Appendix.) 

Yellowish  pigment  granules  occurring  in  different  cells  are  regarded 
as  the  remains  of  red  blood  corpuscles  that  have  undergone  disintegra- 
tion, 

4.  The  Periosteum  is  a  membrane  consisting  of  strong  connective 


336  THE  PHYSIOLOGY  OF  THE  TISSUES. 

tissue  fibres.  "We  can  distinguish  two  hiyers.  The  outer  hxyer  is 
characterized  by  its  richness  in  blood-vessels,  and  it  is  intimately  con- 
nected Avith  neighbouring  structures,  such  as  tendons,  fascia,  etc.;  the 
inner  layer  is  poor  in  blood-vessels,  but,  on  the  other  hand,  it  is  very 
rich  in  elastic  fibres.  On  its  inner  surface,  we  find  a  layer  of  punctated 
cubical  cells  which  are  of  importance  in  the  development  of  the  bone. 
The  periosteum  is  united  sometimes  more  firmly,  sometimes  more 
loosely  to  the  bone,  the  connection  being  established  by  the  blood- 
vessels and  by  peculiar  bundles  of  connective  tissue  penetrating  into 
the  external  lamella3.  These  bundles  are  termed  the  fibres  of  Sharpey. 
A        -■■■-      - 


Fig.  194. — Portions  of  transverse  sections  of  huiacrus  of  a  new-born  child,  x  240  d. 
A',  Sharpey's  fibres.  A,  From  a  teazed  preparation,  seen,  B,  lengtliways ;  C,  transversely. 
Ic.  canaliculi  of  bone.     (Method  No.  5",  Appendix.) 

5.  The  hlood-vessels  of  the  bone,  of  the  marrow,  and  of  the  periosteum, 
are  closely  related.  From  numerous  veins  and  arteries  of  the  perios- 
teum, small  branches,  not  capillaries,  enter  into  the  Haversian  canals, 
and  the  vessels  in  the  canals  may  unite  on  the  inner  surface  of  the 
medullary  cavity  with  the  vessels  of  the  marrow.  The  latter  receive 
blood  by  means  of  the  arterise  nutritise,  or  nutrient  arteries,  which 
branch  off  through  the  substantia  compacta.  The  vessels  in  the  marrow 
unite  to  form  a  rich  network  of  blood-vessels.  The  veins  issuing. 
out  of  the  capillaries  of  the  marrow  have  no  valves.  It  is  very  pro- 
bable that  the  blood-vessels  ^Aithin  the  marrow  of  the  bones  may,  in 
some  places,  have  no  definite  walls. 

6.  The  nerves  are  situated  partly  in  the  periosteum,  where  they 
sometimes  terminate  in  Vater's  ctyrpusdes  (a  form  of  touch  corjDuscle),  and 
they  may  be  found  in  the  Haversian  canals  and  in  the  marrow.  They 
are  both  meduUated  and  non-medullated. 

Development  of  Boxes  or  Ossification. 

The  bones  are  formations  appearing  late  in  development.  There  is  a 
time  in  embryonic  life  in  Avhich  muscles,  nerves,  vessels,  brain,  and  the 


STRUCTURE  OF  THE  CONNECTIVE  TISSUES.  337 

spinal  marrow  are  already  well  formed,  but  there  is  yet  not  a  trace  of 
bone.  The  skeleton  of  the  body  is  at  that  time  formed  of  hyaline 
cartilage.  With  the  exception  of  some  portions  of  the  skull  and  of  the 
face,  all  the  osseous  parts  of  the  skeleton  are  first  represented  by 
cartilage.  We  thus  find,  for  example,  in  the  upper  extremities,  the 
humerus,  radius,  ulna,  carpus,  and  the  parts  of  the  skeleton  of  the 
hand  composed  of  portions  of  cartilage,  which,  unlike  the  bones 
appearing  later,  are  not  hollow,  but  solid  throughout.  Gradually  the 
bony  skeleton  comes  to  occupy  the  place  of  the  cartilaginous  skeleton. 
All  the  bones  which  were,  in  the  embryonic  period,  formed  by  means  of 
cartilage,  are  called  cartilaginous  or  primary  bones.  The  other  bones, 
which  have  no  cartilaginous  predecessors,  are  termed  secondary  or  con- 
nective tissue  bones. 

To  the  primary  bones  belong  all  the  bones  of  the  trunk,  of  the 
extremities,  the  greater  portion  of  the  base  of  the  skull,  the  occipital 
bone,  with  the  exception  of  the  upper  flat  portion  of  it,  the  sphenoid 
bone,  the  petrous  portion  of  the  temporal  bone,  the  small  bones  of  the 
ear,  the  ethmoid  bone,  and  the  vomer. 

To  the  secondary  bones  belong  the  bones  forming  the  lateral  parts  of 
the  skull,  the  roof  of  the  skull,  and  almost  all  the  bones  of  the  face. 

A. — Developmej^t  of  the  Primary  Bones. 

Two  processes  are  to  be  observed  here — (1)  The  formation  of  bone 
substance  m  cartilage  already  existing,  termed  enchondrial  or  endo- 
chondrial  ossification,  and  (2)  the  formation  of  bone  in  the  immediate 
neighbourhood — that  is  to  say,  on  cartilage.  The  latter  process  is 
termed  periosteal,  or  better  perichondrial  ossification.  Both  begin  almost 
simultaneously,  the  perichondrial  often  somewhat  earlier  than  the 
other. 

1.  Enchondrial  Ossification. — The  first  changes  consist  in  the  cells 
enlarging  in  a  definite  part  of  the  cartilage.  They  then  divide  in 
such  a  way  that  several  cells  lie  in  one  cavity  of  the  cartilage.  The 
matrix  becomes  finely  granular  and  dim  by  the  deposition  of  calcareous 
(or  earthy)  salts  (Fig.  195,  V).  Such  places  where  the  cartilage  is  thus 
changed  can  soon  be  observed  by  the  naked  eye,  and  they  are  termed 
centres  of  ossification,  or  better,  centres  of  calcification.  The  portions  of  the 
cartilage  more  remote  from  a  centre  of  calcification  increase  in  thickness 
and  length,  while  at  the  centre  of  calcification  no  further  growth  of  cells 
takes  place.  A  portion  of  the  bony  skeleton  is  developed  at  that  spot 
(Fig.  195).  Meanwhile  there  has  appeared  on  the  upper  surface  of  the 
centres  of  calcification  a  tissue  termed  osteogenous  tissue,  rich  in  young 


338 


THE  PIIYSIOLOHY  OF  THE  TISSUES. 


cells  and  vessels.  This  jDcnetrates  into  the  cartilage,  and  causes  the 
calcified  matrix  to  break  doAvn.  The  cartilage  cells  become  free  and 
mingle  w-ith  the  cells  of  the  osteogenic  tissue,  and  thus  a  small  cavity 

.  ..(/>r^faSis:*jiivti.„_ 


Fig.  195. — From  a  C'orsoplantar  longitudinal 
section  of  the  great  toe  of  a  human  embryo 
of  four  months.  Two  thirds  of  the  first 
phalanx  are  indicated,  x  50  d.  r,  centre  of 
ossification  ;  li,  cavities  of  the  cartilage  en- 
larged, containing  several  cartilage  cells.  The 
cells  cannot  be  recognized  here  under  a  feeble 
magnifying  power,  but  only  their  point- 
shaped  nuclei,  g,  calcified  matrix  of  cartil- 
age ;  K,  hyaline  cartilage  ;  k,  growing 
cartilage,  we  perceive  the  cartilage  cells 
arranged  in  groups  of  three  to  four  cells  ;  each 
group  is  produced  by  the  repeated  division  of 
one  cartilage  cell ;  o,  osteogenous,  or  bone 
forming  tissue;  P,  perichondria!  bone. 
(Method  No  58,  Appendix.) 


Fig.  196. — Fi-om  a  dorsopalmar  longi- 
tudinal section  of  a  finger  of  a  four 
months'  human  embryo.  Two  thirds 
of  the  second  phalanx  are  shown, 
X  50  d.  il/,  primordial  medullary 
space  containing,  h,  cartilaginous  mar- 
row and  blood-vessels ;  7i,  enlarged 
cartilage  cavities  ;  </,  calcified  matrix 
of  cartilage,  in  the  form  of  indented 
processes,  g' ,  projecting  into  the  medul- 
lary space  ;  0,  osteogenous  tissue;  P, 
perichoiidrial  bone ;  £,  enchondrial 
bone  is  formed  only  in  the  form  of  fine 
leaflets.  (See  under  higher  power  in 
Fig.  197.)    (Method  No.  59,  Appendix.) 


is  formed  at  the  centre  of  calcification.      This  cavity  is  termed  the 
immordial  meduUary  space. 

The  jDortion  of  cartilage  next  the  centre  of  calcification  undergoes 
changes  similar  to  those  above  described — that  is  to  say,  there  are 
changes  in  the  matrix  and  in  the  cartilage  cells.  There  is  gradually  an 
ever-advancing  increase  of  the  medullary  space,  while  new  parts  of  the 
cartilage  melt  down.  Entire  groups  of  cartilage  cells  thereby  become 
exposed,  while  the  calcified  cartilage  substance,  situated  between  these, 
is  still  preserved  in  the  form  of  indented  processes,  projecting  into  the 
medullary  space  (Fig.  196,  g).  The  medullary  space  is  now  a  cavity 
communicating  with  many  surrounding  diverticula  or  pouches,  and  all 
are  filled  with  blood-vessels  and  cells,  termed  the  cartilage  marrow  cells. 


STRUCTURE  OF  THE  CONNECTIVE  TISSUES. 


339 


F 


'7 


c 


Ob' 


M 


These  cells  play  an  important  part  in  bone  develoj^ment.     They  either 
become  the  marrow  cells  of  bone,  preserving  their  form,  or  they  become 
fat  cells,  or — and  this  the  most  important — they  become  bone-forming 
cells  or  osteoblasts.    Osteoblasts 
are  cells  which  are  deposited 
after  the  manner  of  unstrati- 
fied  epithelium  on  the  walls 
of  medullary  spaces,  and  there 
they   develop  the   matrix   of 
bone  (Fig.  197). 

At  the  beginning,  all  osteo- 
blasts rest  on  the  matrix  of 
the  bone ;  but  at  a  later  date 
they  come  to  be  embedded  in 
the  matrix  itself,  and  they 
thus  become  hone  (wpusdes  or 
hone  cells,  lying  in  the  lacunae 
(Fig.  190,  p.  332).  The  medul- 
lary space  is  now  lined  by 
the  activity  of  the  osteo- 
blasts, with  a  thin  layer  of 
bone,  which  gradually  be- 
comes thicker,  and  the  in- 
dented laminae  of  calcified 
cartilage  (Fig.  197,  g),  are  quickly  surrounded  with  circular  layers  of 
young  bone  (Fig.  197,  E).  Thus,  the  earlier  solid  jDortion  of  cartilage 
is  by  degrees  converted  into  spongy  bones,  whose  pouches  or  irregiilarly- 
formed  honeycomb-like  meshes  still  contain  the  remains  of  calcified 
matrix  (Fig.  197,  E,  g). 

2.  Perichondrial  Ossification. — This  mode  of  ossification  is  effected  also 
by  means  of  osteoblasts,  which  form  osteogenic  tissue  on  the  outer 
surface  of  the  centres  of  calcification  (Fig.  196,  0).  By  the  activity  of 
■osteoblasts,  strata  of  bone  substance  are  also  formed  on  the  outer  sur- 
face of  the  cartilage  (Fig.  195,  F),  but  the  masses  of  bone  thus  formed 
from  perichondrium  are  distinguished  from  those  formed  in  cartilage  in 
having  no  remains  of  calcified  matrix  of  cartilage,  the  formation  of  bone 
in  perichondrium  being  efibcted  only  on  the  circumference  of  bones,  not 
in  the  interior  of  cartilage.  The  perichondrial  layer  of  the  bones  does 
not  consist  of  a  stratum  of  uniform  thickness,  but  in  many  places  it  is 
very  much  thicker  than  at  others  (Fig.  198,  h,  h).  Depressions  are  also 
formed,  in  which  blood-vessels  lie  surrounded  by  osteoblasts.  At  the 
beginning,  the  grooves  or  depressions  are  only  channels  open  towards 


Fig.  197. — From  a  longitudinal  section  of  the  first 
phalanx  of  the  finger  of  a  human  embryo  of  four 
months,  x  240  d.  31,  inlets  or  recesses  of  the  pri- 
mordial medullary  space,  filled  with  cartilage  cells, 
and  h,  blood-vessels  ;  /•,  giant  cell  ;  rj,  calcified 
matrix  ;  S,  young  enchondrial  bone  substance  seen 
from  the  side ;  E',  seen  on  the  broad  surface.  Here 
we  already  perceive  indented  bone  cavities  with 
bone  cells.  Ob,  Osteoblasts  still  irregularly  scattered 
about. ;  P,  perichondrial  bone  ;  0>j',  osteoblasts  by 
this  time  arranged  in  a  layer ;  the  two  uppermost 
osteoblasts  x  are  already  surrounded  to  the  extent  of 
onehalf  with  bone  matrix.  -F,  jjeriosteum.  (Method 
No.  CO,  Appendix.) 


340 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


the  peripheiy ;  but  with  the  gradually  increasing  thickening  of  the 
perichondrial  strata  of  bone  the  channels  are  closed  up  (/t'),  so  as  now 
to  become  canals  containing  vessels.  These  are  the  Haversian  canals. 
By  the  activity  of  the  osteoblasts  enclosed  in  the  Haversian  canals,  new 
bone  strata,  termed  the  later  Haversian  lamellae,  are  formed. 


b    h 


oIk 


-^-^on\:\ 


Fig.  19S.— Portion  of  a  transverse  section  through  the  diaphysis  of 
the  humerus  of  a  human  embryo  of  four  months,  x  SO  d.  P, 
periosteal  trabeculaj  having  osteoblasts,  ob,  on  their  margins  ;  h,  h,  h, 
small  Haversian  canals  shut  in  by  bone  formation  ;  h',  small  Haver- 
sian canal  closed  ;  E,  encbondrial  trabeculfe  of  bone  likewise 
covered  with  osteoblasts  and  containingr  the  remains  of  calcified  carti- 
lage matrix,  g ;  z,  marrow  cells;  h,  blood  vessels.  (Method  Xo.  61, 
Appendix.) 

Thus   a   bone   has   been  formed    out    of  a    cartilage    by   the    dis- 
solution and  removal  of  the  cartilage  and  the  supplying  of  its  place 

by    bone   (encJiondrial   ossification)   and   by 
vY/^  — ^    -      <yr  the  deposition  of  new  masses  of  bone  on 

fi  ~        -  ';'^'_--'Al::flV^  jg3^  the  outside  {perichondrial  ossification).     The 

:  ;'  essence     of     the     processes     above     de- 

scribed     consists     in     a     dissolution     of 
the   original   cartilaginous   portion   of  the 
skeleton  and  in  a  rebuilding  of  it  by  the 
^       „,    ^  ,.      development  of  bone  substance.     AVe  term 

Fig.  199. — From  a  transverse  section  _  '■ 

of  the  lower  jaw  of  a  newly-born  dog,   this  mode  of  bouc  formation  the  neoplastic 

X  240  d..  Metaplastic  type.     C,  matrix  _  ,  ... 

ofcartiiagebecoming,A^,bonematris,   type  of  ossification  as  distinguished  from  a 

directly ;  Cz,  cartilage  cells ;  Kz,  bone  .  , 

cells;  CK,  transition  from  cartilage  mode  Seldom  occumns;  (as,  for  example,  in 

cells  to  bone  cells.      (Method  Is  o.  62,  .  o     ^  \  n     i      \ 

Appendix.)  the  ossification  01  the  angle  of  the  lower 

jaw)  in  which  the  cartilage  is  not  destroyed  but  is  simply  turned  into 
bone,  the  matrix  of  the  cartilage  becoming  the  matrix  of  the  bone  and 
the  cartilau'e  cells  becoming;  bone  cells.  This  mode  is  termed  the  metor- 
plastic  type  of  ossification  (Fig.  199). 


STRUCTURE  OF  THE  CONNECTIVE  TISSUES. 


341 


B. — Development  of  the  Secondary  Bones. 
In  this  case,  the  basis  on  which  ossification  is  effected  is  not  cartilage 


but  connective  tissue.  Indivi- 
dual connective  tissue  fibres 
become  calcified ;  on  these,  osteo- 
blasts (Fig.  200),  proceeding  from 
•embryonic  cells,  are  deposited; 
bone  is  then  formed  in  the  man- 
ner above  described. 


S 


■,^-y^^: 


a? 


Fig.  200. — From  a  surface  section  of  the  bone  on  the 
crown  of  the  head  of  a  human  embryo,  x  240  d. 
T       ,1  T  1  •    ,-  5,  bundles  of  connective  tissue  calcified  at  B-,;  oh. 

In    the    precedmg    descriptions    osteoblasts.     (Method  Xo.  63,  Appendix.) 

we  have  noticed  only  the  processes  occurring  in  the  first  development 
of  a  bone.  The  further  growth  of  a  bone,  as,  for  example,  the  growth 
of  the  tubular  bones,  now  takes  place  in  such  a  manner  that  longitudinal 
growth  is  carried  on  by  extension  of  the  primordial  marroAv  space  and 
enchondrial  ossification  on  the  basis  of  the  evergrowing  cartilage.  The 
growth  in  thickness  is  carried  on  by  the  deposition  of  new  strata  of  bone 
by  the  periosteum. 

Flat  bones  formed  in  connective  tissue  grow  by  means  of  the  forma- 
tion of  new  masses  or  layers  of  bone  on  the  margins  (superficial 
growth),  and  on  the  flat  surfaces  (growth  in  thickness).  The  growth 
of  all  bones  is,  however,  probably  effected  not  only  by  means  of  the 
deposition  of  new  strata  of  bone  or  appositional  growth,  but  also  by 
means  of  the  expansion  of  the  bone  substance  already  formed  or  by 
interstitial  gro"\vth.  It  must  also  be  noticed,  in  the  last  place,  that  the 
bone  substance,  after  it  has  once  been  formed,  does  not  remain  in  a  com- 
pleted state,  but  very  soon  again  passes  through  a  process  of  dissolu- 
tion. This  dissolution  occurs  not  only 
in  the  formation  of  the  cavities  of  the 
tubular  bones  and  in  the  typical  surfaces 
of  absorption,  but  also  in  such  places  as 
those  on  which  new  bone  substance  is 
once  more  formed  at  a  subsequent 
period. 

Wherever  reabsorption   of  bone  sub- 
stance  occurs,  we  find  giant  cells  placed    Fig.   201.— Prom  a  transverse  section  of 
„  ,  .  PIT  t^6  humerus  of  a  newly-born  kitten,  x 

m  lOSSSe  or  depressions  01  the  bone  240  d.  Small  Haversian  canal,  ^,  contaln- 
,  ^       TT        7  •    )       7  rm  •       ,     ii^g  t^^'o  vessels  and  marrow  cells ;  K,  bone ; 

termed    Howsmps    lacunce.      Ihe   giant   x,  HowsMps  lacunaj,  in  which,  ij,  giant 

n  ,  1       J       7     J  cells   (osteoclasts)  lie;   X„  empty  lacuna. 

<;ells  are  termed  osteoclasts.  (Method  xo.  64,  Appendix.) 


HZ 


342  TIfK  PHYSIOLOGY  OF  THE  TISSUES. 


Chemical  Composition  of  Bonk. 

We  may  determine  the  chemical  composition  of  a  bone  cither  l)y 
burning  the  bone  and  analyzing  the  ash,  or  by  macerating  the  bone  in 
dilute  acids,  by  which  the  earthy  matters  are  dissolved,  leaving  the 
organic  basis.  The  latter  consists  of  a  substance  named  collagen,  which 
yields  gelatin  on  boiling.  Even  dry  bones  yield  from  30  to  40  per  cent, 
of  gelatin.  The  salts  contained  in  bone  consist  chiefly  of  the  tri-basic 
phosphate  of  lime,  phosphate  of  magnesia,  carbonate  of  lime,  chlorides 
of  sodium  and  of  potassium,  and  fluoride  of  calcium.  Analysis  also  yields, 
a  small  quantity  of  albumin,  fat,  and  alkaline  sulphates,  which  are  pro- 
bably derived  from  the  blood-vessels  and  nerves  of  bone.  It  is  probable 
that  the  earthy  matter  is  simply  infiltrated  into  the  organic  substance 
of  bone,  and  that  it  is  not  in  a  state  of  actual  chemical  combination 
with  it. 

The  compact  tissue  of  bone  contains  from  3  to  7  per  cent,  of  water,  while  the 
amount  in  spongy  tissue  may  vary  from  12  to  30  per  cent.  The  amount  of  earthy 
matter,  as  determined  by  the  quantity  of  ash,  varies  considerably,  as  shown  by  the 
fact  that  Rees  obtained  the  following  results — Earthy  matter  from  temporal  bone? 
63'5  per  cent.  ;  from  scapula,  54'51  per  cent. ;  from  the  bones  of  a  foetus  of  seven 
months,  59  "62  per  cent. ;  of  an  infant  of  nine  months,  56  "43  per  cent. ;  of  a  child 
of  five  years  of  age,  67 '8  per  cent, ;  of  a  man  of  twenty-five  years  of  age,  68  "97  per 
cent.  ;  of  a  woman  of  sixty-two  years  of  age,  69'82  per  cent.;  and  of  a  W'oman  of 
seventy-two  years  of  age,  66"81  per  cent. 

The  following  analyses  of  bone  show  its  composition  in  1000  })arts^ 

Femur  of  man  Femtr. 

aged  30  years. 


Compact  Spongy 

tissue.  tissue. 

Organic  matter,    - SIO'S                314-7  358  2 

Mineral  matter, 689-7                685-3  64rS 


1000-0  1000-0  1000-0 


The  mineral  matter  consisted  of— 
Phosphate  of  lime,     ^ 
Fluoride  of  calcium,  J  " 

Carbonate  of  lune, 73-3 

Phosphate  of  magnesia,       -     -     -       13-2 
Chloride  of  sodium,  etc.,     -     -     -         6-9 

689-7  685-3  641-8 

The  organic  matter  consisted  of — 
Fat,    ----------       13-31 

Collagen, -     -     -     297-0/ 


83-5 

193-7 

10-3 

10-0 

9-2 

9-9 

314-7  358-2 

310-3  314-7  358-2 


STRUCTURE  OF  THE  CONNECTIVE  TISSUES.  343 

The  long  bones  of  the  skeleton  are  somewhat  richer  in  mineral  matter 
than  the  others.  Phosphate  of  lime,  as  the  above  analysis  shows, 
exists  in  larger  amount  in  compact  than  in  spongy  bone.  The  bones  of 
herbivora  are  richer  in  carbonate  of  lime  than  those  of  carnivora.  Salts 
become  more  abundant  as  age  advances,  so  that  the  bones  become  more 
brittle.  It  has  been  found  possible,  by  giving  to  an  animal,  food  con- 
taining salts  of  alumina  or  strontia,  to  replace  part  of  the  lime  in  bone 
by  one  or  other  of  these  substances,  without  altering  the  structure  and 
general  properties  of  bone. 

Chap.  XII.— THE  PHYSICAL  AND  VITAL  PROPERTIES  OF  THE 
CONNECTIVE  TISSUES. 

I.  Physical  Properties. 

1.  Specific  Weight  or  Density. — -This  varies  within  wide  limits,  of  which 
the  extremes  are  afforded  by  adipose  tissue  and  bone.  The  lightness 
of  adipose  tissue,  which  is  largely  employed  in  the  body  as  a  protective 
substance  for  delicate  organs,  is  of  importance,  as  it  diminishes  the  total 
weight  of  the  body,  and,  consequently,  the  muscular  force  required  to 
move  it. 

2.  Consistence. — This  varies  from  a  diflfluent  or  semifluid  state  as  in 
jelly-like  matter  of  the  umbilical  cord,  to  considerable  hardness  as  in  bone. 
The  consistence  depends  upon  the  amount  of  water  contained  in  the 
substance.  Thus,  the  jelly-like  tissue  contains  about  ninety-eight,  and 
bone  about  three  per  cent.,  of  water. 

3.  Cohesion. — This  depends  upon  the  adhesion  of  the  molecules  form- 
ing the  tissue,  or  the  union  side  by  side  of  the  fibres  composing  it. 
The  amount  and  direction  of  the  cohesion  may  be  indicated  by  the  man- 
ner in  which  the  tissue  yields  to  force.  Thus,  costal  cartilage  will  break 
more  easily  in  the  transverse  than  in  the  longitudinal  direction,  while  in 
such  structures  as  tendon,  it  is  more  easy  to  separate  the  fibres  from 
each  other  than  to  tear  them  across.  The  forces  which  act  upon  con- 
nective tissues,  and  which  are  resisted  by  their  cohesion,  are  traction 
or  pulling,  pressure,  flexion,  and  torsion.  The  amount  of  cohesion 
may  be  determined  by  ascertaining  the  weight  that  will  cause  rupture. 
Thus,  if  we  take  the  unit  of  square  surface  as  a  square  millimetre,  the 
weight  in  kilogrammes  required  to  cause  a  rupture  of  the  tissue  has  been 
found  to  be  as  follows — Bone,  7*7;  tendon,  6*9;  arteries,  0"16;  veins, 
0*12.  Bone  and  tendon  present  great  resistance  to  traction.  Thus  the 
tendon  of  the  plantaris  muscle  of  man  will  support  a  weight  of  about 
15  kilogrammes,  without  breaking.  By  resistance  to  traction,  the  tendons 
and  ligaments  accomplish  a  certain  amount  of  mechanical  work ;  some- 
times the  membranes  formed  by  the  connective  tissues  afford  support  to 


344  THE  PHYSIOLOGY  OF  THE  TISSUES. 

groups  of  muscles,  or  assist  in  giving  strength  to  the  walls  of  cavities. 
Resistance  to  pressure  is  manifested  by  the  flat  bones,  the  intervertebral 
discs,  and  the  cartilage  covering  articular  surfaces.  It  thus  assists  in  the 
maintenance  of  posture,  and  in  walking.  Resistances  to  pressiu-e  and 
torsion  are  only  exerted  in  certain  circumstances.  For  example,  when 
the  hand  supports  a  heavy  weight,  the  arm  being  horizontal,  the  bone 
tends  to  become  bent ;  in  inspiration,  the  costal  cartilages  and  ribs 
undergo  torsion,  which  ceases  during  expiration,  when  the  cartilages 
and  bones  return  to  their  previous  condition.  (Beaunis.)  The  con- 
nective tissues  also  give  cohesion  to  the  various  organs. 

The  structure  of  the  connective  tissues  is  always  related  to  the 
mechanical  uses  for  which  they  are  adapted.  As  regards  cohesion,  Ave 
find  it  to  be  determined  with  reference  to  the  direction  of  the  forces  which 
tend  to  rupture  the  tissue.  When  the  forces  act  as  pulling  forces,  the 
cohesion  is  greatest  in  the  longitudinal  direction,  and  the  structures  are 
composed  of  fibrils;  but,  if  forces  act  on  the  tissue  in  several  directions,  as 
in  fibrous  membranes,  aponeuroses,  etc.,  the  structure  is  an  irregular  net- 
work of  fibres  running  in  many  different  directions.  On  the  other  hand, 
if  resistance  to  pressure  is  to  be  attained,  as  in  the  neck  of  the  femur  or 
in  the  os  calcis,  we  find  an  arrangement  of  osseous  lamellae  so  placed  as  to 
give  the  greatest  amount  of  strength  with  the  smallest  amount  of  material. 
The  amount  of  the  connective  tissues  in  an  organ  affects  the  cohesion  of 
its  parts,  and  thus  some  organs  are  firmer  and  stronger  than  others. 
Contrast,  for  example,  in  this  respect,  the  friable  structure  of  the  liver 
with  the  tough,  fibrous  structure  of  the  lung. 

4.  Elasticity. — This  property  includes  (1)  the  change  of  form  of  an 
elastic  body  under  the  action  of  some  force ;  and  (2)  the  return  of  the 
body  to  its  original  form  when  this  force  ceases  to  act. 

The  amount  of  elasticity  is  determined  by  ascertaining  the  force  necessary  to 
change  the  form  of  the  object  to  which  the  force  is  applied,  and  the  perfection  of 
the  elastic  action  is  noted  by  the  quickness  and  accuracy  with  which  the  object 
returns  to  its  former  condition  after  the  mechanical  force  ceases  to  act.  Thus, 
when  a  strong  force  is  required  to  change  the  form  of  an  elastic  substance,  its 
elasticity  is  great ;  and,  on  the  other  hand,  when  a  feeble  force  is  sufficient  to 
overcome  the  elastic  force,  the  elasticity  is  said  to  be  small.  Again,  if,  when  the 
mechanical  force  acting  on  the  elastic  substance  ceases  to  act,  the  substance 
returns  exactly  to  its  former  condition,  its  elasticity  is  said  to  be  perfect,  while  it 
will  be  more  or  less  imperfect,  according  to  the  extent  to  which  the  substance  fails 
to  attain  its  former  dimensions.  Certain  substances  may  be  strongly  but  imper- 
fectly elastic,  as  a  silver  wire;  others  may  be  feebly  but  perfectly  elastic,  like  an 
india-rubber  band ;  while  a  third  class  are  both  highly  and  perfectly  elastic,  like 
a  steel  or  glass  rod. 

It  is  evident  that  elasticity  may  be  called  into  action  in  different  ways  accord- 
ing to  the  direction  of  the  force  acting  on  the  elastic  body.  Thus,  it  may  be 
evinced  after  pulling  or  traction,  after  squeezing  or  compression,  after  bending  or 


PROPERTIES  OF  TEE  CONNECTIVE  TISSUES.  345 

flexion,  and  after  twisting  or  torsion.  With  most  substances,  and  within  limits, 
the  lengthening  of  an  elastic  body  is  proportional  to  the  tractile  or  pulling  force. 
Above  these  limits,  the  amount  of  lengthening  is  not  directly  proportional  to 
successive  increments  of  the  tractile  force,  but  it  becomes  less  and  less  with  each 
increment.  The  amount  of  elasticity  of  torsion  is  determined  by  measuring  the 
angle  of  torsion. 

The  elasticities  of  different  bodies  are  stated  in  figures  that  express  the  modulus 
of  dasticity.  The  modulus  for  longitudinal  extension  or  compression  is  termed 
Young's  modulus,  which  may  be  defined  as  numerically  equal  to  the  pull  applied 
per  unit  cross  sectional  area  divided  by  the  elongation  per  unit  length  produced 
by  that  pull.  Let  P  be  the  pull,  a  the  cross  sectional  area,  and  let  I  be  the  length 
of  the  fibre  and  e  the  elongation  produced  ;  then — 

ejl         ta 
For  example,  it  was  found  that  a  weight  of  12700  grammes,  when  hung  on  a  steel 
wire  50.S  cm.  long  and  "0045  sq.  cm.  in  cross  sectional  area,  elongated  it  by  7  mm. 
( '7  cm. )     Hence,  for  this  wire, 

M   =    1-700/  0045   _  20(35  x  10®  grammes  weight  per  square  centimetre. 

Wertheim  gives  the  moduluses  of  the  following  substances  in  grammes  weight  per 
square  centimetre  :— Bone,  2304-1  x  lO*^ ;  tendon,  163-41  x  lO®  ;  nerves,  18-89  x  W  ; 
living  muscle  at  rest,  -95  x  10" ;  veins,  -87  x  10"^ ;  arteries,  "052  x  10".  The  latter 
figure  may  be  taken  as  the  modulus  of  elastic  tissue,  which  abounds  in  the  larger 
arteries.  Fi-om  these  figures,  we  may  calculate  the  elongation  produced  by  any 
pull  applied  (the  pull  being  within  the  elastic  limits)  thus  :    Let  P  be  the  pull 

applied —  e  =  ^   x   i 

~  M         a 
where  I  and  a  are  the  length  and  cross  section  of  the  body  stretched. 

The  connective  tissues  may  be  divided,  with  reference  to  their  elasticity,  into 
two  groups — (1)  Yellow  elastic  tissue,  which  is  feebly  but  perfectly  elastic,  that  is 
to  say,  it  changes  its  form  under  the  influence  of  feeble  force,  and  returns  exactly 
to  its  original  form  ;  (2)  the  second  group  includes  connective  tissue  properly  so- 
called,  namely,  tendons  and  ligaments,  which  are  highly  but  imperfectly  elastic, 
that  is  to  say,  they  change  form  only  under  the  action  of  powerful  forces,  and  do 
not  return  completely  to  their  original  state. 

The  elasticity  of  connective  tissues  plays  an  important  part  in  the 
body — (1)  It  is  a  permanent  force  which  resists  other  permanent  forces, 
such  as  gravity  or  muscular  action.  Thus  the  elasticity  of  the  inter- 
vertebral discs,  and  of  the  ligamenta  stihflava,  assists  in  maintaining  the 
erect  position  of  the  vertebral  column,  and  in  expiration  the  elasticity 
of  the  costal  cartilages  and  of  the  ribs  restores  the  original  form  of  the 
thorax  when  the  inspiratory  muscles  have  ceased  to  act.  (2)  Elasticity 
transforms  an  intermittent  into  a  continuous  movement;  thus,  the 
elasticity  of  the  arterial  walls  converts  the  intermittent  flow  of  the 
blood  in  the  arteries  into  a  continuous  current  in  the  capillaries,  by 
coming  into  play  in  the  intervals  between  cardiac  beats.  (3)  It  tends  to 
maintain  the  form  of  organs  against  temporary  forces  that  may 
act  on  them — traction,  pressure,  or  torsion.     (4)  Elasticity  economizes 


346  THE  PHYSIOLOGY  OF  THE  TISSUES. 

muscular  work  by  coming  into  i)lay  in  the  intervals  between  successive 
shocks.  Suppose  an  intermittent  force  acts  on  a  heavy  body  b}^  traction, 
it  has  been  found  by  experiment  that  the  introduction  of  an  elastic 
medium  between  the  heavy  body  and  the  point  at  which  the  force  is 
applied  will  enable  the  same  work  to  be  done  A^dth  a  smaller  expendi- 
ture of  force  than  if  the  force  acted  through  a  rigid  or  non-elastic 
structure.     (Marey.)^ 

2.  Vital  Properties. 

(A)  Vital  Properties  of  the  Fibrillar  Connective  Tissues. 

1.  Nutrition. — The  nutrition  of  the  connective  tissues  is  feeble — that  is 
to  say,  metabolism  is  not  ver}'  active  in  them,  except  during  the  process  of 
gi'owth.  Ordinary  areolar  tissue  is  richh'  supplied  with  vessels.  Waste 
produ.cts  are  removed  chiefl}'  b}'  the  lymphatics,  which  are  abundant. 

2.  Sensibility. — Connective  tissues  consisting  of  fibres  are  not  yqvj 
sensitive.  There  are  nerve -terminations  in  tendon  (p.  327),  but  no 
special  terminations  exist  in  ordinary  areolar  tissue.  AVhen  con- 
nective tissue  is  cut,  no  doubt  pain  may  be  caused  by  the  severance  of 
sensory  nerve-fibres  passing  through  it. 

(B)  Vital  Properties  of  Cartilage  and  Bone. 

Xo  blood-vessels  enter  hyaline  cartilage,  and  it  therefore  derives 
nourishment  from  the  vessels  of  adjoining  textures,  more  especially 
from  bone,  by  a  process  of  imbibition.  AMiere  cartilage  exists  in  large 
masses,  canals  may  be  formed  in  its  substance  for  the  conveyance  of 
blood-vessels,  but  cartilage  never  contains  a  plexus  of  capillaries. 
Cartilage  is  devoid  of  sensibility. 

The  nutrition  of  bone,  even  in  the  adult,  is  active,  as  is  shown  b}' 
the  morphological  changes  (softening,  fatty  degeneration,  etc.),  which 
it  may  undergo  in  the  course  of  disease.  The  bones  are  well  supplied 
with  blood-vessels,  derived  partly  from  periosteal  vessels,  and  partly 
from  vessels  in  the  medullary  canal.  Fine  vessels  run  through  all  parts 
of  the  compact  tissue  in  the  Haversian  canals.  From  these,  nutritious 
fluid  permeates  the  substance  of  the  bone,  by  the  canaliculi  uniting  the 
masses  of  protoplasm  (bone  corpuscles)  in  the  lacunae. 

Bone  in  the  healthy  condition  is  feebly  sensitive ;  but  when  inflamed, 
especially  near  the  periosteal  surface,  it  becomes  acutely  painful.  The 
marrow  and  periosteum  of  bone  contain  numerous  nervous  filaments, 
which  occasionally  manifest  extreme  sensibility,  as  diu'ing  the  process  of 
inflammation. 

^  Marey.  Du  moyen  d'economiser  le  travail  moteur  de  rhomme  et  des  animaux. 
Kdle  de  Telasticite  daus  les  appareils  moteurs  des  etres  vivaats.  Fhydolofjie 
Experimentale ,  1S76. 


PROPERTIES  OF  THE  CONNECTIVE  TISSUES.  347 

Cartilages  form  smooth  siu'faces  in  the  joints,  and  thus  allow  the 
various  parts  of  the  skeleton  to  move  on  each  other  "vrith  a  minimum  of 
friction,  Avhile,  by  their  consistence  and  elasticity,  they  break  the  force 
of  concussion.  Certain  of  the  permanent  cartilages  also  enter  into  the 
formation  of  the  external  ear,  the  nose,  the  eyelids,  the  Eustachian 
tube,  the  larynx,  and  the  "windpipe,  maintaining  the  form  of  these 
organs,  and  giving  attachment  to  muscles  and  ligaments. 

Bones,  in  the  adult,  form  the  frameAvork  of  the  skeleton.  Certain 
bones,  as  those  of  the  extremities,  are  the  passive  organs  of  locomotion, 
whilst  others,  when  clothed  vdih  the  soft  tissues,  form  the  ca^aties  of 
the  body,  and  serve  as  protective  structiu-es  for  delicate  organs. 


Chap.    XIII.— PHENOMENA    OF    FILTRATION    AND    OF    OSMOSIS 
IN    RELATION    TO    TISSUES. 

At  this  stage  the  student  shoidd  make  himself  familiar  with  the 
phenomena  of  filtration  and  of  osmosis,  as  these  processes  play  an 
important  part  in  the  nutrition  of  the  tissues  and  they  are  well 
illustrated  by  the  passage  of  fluids  through  the  connective  tissues.^ 

I.  Filtration  through  Organic  Membranes. 

If  we  poiu:  a  fluid  into  a  glass  cylinder,  one  end  of  which  is  covered 
by  an  organic  membrane,  and  if  the  membrane  imbibes  the  fluid,  or  a 
portion  of  it,  filtration  occiu's.  The  rapidity  of  filtration  is  in  direct 
proportion  to  the  pressiure  exerted  by  the  fluid  upon  the  membrane,  and 
it  increases  very  rapidly  with  a  rise  of  temperature.  Solutions  of 
crystalloids  pass  almost  without  change,  and  the  density  of  the  fluid 
left  behind  is  the  same  as  that  Avhich  has  passed  through  the  membrane. 
In  the  case  of  colloids,  however,  the  proportion  of  the  dissolved  sulj- 
stance  is  always  less  in  the  filtered  fluid  than  in  that  which  remains 
behind  ;  or,  in  other  words,  a  membrane  permits  the  passage  of  a  larger 
relative  quantity  of  water  than  of  colloids. 

"When  colloids  exist  in  a  fluid,  they  exert  an  influence  upon  the  filtra- 
tion of  the  salts  dissolved  in  the  same  fluid ;  the  greater  the  quantity 
of  colloidal  material  in  the  fluid  on  the  filter,  the  smaller  will  be  the 
proportion  of  the  dissolved  salts  that  passes  through  the  membrane  ; 
0I-,  in  other  words,  the  presence  of  colloidal  matter  hinders  the 
filtration  of  crystalloids.  The  filtration  of  fluids  floAving  in  vessels  is 
afi'ected  in  the  same  manner  by  pressure  and  temperature ;  but  certain 

^  The  following  has  been  prepared  largely  with  the  aid  of  Wundt's  elaborate 
account  in  his  Fhysiologie  Humaine,  p.  55. 


348 


THE  PHYSIOLOGY  OF  THE  TISSUES. 


phenomena  which  occnr  can  only  be  explained  by  assuming  special 
properties  in  some  organic  membranes. 


2.  Diffusion  through  Organic  Membranes. 

When  an  organized  membrane  is  interposed  between  two  fluids,  both 
of  which  may  be  imbibed  by  the  membrane,  and  which  are  miscible,  an 
exchange  of  the  two  fluids  takes  place  through  the  membrane,  and  this 
exchange  goes  on  until  the  two  fluids  have  the  same  composition. 
There  may  be,  however,  an  unequal  exchange  between  the  two  fluids, 
so  far  as  volume  of  water  is  concerned,  so  that  for  one  part  of  the  first 
fluid  which  passes  to  the  second,  a  smaller  quantity  will  pass  from 
the  second  to  the  first.  In  comparing  the 
diffusive  properties  of  different  fluids,  it  is 
necessary  to  make  the  experiment  at  the  same 
temperature,  and  with  one  of  the  fluids  constant 
in  composition.  Distilled  Avater  is  therefore 
employed,  in  comparative  experiments,  as  the 
standard  fluid.  Suppose  a  saline  solution  is 
placed  in  a  glass  tube,  closed  at  the  bottom  by 
an  organic  membrane,  and  the  apparatus  is 
immersed  in  a  shallow  vessel  nearly  filled  Avith 
water,  some  of  the  salt  will  be  found  after  a 
time  to  have  passed  into  the  water,  and  some  of 
the  water  aWII  have  passed  through  the  mem- 
brane into  the  tube.  Such  an  arrangement  is 
termed  an  endosmometer,  of  which  there  are 
many  forms.  One  of  simple  construction  is 
shown  in  Fig.  202.  It  Avill  also  be  found  that 
there  is  a  constant  relation  between  the  weight 
of  the  water  which  has  passed  in  the  one  direc- 
tion, and  the  weight  of  the  salt  which  has  passed 
in  the  other.  The  C[uantity  of  water  which 
passes  is  always  a  multiple,  or,  in  some  cases,  a 
through  a  coriffi 'fitted\?ght!y  fraction  of  the  quantity  of  the  substance  in  solu- 
ind  onh:"cS^r.  "T^^  tion  which  diff-uses.  The  weight  of  the  quantity 
S™eLs°on"k>e  bordtr;T  ^^  ^^^^^^^  necessary  to  replace  by  diffusion  a  unit 
of  weight  of  the  dissolved  body  (1  gramme),  is 
•called  the  endosmotic  equivalent  of  the  body.  This  equivalent  depends 
(1)  on  the  chemical  nature  of  the  body ;  and  (2)  on  the  degree  of  con- 
centration of  its  solution.  The  follomng  table,  given  by  Jolly,  shows 
the  equivalents  of  certain  substances  — 


Fig.  202.— Endosmometer.  A, 
irlass  cylinder  coustnicted  so 
that  an  organic  membrane 
(piece  of  bladder),  a,  b,  can  be 
tied  over  its  lower  end  by  the 


OSMOSIS  IN  RELA  TION  TO  TISSUES.  849 

Name  of  Substance.  Endosmotic  Equivalent, 

Chloride  of  sodium,         -------  4-0 

Sulphate  of  soda,  -          -        -        -        -        -         -        -  11 '0 

Sulphate  of  potash,         -------  12-0 

Sulphate  of  magnesia,     -         -         -         -         -         -         -  11 '5 

Sulphate  of  copper,          -------  9-5 

Sulphui-ic  acid,        --------  0"3 

Caustic  potash,        --------  200 '0 

Alcohol,           -.---.._.  4-3 

Sugar,     ----------  7-2 

That  is  to  say,  suppose  the  endosmometer  to  be  filled  Avith  solutions  of 
the  substances  in  the  above  list  and  to  be  placed  in  distilled  water, 
4  grammes  of  water  would  pass  through  the  membrane  into  the  endos- 
mometer for  1  gramme  of  chloride  of  sodium,  1 1  grammes  of  water  for 
1  gramme  of  sulphate  of  soda,  and  so  on.  Thus,  by  this  method  of 
comparison  it  can  be  shown  that  the  endosmotic  equivalent  of  chlorides 
is  small,  of  nitrates  greater,  of  bases  very  great,  of  acids  small,  and  of 
acid  salts  much  smaller  than  of  neutral  salts. 

As  Jolly,  in  these  experiments,  took  no  account  of  the  degree  of  con- 
centration of  the  fluids,  and  as  he  always  employed  dried  membranes, 
these  figures  do  not  show  the  quantities  of  these  substances  which 
would  pass  through  organic  membranes  in  the  living  state.  Hofmann 
has  shown  also  that  the  amount  of  water  of  hydration  or  of  crystalliza- 
tion, even  in  the  same  salt,  influences  to  a,  remarkable  extent  the 
endosmotic  equivalent. 

When  more  water  passes  towards  the  salrae  solution  than  the  amount  of  the 
latter  which  enters  the  water,  the  diffusion  is  said  to  be  iwiitive,  and  negative  when 
the  reverse  is  the  case.  With  alkalies  positive  endosmosis  is  strong  ;  with  acids, 
negative  endosmosis  is  the  rule,  while  salts  are  positive  and  range  between  the  two 
extremes.  When  endosmosis  is  positive,  the  equivalent  increases  with  the  degree 
of  concentration  ;  when,  on  the  contrary,  it  is  negative,  the  equivalent  dimmishes 
as  the  concentration  increases.  Thus,  in  the  diffusion  of  sulphuric  acid  with  water, 
more  acid  will  pass  into  the  water  as  the  acid  becomes  concentrated  ;  but,  on  the 
contrary,  in  the  diffusion  of  potash  with  water,  more  water  will  pass  into  the 
potash  as  the  latter  is  concentrated.  According  to  Ludwig,  sulphate  of  soda  is 
an  exception  amongst  bodies  showing  a  positive  endosmosis,  as  its  equivalent 
diminishes  by  concentration. 

Diffusion  occurs  with  a  constant  raindity  so  long  as  the  solution  has  the  same 
concentration,  and  as  the  temperature  remains  the  same. 

(a)  Effects  of  the  Degree  of  Concentration. — The  rapidity,  however,  does  not  depend 
only  upon  the  endosmotic  equivalent,  but  also  upon  the  solubility  of  the  substance 
and  its  chemical  composition.  It  increases  with  concentration.  When  saline 
solutions  diffuse  into  water,  the  rapidity  with  which  the  salt  passes  towards  the 
water,  as  well  as  that  with  which  the  water  passes  to  the  salt,  increases  with  the 
degree  of  concentration,  but  not  at  the  same  rate.  The  rapidity  with  which  the 
water  passes  to  the  salt  becomes  greater,  whilst  the  rapidity  with  which  the  salt 


350  'I'lil'^  PHYSIOLOGY  OF  THE  TISSUES. 

passes  to  the  water  remains  near-ly  proportional  to  the  degree  of  concentration. 
Thus  it  follows  that  the  more  a  solution  approaches  saturation,  the  greater  is  the 
quantity  of  water  which  passes  in  the  same  time. 

[h)  Effects  of  Ttmptralnre. — As  the  temperature  increases,  the  rapidity  of  the 
diffusion  also  increases,  and  the  rapidity  of  diffusion  increases  more  rapidly  as  the 
temperature  rises.  This  will  be  seen  in  the  following  table,  given  by  Eckhard, 
showing  the  rapidity  with  which  common  salt  passed  through  the  fresh  peri- 
cardium of  an  ox  in  the  same  time  with  an  increasing  temperature  : — 

Temperature  in  Quaiititj'  of  Common 

Degrees  C.  Salt  which  passed. 

8-0, 0-303 

9-6, 0-364 

13-8, 0-396 

18-3, 0-474 

22-5, 0-549 

•26-0, 0-628 

(c)  Effects  of  a  Mixture  of  Saline  Matters. — When  a  solution  dififuses  through  a 
membrane  not  only  with  water,  but  with  a  solution  of  the  same  or  of  a  different 
substance,  that  is,  where  two  solutions  of  the  same  substance  or  of  difl'erent  sub- 
stances, are  on  opposite  sides  of  the  membrane,  the  diffusion  depends  partly  on  the 
degree  of  concentration  of  the  two  solutions,  and  partly  upon  the  chemical  properties 
of  the  two  bodies  dissolved.  Suppose  two  solutions  of  the  same  substance,  biit  of 
unequal  degrees  of  concentration  ;  the  more  concentrated  solution  will  diminish, 
while  the  more  dilute  will  increase  in  density.  In  this  case,  the  endosmotic 
equivalent  has  a  constant  value.  On  the  other  hand,  the  rapidity  of  diffusion  will 
be  in  the  inverse  ratio  of  the  difference  of  concentration  of  the  two  fluids  present ; 
that  is  to  say,  as  the  initial  difference  of  concentration  of  the  two  fluids  diminishes, 
the  rapidity  of  difi"usion  will  also  become  less. 

(d)  Nature  of  Siibstance. — All  colloidal  substances  in  solution  pass  with  great 
difficulty  through  organized  membranes.  Such  bodies  attract  water,  so  that,  when 
their  solution  diffuses  with  this  fluid,  there  is  a  positive  current  of  water.  The 
endosmotic  equivalent  of  these  substances  is  very  high,  but  on  the  other  hand  the 
rapidity  of  their  diffusion  is  low.  Albumin  in  solution  has  a  stronger  endosmotic 
affinity  for  saline  solutions  than  for  water,  and  the  cui'rent  of  albumin  increases 
very  rapidly  with  concentration  of  the  saline  solution.  When  a  mixture  of 
colloidal  bodies  in  a  fluid  along  with  some  crystalloids  is  permitted  to  diffuse  into 
water,  none  of  the  colloidal  matters  passes  through  the  membrane.  Thus  from  a 
solution  of  gum,  albumin,  and  sugar,  none  of  the  first  two  will  pass,  but  the  sugar 
will  pass  through  with  great  ease.  There  is  thus  a  kind  of  mechanical  separation 
of  the  substances.  To  this  general  rule,  however,  there  is  one  exception,  namely, 
when  by  the  diffusion  of  a  substance  mixed  with  colloidal  matters,  there  is  pro- 
duced on  the  other  side  of  the  membrane  a  liquid  toward  which  the  colloidal 
matter  has  a  great  tendency  to  diffuse.  Thus  when  a  mixture  of  albumin  with 
common  salt  is  exposed  to  diffusion  into  water,  the  salt  alone  at  first  passes  through 
the  membrane,  but  when  the  water  on  the  other  side  of  the  membrane  contains  a 
certain  amount  of  salt,  the  albumin  then  dififuses  with  considerable  intensity.  Von 
Wittich  and  Funke  have  studied,  as  regards  diflfusion,  the  differences  of  solutions 
of  various  albuminoids,  and  they  have  found  that  of  these  bodies,  peptones  possess 
the  property  of  diflfusibility  to  the  greatest  extent. 


OSMOSIS  IN  RELA  TION  TO  TISSUES. 


351 


(e)  Effects  of  Electric  Currents. — A  continuous  electric  current  passed  through  a 
fluid,  in  a  diffusion  apparatus,  affects  diffusion ;  the  quantity  of  fluid  situated  on 
the  side  of  the  negative  pole  increases,  whilst  that  on  the  side  of  the  positive  pole 
diminishes.  The  mass  of  fluid  moves  in  the  direction  of  the  positive  current,  and 
the  quantity  of  fluid  carried  away  is  always  greater  as  the  fluid  is  easy  to  move 
and  as  the  galvanic  current  is  more  intense,  and  the  amount  is  independent  of  the 
nature  of  the  surface  and  of  the  thickness  of  the  porous  plate. 

When  water  is  allowed  to  diffuse  with  a  saline  solution,  and  a  galvanic  current 
is  directed  through  the  two  liquids  from  the  water  to  the  salt,  more  water  will 
pass  to  the  saline  solution  than  would  have  passed  if  the  current  had  not  been 
there.  If  now  the  direction  of  the  current  be  changed,  so  as  to  pass  from  the  salt 
to  the  water,  more  salt  will  then  pass  towards  the  water,  or,  in  other  words,  the 
osmotic  action  has  been  inverted  by  the  galvanic  current. 

Albumin  is  found  in  the  body,  combined  with  alkalies,  as  albuminate  of  soda  or 
of  potash,  and  it  behaves  in  these  compounds  as  a  feeble  acid.  Suppose  that 
albumin  and  saline  matters  are  submitted  to  diffusion  with  water,  and  that  at  the 
same  time  a  current  is  passed  through  the  solutions,  it  will  be  found  (1)  if  the 
positive  current  be  directed  from  the  solution  of  albumin  towards  the  water,  salts 
will  pass  from  the  side  of  the  water,  and  albumin  will  remain  near  the  positive 
pole  ;  (2)  if  the  current  pass  from  the  water  to  the  albuminous  solution,  water  will 
pass  to  the  albuminous  solution,  and  albumin  will  pass  through  the  membrane  into 
the  water,  and  will  be  deposited  near  the  positive  pole.  The  albumin  then  be- 
haves as  acids  do,  having  passed  from  the  negative  towards  the  positive  pole. 
These  interesting  facts,  ascertained  by  Von  Wittich,  indicate  the  possibility  of  the 
physical  phenomena  of  nutrition  being  affected  by  a  continuous  galvanic  current, 
and  they  suggest  many  researches  of  therapeutical  importance. 

(/)  Eature  of  Orgcmic  Membrane. — The  nature  of  the  membrane  affects  os- 
motic action.  Dry  membranes  have  always  a  higher  endosmotic  equivalent  than 
those  which  are  fresh  or  wet.  In  comparing  organic  membranes  of  different  struc- 
ture, it  is  found  that  the  dimensions  of  their  pores  have  an  important  influence, 
just  as  is  known  to  be  the  case  in  diffusion  through  plates  of  clay.  Buchheim  has 
shown  that  for  a  membrane  with  large  pores,  the  endosmotic  equivalent  of  a  salt 
is  smaller  as  the  affinity  of  this  salt  for  water  is  greater,  while,  on  the  other  hand, 
for  very  dense  membranes,  the  equivalents  are  proportional  to  the  affinity  of  the 
salts  for  water.  The  following  table  by  Harzer  shows  the  variations  of  endosmotic 
equivalents  for  different  membranes — 


Ox 

Bladder. 

Pig's 
Bladder. 

Ox  Peri- 
cardium. 

Collodion 
Membrane. 

Chloride  of  sodium,     - 
Chloride  of  potassium, 
Sulphate  of  soda,  -       -       -       - 
Sulphate  of  potash. 

6-460 

5-601 

18-764 

13-908 

4-335 

12-231 
11-700 

4-000          10-200 
3-891          13-632 
8-915            6  097 

8-181            4-147 

1 

Of  all  of  these  membranes,  that  formed  of  collodion  is  the  most  dense ;  the 
bladders  of  the  ox  and  the  pig  are  both  less,  and  the  pericardium  of  the  ox  occupies 
a  mean  position.  The  sulphates  have  a  much  stronger  affinity  for  water  than  the 
alkaline  chlorides. 


All  the  phenomena  of  osmosis  may  be  attributed  to  the  following 
causes  :  (1)  to  a  force  of  attraction  of  two  fluids,  the  one  for  the  other  ; 


352  THE  PHYSIOLOGY  OF  THE  TISSUES. 

( 2)  to  a  relative  attraction  that  the  substance  forming  the  membrane 
exercises  upon  the  two  liquids  in  dift'usion — a  force  which  determines 
the  mode  in  which  liquids  pass,  and  the  rapidity  with  which  they  pass, 
through  small  porous  canals ;  (3)  to  the  narrowness  of  the  pores  through 
which  the  liquids  pass  ;  and  (4)  to  the  diminution  of  adhesion  of  the 
liquid  to  the  wall  of  the  porous  canals,  by  reason  of  elevation  of  tem- 
peratiire.  Briicke  was  the  first  to  attribute  the  phenomena  of  diffusion 
to  an  attraction  betAveen  the  walls  of  canals  and  water. 

The  importance  of  applying  these  facts  regarding  filtration  and  os- 
mosis to  the  phenomena  of  the  nutrition  of  living  tissues  is  becoming 
more  and  more  recognized.  In  the  present  state  of  our  knowledge, 
however,  it  is  impossible  to  follow  all  the  stages  of  the  process,  and  we 
can  only  make  general  statements. 

The  connective  tissues  are  surrounded  on  all  sides  by  fluids  such  as 
blood,  serous  transudations,  and  lymph.  These  fluids  may  be  regarded 
as  saline  solutions  of  albuminous  matters,  or  as  solutions  containing 
both  crystalloids  and  colloids.  The  fluids  are  imbibed  by  the  connec- 
tive tissues  just  as  they  would  be  taken  up  by  porous  substances,  by  a 
process  which  may  be  called  capillary  imbibition.  But  when  the  fluids 
reach  the  ultimate  tissues  in  the  form  of  protoplasmic  masses,  or  of 
protoplasm  more  or  less  modified,  we  have  to  deal  with  a  homogeneous 
structure  containing  no  pores.  Here  an  interchange  occurs  between 
the  fluid  and  the  tissues  by  a  kind  of  molecular  imbibition,  a  process 
somewhat  similar  to  that  by  which  a  membrane,  as  above  stated,  allows 
osmotic  phenomena  to  occur.  Molecular  imbibition  possesses  the  two 
following  characters  :  (1)  When  a  tissue  imbibes  a  fluid,  it  usually 
increases  in  volume,  but  this  increase  does  not  always  correspond  to  the 
quantity  of  the  fluid  imbibed,  and  in  some  cases  actual  diminution  in 
size  of  the  mass  of  tissue  may  occur  after  imbibition  ;  and  (2)  tissues 
imbibe  more  distilled  water  than  water  containing  saline  substances, 
and  consequently  the  fluid  which  is  imbibed  by  a  membrane  \nll  be  less 
concentrated  than  the  fluid  in  which  the  membrane  is  immersed.  This 
probably  explains  why  serous  effusions  are  in  general  less  concentrated 
than  the  plasma  of  the  blood.     (Beaunis.) 

The  passage  into  the  tissues  of  part  of  the  plasma  of  the  blood 
through  the  thin  walls  of  the  capillaries,  under  the  influence  of  blood 
pressure,  is  an  example  of  filtration.  The  greater  the  amount  of  pres- 
sure exerted  in  the  vessels,  the  greater  will  be  the  amount  of  fluid 
forced  through  their  walls.  A  similar  phenomenon  is  seen  in  the 
separation  of  water  and  saline  matters  from  the  blood  in  the  Malj)ighian 
bodies  of  the  kidney,  where  the  blood  passes  under  considerable  pres- 
sure through  a  complicated  arrangement  of  minute  vessels.     Colloidal 


OSMOSIS  IN  RELA  TION  TO  TISSUES.  358 

matters,  such  as  albumin,  in  these  circumstances  pass  with  difficulty, 
and  only  under  strong  pressure,  whereas,  on  the  other  hand,  crystalloids 
pass  more  readily,  and  under  feeble  pressure.  Any  circumstances, 
therefore,  which  increase  beyond  a  certain  limit  the  pressure  in  the 
vessels,  may  be  attended  by  the  appearance  of  albumin  in  the  urine. 

It  is  to  be  especially  noted  that  in  the  living  body  we  rarely  find  the 
conditions  of  osmotic  phenomena  so  simple  as  to  consist  of  a  fluid  on 
each  side  of  a  membrane,  and  each  under  the  same  pressure.  Almost 
invariably  one  of  the  fluids  is  under  a  greater  pressure  than  the  other, 
and  thus  the  interchange  that  takes  place  must  be  due  partly  to  filtra- 
tion and  partly  to  osmotic  action.  In  'addition  it  is  possible  that 
there  may  be  some  kind  of  attractive  influence  exerted  by  the  living 
tissues  themselves,  and  thus  the  process  by  which  they  obtain  fluid 
pabulum  becomes  more  complicated.  A  special  influence  of  this  kind, 
to  be  remembered  in  studying  secretion,  by  which  certain  matters  are 
removed  from  the  blood,  is  the  selective  activity  of  ej)ithelial  cells,  of 
which  examples  will  be  given  in  treating  of  secretion. 

3.  Absorption  of  Gases  by  Moist-Organized  Membranes, 
and  by  Fluids. 

Difiusion  between  gases  and  liquids  is  not  modified  in  its  essential 
points  by  the  interposition  of  a  wet  organic  membrane.  The  coefficient  of 
absm-ption  of  a  gas  is  the  volume  dissolved  by  one  volume  of  water  at  0°  C. 
and  760  mm.  pressure.  The  quantity  of  gas  exchanged  between  two  gases 
on  opposite  sides  of  a  membrane,  one  of  them  being  dissolved  in  a 
fluid,  depends  partly  on  the  coefiicient  of  absorption  of  the  gas  and 
partly  on  the  pressure  of  the  gases  on  opposite  sides  of  the  membrane. 
A  gas  which  possesses  a  large  coefficient  of  absorption,  such  as  carbonic 
acid,  is  absorbed  by  a  wet  membrane  in  greater  quantity  than  oxygen, 
hydrogen,  or  nitrogen.  The  amount  of  absorption  diminishes  with 
elevation  of  temperature  and  with  diminution  of  pressure.  Absorp- 
tion of  gas  by  a  liquid  depends  upon  the  pressure  of  the  gas  on  the 
surface  of  the  liquid ;  the  greater  the  pressure  the  greater  is  the 
amount  of  gas  absorbed  by  the  fluid.  When  a  state  of  equilibrium 
between  the  tension  of  the  gas  in  the  fluid  and  the  pressure  of  the 
external  gas  is  attained,  absorption  ceases.  If  the  pressure  of  the 
external  gas  diminishes,  and  the  tension  of  the  gas  in  the  fluid  increases, 
a  portion  of  the  gas  dissolved  in  the  fluid  will  pass  into  the  exter- 
nal gas  until  a  state  of  ec[uilibrium  of  pressure  is  re-established.  Again, 
if  a  mixture  of  gases  be  exposed  to  a  liquid,  each  gas  is  dissolved 
independently  of  the  others,  in  proportion  to  its  partial  pressure.  There 
I.  z 


354  THE  PHYSIOLOGY  OF  THE  TISSUES. 

is  thus  a  state  of  continual  gaseous  exchange  established  between  fluids 
of  the  body  in  Avhich  gases  are  dissolved  and  the  external  atmosphere. 
This  process,  as  we  shall  hereafter  see,  is  the  essential  phenomenon  in 
respiration,  as  it  occurs  in  the  ultimate  air  cells  of  the  lung.  It  is 
highly  probable  that  the  same  physical  explanation  may  be  given  of  the 
interchange  of  gases  Avhich  constantly  occurs  between  the  gases  dis- 
solved in  the  blood  and  those  set  free  in  living  tissues,  as  one  of  the 
ultimate  chemical  products  which  are  the  result  of  their  vital  activity.^ 

^  Consult,  regai'ding  the  laws  of  absorption  and  of  diffusion  of  gases,  Wundt's 
Physique  Medicate,  p.  201. 


355 


SECTION  IV. 


THE  CONTRACTILE  TISSUES. 


acl'L 


The  phenomenon  of  contractility  is  exhibited  by  various  cells,  such  as 
the  colourless  corpuscles  of  the  blood,  connective  tissue  corpuscles,  the 
■corpuscles  of  lymph,  and  the  corpuscles  of  pus.  These  amo3boid  cells, 
when  examined  T\dth  sufficiently  high  power,  manifest  a  slow  circulation 
of  the  granules  lying  in  the  protoplasm,  and  also  slow  changes  of  form, 
such  as  have  been  already  described  in  treating  of  that  substance. 
They  have  been  seen  to  take  up  into  their  substance  small  particles  of 
pigment,  such  as  carmine,  indigo, 
and  aniline,  and  even  globules  of 
milk.  Contractile  bodies  may 
wander  through  the  interstices 
of  the  tissues,  a  phenomenon 
termed  the  migration  of  cells. 
Contractility,  however,  is  more 
especially  manifested  by  muscu- 
lar fibre,  which  is  arranged  to 
build  up  the  chief  portion  of  the 
organs  termed  the  muscles,  and 
whichalso  exists  in  the  coats  of  the 
hollow  viscera  and  of  the  vessels. 

Our  knowledge  of  the  physio- 
logical properties  of  muscles  has 
been  largely  derived  from  the 
study  of  the  living  muscles  of  the 
frog.  These  retain  their  vitality 
long  after  the  death  of  the  ani- 
mal. The  physiological  student 
should    make    himself    familiar 


Fig.  203. — Muscles  seen  on  the  anterior  aspect  of  a 
frog's  hinder  limb,     s,   sartorius ;    adJ,    adductor 
longus ;  v.i.,  vastus  intemus;  ex.,  extensor  cruris  ; 
with  the  general  anatomy  of  the    *•«•>  tiWalis  anticus  ;  f.t.,  flexor  tarsi ;  t.p.,  tibiaUs 

muscles  of  the  hinder  limb  of  the 


frog,  as  shown  in  Fig.  203. 


posticus ;  g.e.,  gastrocnemius  ;  r.i'.,  rectus  internus 
major  or  gracilis,  or  adductor  magnus  ;  r.i".,  rectus 
intemus  minor  or  cutaneus  ;  ad'",  adductor  mag- 
nus :  ad"  adductor  brevis. 


356 


THE  CONTRACTILE  TISSUES. 


Chap.  I.— THE  SPECIAL  STRUCTURE  OF  MUSCLES  AND  THEIR 
RELATIONS  TO  NERVES. 

In  the  lower  forms  of  invertebrate  beings,  the  contractile  elements 
consist  of  filiform  processes  of  cells  situated  in  the  endoderm  or  in  the 
ectodeiTa.  Such  cells,  first  described  by  Kleinenberg,  are  termed  myo- 
epithelial  cells  (Figs.  204  and  205).     The  epithelial  portion  of  the  cell 


Fig.  205.— Myo-epithelial  cells  of  Hydra_ 
Fio.    204.— Muscle  cells  from    Lizzia    Kollikeri.      The  ">,  vi,  muscular  fibres. 

elongated  upper  cell  is  from  the  circular  fibres  of  the 
subumbrella  ;  the  two  lower  cells  are  myo-epithelial  cells 
from  the  base  of  a  tentacle. 

may  become  so  much  reduced  in  size  as  to  leave  only  the  nucleus  sui'- 
rounded  by  a  thin  layer  of  protoplasm,  but  the  elongated  process  or  fibre 
remains,  and  thus  a  layer  of  muscular  tissue  may  be  formed  immediately 
below  the  surface. 

According  to  F.  M.  Balfour^ 
the  muscular  elements  of  the 
higher  groups,  including  mam- 
mals, also  belong  to  the  myo- 
epithelial type.  Embryonic 
muscle  cells  are  at  first  epi- 
thelial cells;  they  become 
spindle-shaped ;  part  of  the 
protoplasm  is  diflerentiated 
into  striated  muscular  fibres, 
and  the  undifi'erentiated  part 
seen  around  the  nucleus  is  the 
epithelial  element  of  the  cells. 
By  further  division,  the  number 
of  fibrils  in  each  cell  increases, 
so  that  a  primitive  bundle  is 
formed,  which  is  surrounded 
by  a  sheath  or  sarcolemma. 
The  chief  part  of  the  muscular 
sj'stem  of  the  trunk  is  formed 
from  the  mesoblast,  which,  as- 


\^- 


Fig.  206.— Portion  of  a  transverse  section  of  a  muscle 
of  the  thigh  (adductor)  of  a  rabbit,  x  60  d.  P,  peri- 
mysium internum,  containing  at  g  two  blood-vessels 
cut  across.  //;,  muscle  fibres  ;  they  have  in  many  places 
separated  from  each  other  so  that  we  can  perceive  p, 
the  perimysium  oi  individual  muscle  fibres.  At  :r  a 
transverse"  section  of  a  muscle  fibre  has  fallen  out. 
(Method  Xo.  65,  Appendix.) 


MUSCLES  AND  THEIR  RELATIONS  TO  NERVES.         357 

already  shown,  is  derived  primarily  from  the  epiblast,  and  thus  the 
epithelial  origin  of  muscle  becomes  apparent. 

The  structure  of  muscular  tissue  has  already  been  described  in 
treating  of  cells,  but  before  considering  the  functions  of  the  tissue, 
we  shall  give  an  account  of  the  mode  of  union  of  the  fibres  so  as  to 
form  muscles,  the  mode  of  connection  of  the  fibres  with  tendons,  the 
arrangement  of  the  blood-vessels,  and  the  manner  in  which  the  nerves 
terminate  in  muscle. 

(1)  Formation  of  a  Muscle. — The  muscular  fibres  nm  side  by  side,  and 
they  are  held  together  by  sheaths  of  loose  connective  tissue.  Xeigh- 
bouring  muscular  fibres  never  come  into  direct  contact,  but  each 
individual  fibre  is  surrounded  by  its  o^\^\  sheath,  the  sarcolemma.  A 
bundle  of  such  fibres  m.ay  be  enclosed  by  a  sheath  of  connective  tissue, 
termed  the  perimysium  intermim,  and  a  number  of  such  bundles  constitutes 
a  muscle,  which  is  surrounded  by  a  thicker  layer  or  sheath  of  connective 
tissue,  the  perimysium  externum^  The  internal  peri- 
mysium communicates  with  the  external  at  many 
places,  and  thus  a  transverse  section  of  a  muscle 
shows  the  appearance  depicted  in  Fig.  206.  The 
perimysium  consists  of  fibrillar  connective  tissue 
and  elastic  fibres.  It  occasionally  contains  fat 
cells,  and  it  is  the  bearer  of  the  nerves,  blood- 
vessels, and  lymphatics.  The  perimysium  inter- 
num, has  ramifying  upon  it  only  capillaries  and  the 
delicate  terminations  of  nerves. 

(2)  Connect'wn  of  Muscular  Fibres  icith  Tendon. — 
The  perimysium  of  individual  bundles  of  fibres  be- 
comes continuous  with  the  connective  tissue  fibres 
forming  the  tendon,  and  the  sarcolemma  ends  at 
the   termination   of  the   striated   muscular   fibre  fig.  207.— Portion  of  a  longi- 

._,.        nA^7\  tudinal  section  of  the  gas- 

<rlg.   207).  trocnemtus  muscle  of  a  frog, 

(3)  Blood  and  Lymph  Vessels. — The  blood-vessels  mysiumof  a  single  muscle 

f.     ,    .    ,     1  1  rm  •^      fibre,  seen  from  the  side ;  at 

01  striated  muscles  are  very  numerous.     Ihe  capii-  j,',  seen  from  the  surface  as 

1      •  ,,1  J.JTJ.-J.11  transverse  lines ;  7ii,  muscle 

lanes  are  amongst  the  most  delicate  m  the  human  fibres.  (Method  Xo.  m,  Ap- 
body,  and  they  form  a  netting  of  elongated  rect-  p®'^'^^^- 
angular  meshes  (Fig.  171,  p.  312).     The  capillaries  are  always  outside 
the  sarcolemma.     The  lymphatics,  also  numerous,  run  alongside  of  the 
ramifications  of  the  smaller  blood-vessels. 

(4)  Involuntary  or  Non-Striated  Muscles. — Involuntary  or  non-striated 
muscle  fibres  are  bound  very  firmly  together  by  a  structureless 
cement  substance.  Septa,  or  partitions  between  bundles,  composed  of 
connective  tissue,  occur  only  at  very  great  intervals  (Fig.  208).     The 


358 


THE  CONTRACTILE  TISSUES. 


union  is  either  such  as  to  form  parallel  fibrous  membranes,  as  in  the 
muscular  layers  of  the  intestinal  canal,  or  a  comj)licated  net- 
Avork  of  fibres,  as  in  the  wall  of  the  urinary 
bladder  or  uterus.  The  larger  blood-vessels  run 
in  the  septa  of  connective  tissue ;  the  capil- 
laries, on  the  contrary,  penetrate  between  the 
indiAddual  fibres  and  form  an  elongated  capil- 
lary network.  The  Ij-mphatics,  pursuing  a 
similar  coiu'se,  are  present  in  considerable 
numbers. 

(5)  Termination  of  Nerves  in  Muscle. — The 
nerves,  ramifying  over,  or  among  the  fasciculi, 
of  a  muscle,  divide  and  sul^divide  until  numerous 
minute  branches  are  formed.  These  form  a 
plexus,  the  intermuscular  nerve-plexus.  From 
these  small  branches,  very  minute  branches  arise,  each  consisting  of 
one  single  medullated  nerve-fibre,  and  these  end  in  individual  muscular 
fibres.  A  nerve,  when  it  enters  a  muscle,  does  not  contain  as  many 
fibres  as  there  are  fibres  in  the  muscle.    In  the  muscle,  the  axis  cylinder 


Fig.  208. — Portion  of  a  trans- 
vei-se  section  of  the  circulur 
muscular  layer  in  the  humaii 
intestine,  x  560  d.  m,  smooth 
muscle  fibres  the  nuclei  of 
which  are  ti-ansversely  divided 
at  k.  6,  septum  of  connective 
tissue.  (Method  No.  ti7,  Ap- 
pendix.) 


Fig.  209. — Alotor  nerve-ending  from  the  mus- 
cular fibre  of  the  intercostal  muscle  of  a 
hedgehog,  x  240  d.  The  transverse  stria- 
tion  of  both  fibres  is  not  everywhere  visible. 
On  the  left  muscle  fibre  there  are  flat  connec- 
tive tissue  cells,  Z  showing  clear  nuclei.  A', 
medullated  nerve  fibres  subdividing ;  the 
marrow  is  not  recognizable  by  the  method  of 
making  the  preparation  ;  P,  end  plates. 
(Method  No.  68,  Appendix.) 


Fio.  210.— Motor 
nerve-ending  of 
a  muscular  fibre 
in  one  of  the 
muscles  of  the 
eyeball  of  a  rab- 
bit, X  240  d. 
N,  medullated 
nerve  fibre  ;  K, 
nuclei  of  the 
disc.  The  trans- 
verse striation 
of  the  fibre  is 
seen  only  in  the 
lower  half  of  the 
figure.  (Method 
No.  69,  Appen- 
dix.) 


divides  again  and  again  until  there  are  as  many  nerve  fibres  as  muscular 
fibres.  When  the  ultimate  nerve  fibre  approaches  the  muscular  fibre, 
the  nerve  fibre  loses  the  white  substance  of  Schwann,  and  the  axis 
cylinder  of  the  nerve  fibre  pierces  the  sarcolemma  and  terminates  in 
the  muscular  fibre,  in  what  is  termed  a  motor  end  plate.  These  end 
plates  vary  in  form  and  general  appearance.     Sometimes  they  seem 


MUSCLES  AND  THEIR  RELATIONS  TO  NERVES. 


359 


to  consist  of  very  minute  fibres,  formed  by  the  splitting  up  of  the  axis 
cylinder,  anastomosing  so  as  to  form  a  network,  but  usually  they  take 
the  form  of  irregularly  shaped  granular  masses  or  discs,  containing 
numerous  vesicular  nuclei. 

The  end  plates  in  the  muscle  of  mammalia  range  in  diameter  from 
39  to  60  yu,  while  they  also  vary  in  thickness.  The  nuclei,  from  4  to 
9  ;a  in  breadth,  often  contain  several  nucleoli.  It  is  important  to 
note  the  intimate  union  existing  between  the  nervous  and  muscular 
tissues.  Indeed  the  one  blends  into  the  other.  Kiihne  has  pointed  out 
that  the  axis  cylinder  spreads  out  into  a  pale  slightly  granular  sub- 
stance having  truncated  processes,  and  that  the  central  part  of  the 
axis  cylinder  forms  a  kind  of  neural  eminence  or  swelling  within  this 
expansion.     (See  Figs.  211  and  212.)     It  is  not  improbable  that  the 


Fig.  211. — Two  muscular  fibres  from  the  psoas  of  a  guinea- 
pig,  showing  the  terminations  of  the  nerves,  a,  b,  the 
primitive  fibres  with  their  transition  into  the  terminal 
plates,  e,f;  c,  neurilemma  with  nuclei,  d,  d,  continuous 
with  the  sarcolemma,  g,  g  \  h,  h,  nuclei  in  muscle. 


finest  fibrils  may  end  in  the  anisotropous  portion  of  the  muscular  fibre. 
In  many  fishes  and  amphibians  no  such  end  plates  exist,  and  in  their 
stead  we  find  the  axis  cylinder,  after  it  has  perforated  the  sarcolemma, 
dividing  into  delicate  fibrils  which  coiu-se  longitudinally  within  the 
muscular  fibre,  showing  isolated  nuclei  here  and  there,  and  ultimately 
blending  with  the  contractile  substance  of  the  fibre. 


860 


THE  CONTRACTILE  TISSUES. 


The  blending  of  the  neural  and  nuiscular  structures,  as  shown  in  cer- 
tain invertebrates,  is  also  well  illustrated  by  C'arnoy  in  Fig.  213. 


:if%' 


'f 


Fig.  212.— a  muscle  fibre,  a, 
from  a  lizard  ;  6,  nerve  fibre ; 
c,  dichotomous  division  in 
the  end  plate,  with  transition 
into  the  true  end-organ  or 
plate  of  Kiihne,  d,  d. 


Pig.  213. — Fusion  of  a  nerve  with  a 
muscular  cell  in  a  chrysalis  of  a  fly, 
showing  the  so-called  plaque  or  emin- 
ence of  Doyere.  'iie,  nerve,  showing 
small  polar  cells ;  pr,  protoplasmic 
mass,  formed  by  the  fusion  of  the  reti- 
culum or  network  in  the  muscular  fibre 
with  the  part  of  the  nerve  coming  into 
contact  with  it,  showing  numerous 
nuclei,  n  ;  m,  s,  neurilemma  fused  with 
sarcolemma  ;  t,  strias  formed  by  the 
transverse  fibres  of  the  muscular  net- 
work ;  /",  longitudinal  striatinns  ;  my, 
myosin  in  the  meshes  of  the  network  ; 
/,  lighter  coloured  portions  of  the  fibre 
formed  of  a  reticulum  the  meshes  of 
which  do  not  contain  myosin. 

Muscles  also  contain  sensory  nerve  fibres,  but  their  mode  of  origin 
has  not  been  satisfactorily  made  out. 

The  nerve  terminations  in  involuntary  or  non-striated  muscle  consist 
of  delicate  networks,  from  which  more  delicate  fibrils  arise,  and  the 
latter  have  been  satisfactorily  traced  into  the  interior  of  the  fusiform 
cells  forming  this  variety  of  muscular  tissue. 


Chap.  II.-THE  CHEMICAL  CONSTITUTION  OF  MUSCULAR  FIBRE. 

Muscular  fibre  is  composed  of  two  parts — (1)  muscle-plasma,  which 
may  be  separated  by  pressure  from  muscle  removed  from  a  recently 
killed  cold-blooded  animal,  as  a  neutral  or  slightly  alkaline  gelatinous 
fluid ;  and  (2)  a7i  insoluble  residue,  consisting  probably  of  sarcolemma, 
nuclei,  fat,  and  matters  derived  from  the  vessels,  nerves,  and  lymphatics 


CHEMICAL  CONSTITUTION  OF  MUSCULAR  FIBRE.       361 

mixed  with  the  muscular  tissue.  The  sarcolcmma  is  unaffected  by 
acetic  acid,  but  it  is  dissolved  slowly  when  heated  with  dilute  solutions 
of  the  acids  or  alkalies.  Hence  it  is  believed  to  be  of  the  nature  of 
elastin.  Nothing  is  known  regarding  the  chemical  composition  of  the 
disdiaclasts  as  distinguished  from  the  fundamental  matter  of  the  fibre. 
The  muscle-plasma  may  be  obtained  by  compression  at  a  low  tempera- 
ture (7°  to  10°  C.)  of  muscles  deprived  of  blood.  The  plasma  is  yielded 
by  the  isotropous  portion  of  the  fibre.  It  is  an  alkaline,  colourless,  or 
faintly  yellow  fluid  or  syrup  containing  various  albuminates.  When 
obtained  pure,  it  speedily  coagulates  and  separates  into  two  portions — 
muscle-clot  or  myosin  and  muscle-serum.  Coagulation  is  accelerated  by 
heat,  distilled  water,  weak  acids,  ammonia,  etc.,  and  it  is  retarded  by 
cold.  Myosin  is  an  albuminous  body,  soluble  in  5  to  10  per  cent, 
solutions  of  common  salt  or  in  weak  hydrochloric  acid.  Acids,  such  as 
•1  per  cent,  of  hydrochloric  acid,  convert  it  into  an  allied  substance 
named  syntonin,  which  is  not  soluble  in  common  salt  nor  in  a  solution  of 
sulphate  of  magnesia. 

Muscle-serum  contains  the  following  substances — 

(1)  Albuminates,  such  as  albuminate  of  potash,  which  is  precipitated 
on  heating  from  20°  to  45°  C,  and  by  neutralizing  the  alkaline  fluid. 
This  proteid  is  not  myosin,  inasmuch  as  it  is  not  soluble  in  weak 
solutions  of  common  salt.  There  exists  also  an  alkaline  potassium 
albuminate  precipitated  from  muscle-serum  when  it  is  rendered  acid. 
Serum  albumin  is  precipitated  when  the  fluid  is  rendered  acid  and 
heated  up  to  75°  C.    (Kiihne.   For  Halliburton's  results,  see  Appendix  11.) 

(2)  Traces  of  ferments,  namely,  pepsin,  ptyalin,  and  a  special  muscle 
ferment. 

(3)  Co/oMnre$r  wato-,  either  haemoglobin  or  myo-heematin.  (Seep.  138.) 
The  colouring  matter  is  said  to  exist  in  the  isotropous  portion  of  the  fibre. 

(4)  Various  nitrogenous  matters,  all  of  which  have  been  discovered  in 
extract  of  meat,  namely,  lecithin,  creatin,  creatinin,  xanthin,  hypo- 
xanthin,  taurin,  urea,  and  inosinic  and  uric  acids. 

When  muscular  fibre  is  allowed  to  macerate  iu  cold  water,  the  water 
becomes  red,  and  it  dissolves  some  of  the  constituents  of  muscle.  If  such  an 
extract  is  boiled,  all  soluble  proteids  are  coagulated,  and  if  the  fluid  is  then 
filtered,  a  liquid  is  obtained  holding  in  solution  the  non-nitrogenous  matters  and 
also  the  soluble  nitrogenous  matters  above  enumerated.  A  watery  extract  thus 
freed  from  proteids,  and  then  evaporated  till  a  thick  viscid  mass  is  obtained,  is 
extract  of  meat.  The  following  are  the  average  percentage  amounts  of  some  of 
the  nitrogenous  substances  obtained  from  muscle  : — Creatin,  in  frog's  muscle, 
•263;  carnin,  in  Liebig's  extract,  1-00;  uric  acid  (Haycraft),  -01  ;  and  urea,  in  rab- 
bit's muscles  (Picard),  3 '00  (?).  Traces  of  creatinin,  sarcin,  xanthin,  inosinic  acid, 
and  taurin  have  also  been  detected,  but  no  statement  can  be  made  as  to  the  quan- 
tity usually  present. 


362 


THE  CONTRACTILE  TISSUES. 


(5)  ^'arious  non-nitrogenous  matters,  such  as  fats,  the  two  lactic  acids 
(ethylidene-lactic  acid  or  para-  or  sarco-lactic  acid  and  ethylene-lactic 
acid),  inosite  or  muscle  sugar,  glycogen  or  animal  starch,  dextrin,  and 
glucose.  The  amount  of  glycogen  has  been  found  to  vary  from  •43  per 
cent,  in  the  muscles  of  a  frog  to  from  -47  to  -95  in  those  of  a  rabbit. 
Inosite  has  been  found  only  to  the  small  amount  of  -003  per  cent. 
Small  c^uantities  of  volatile  acids,  such  as  formic,  acetic,  and  butyric 
acids,  have  also  been  found.  In  dead  muscle,  or  in  muscle  which  has 
been  excited  to  frec^uent  contractions  in  short  intervals  of  time,  lactic 
acid,  or  the  variety  called  para-  or  sarco-lactic  acid,  has  always  been 
found.  It  has  been  supposed  to  originate  from  the  sugar  or  glycogen 
present  in  the  muscle. 

(6)  The  principal  salts  are  the  phosphates  of  the  alkalies  and  alkaline 
earths,  chloride  of  jDotassium,  and  a  small  quantit}'  of  chloride  of  sodium 
and  of  sulphates  of  the  alkalies.  The  ash  of  muscle  amovuits  to  1  or 
1-5  per  cent,  of  the  total  weight. 

(7)  JVater,  to  the  extent  of  from  74  to  80  per  cent. 

(8)  The  follo^\ang  gases  have  been  separated  from  100  parts  of  muscle 
— Carbonic  acid,  14-40;  nitrogen,  4-90;  and  oxygen,  -09— total,  19-39. 
It  is  probable  that  much  of  the  carbonic  acid  may  have  arisen  from 
decomposition. 

Von  Bibra  gives  the  following  rough  quantitative  analysis  of  muscle  from 
different  species  of  animals  in  1000  parts — 


Man. 

Ox. 

Bird. 

Fish. 

Frog. 

Water, 

745-5 

776-0 

717-6 

797-8 

804-3 

Solids, 

255-5 

224-0 

282-4 

202-2 

195-7 

Albumin,    • 

19-3 

19-9 

26-8 

23-5 

18-6 

Gelatinous  matter, 

20-7 

19-8 

12-3 

19-8 

24-8 

Alcoholic  extract, 

37-1 

30-0 

41-2 

34-7 

34-6 

Fat,    -         -         -         . 

23-0 

— 

25-3 

111 

1-0 

Vessels,  etc., 

155-4 

154-3 

176-8 

113-1 

116-7 

Fresh  beef,  on  calcination,  has  yielded  1  -46  to  1  -63  per  cent,  of  ash,  in  100  parts 
of  which  there  are  35-94  of  potassium,  traces  of  sodium,  3-31  of  magnesium,  1-73 
of  calcium,  4-86  of  chlorine,  '98  of  iron,  34-36  of  phosphoric  acid,  3-37  of 
sulphuric  acid,  2  07  of  silicic  acid,  and  8-02  of  carbonic  acid. 

Glycogen  or  animal  starch  abounds  in  the  muscles  of  the  embryo  and 
of  the  foetus,  and  the  muscles  of  yotmg  animals  contain  more  water  than 
those  of  animals  advanced  in  age.  The  amount  of  fat  also  increases 
■with  age. 

Living  muscle  in  a  state  of  rest,  as  already  mentioned,  is  slightly 
alkaline  from  containing  phosphate  of  potash,  K2IIPO4.     After  a  period 


CHEMICAL  CONSTITUTION  OF  MUSCULAR  FIBRE.        363 

of  activity  it  becomes  acid,  partly  by  the  formation  of  free  lactic  acid 
from  carbo-bydrates,  and,  according  to  some  authorities,  partly  from  the 
presence  of  the  acid  phosphate  of  potash,  KH2PO4. 

Chap.  III.— ELECTEICAL  APPARATUS  EMPLOYED   IN  THE  STUDY 

OF  MUSCLE. 

In  studying  the  phenomena  of  muscular  contraction,  we  require  to 
stimulate  the  living  muscle  or  the  nerve  supplying  it.  The  agent  most 
commonly  employed  as  a  stimulus,  because  it  is  the  most  effective  and 
the  most  convenient,  is  electricity.  This  agent  may  be  obtained  by 
various  appliances,  and  it  may  be  employed  in  different  ways.  The 
student  should,  at  this  stage,  acquire  a  practical  acquaintance  with 
some  of  these  methods,  so  that  he  may  be  able  to  use  electrical 
apparatus  intelligently,  both  in  the  study  of  physiology  and  in  the 
treatment  of  disease. 

I.  General  Statement  and  Definitions. 

When  a  body  is  electrified  or  charged  mth  electricity  the  measure 
of  its  electrification  is  called  its  electrical  potential.  Thus,  if  a  plate  of 
metal  such  as  zinc  or  copper  is  immersed  in  a  solution  of  sulphuric 
acid,  there  is  a  difference  of  electrical  potential  between  the  metal  and 
the  liquid.  This  difference  of  potential  is  not  the  same  for  zinc  as  it  is 
for  copper,  and  hence  when  a  plate  of  zinc  and  a  plate  of  copper  are 
both  immersed  in  the  same  liquid,  mthout  touching  each  other,  there 
is  a  difference  of  potential  between  the  copper  and  the  zinc.  Again, 
when  a  piece  of  zinc  is  in  contact  with  a  piece  of  copper,  there  is  a 
difference  of  potential  between  the  zinc  and  the  copper.  If,  now,  we 
suppose  the  plates  immersed  in  the 
liquid  to  be  put  in  contact  outside 
by  a  wire,  say  of  copper,  as  in  Fig. 
214,  there  >vill  be  a  difference  of 
potential  between  the  zinc  and  the 
liquid,  then  a  smaller  difference  of 
opposite  sign  between  the  liquid 
and  the  copper,  and  finally  a  dif- 
ference between  the  copper  and  the 
zinc.  The  algebraic  sum  of  these 
differences  is  not  zero,  and  there 
results,  in  consequence  of  the  ten- 
dency  of  electricity  to   flow   from 

■'  .  "^       .  Fig.  214. — Diagram  of  a  Voltaic  Element. 

points   of  high   to   points    of    low 

potential,  a  current  of  electricity  which,  by  a  common  convention,  is 


364  THE  CONTRACTILE  TISSUES. 

said  to  How  from  the  copper  to  the  zinc  throixgh  the  external  circuit  or 
■wire  M,  and  from  zinc  to  copper  through  the  liquid.  This  flow  of 
electricity  would  reduce  the  Avhole  circuit  to  the  same  potential  were  it 
not  for  the  fact  that  the  passage  of  electricit}^  through  the  liquid  de- 
composes it,  and  l^y  so  doing  generates  electricity,  which  serves  to  keep 
the  current  flowing.  The  energ}'^  required  to  keep  the  current  flowing 
through  the  circuit  is  supplied  by  the  chemical  action,  the  result  of 
which  is  the  production  of  sidphate  of  zinc  at  the  expense  of  the  zinc 
plate  and  the  liberation  of  a  corresponding  amount  of  hydrogen  from 
the  sulphuric  acid  (H^SO^  +  Zn  =  ZnSO^  +  H.,).  The  hydrogen  is  set  free 
at  the  copper  plate.  The  arrangement  just  described  is  called  a  roltaic 
clement;  the  copper  and  zinc  plates  being  commonly  termed  the  plates, 
and  the  liquid  the  electrolyte.  The  copper  plate  is  called  the  positive 
pole,  and  the  zinc  plate  the  negative  pole,  and  the  Avires  forming  the 
external  circuit,  or  joining  the  two  poles  of  the  cell  to  any  piece  of 
apparatus,  are  called  the  electrodes. 

The  algebraic  sum  of  the  contact  differences  of  potential  above  re- 
ferred to  is  called  the  potential  of  the  cell,  but  Avhen  the  circuit  is  closed 
and  a  current  caused  to  floAv,  it  is  more  commonly  called  the  electro- 
motive force  (e.  m.  f.)  of  the  circuit,  i.e.  the  electrical  force  or 
pressure  which  causes  the  current  to  flow.  The  electromotive  force 
in  the  circuit  of  a  voltaic  cell  producing  a  cvuTent  is  the  same  as  the 
<lifl'erence  of  potential  betAveen  the  plates  Avhen  no  current  is  floAving. 
It  is  not  the  same  as  the  diff'erence  of  potential  betAveen  the  poles  of 
the  cell  Avhen  the  current  is  floAving,  in  consequence  of  another  pro- 
Ijerty  of  the  solids  and  liquid  forming  the  circuit,  namely,  their  electrical 
resistance,  ^^^len,  for  example,  a  current  of  electricity  is  made  to  floAV 
throixgh  a  Avire,  it  is  found  that,  AA^th  the  same  difference  of  potential 
betAveen  the  ends  of  the  AA^re,  the  strength  of  the  current  is  inversely 
as  the  length  of  the  Avire,  and  directly  as  its  cross  section.  Thus,  the 
same  e.  m.  f.  Anil  cause  a  stronger  current  to  floAv  in  a  thick  A\are  than 
in  a  thin  one  of  the  same  length,  or  in  a  short  Avire  than  in  a  long  one 
of  the  same  thickness.  This  property  Avhich  the  Avire  possesses  of 
opposing  the  electric  current  is  called  its  electrical  resistance.  In  Adrtue 
of  this  resisting  property,  AA'hich  is  possessed  in  a  greater  or  less  degree 
by  all  substances,  a  certain  e.  m.  f.  (a)  is  required  to  cause  the  current  to 
floAv  through  each  part  of  the  circuit  of  the  cell,  and  hence  only  a  part 
(b)  is  available  for  the  external  AAare  circuit.  This  part  (a)  is  greater  and 
greater  the  longer  and  thinner  the  Avire,  M,  and  it  is  equal  to  the  whole 
potential  of  the  cell  AA'hen  the  resistance  of  the  external  part  is  in- 
finitely great  compared  Avith  that  of  the  liquid,  that  is,  AA^hen  no 
current  is  floAving. 


APPARATUS  EMPLOYED  IN  STUDY  OF  MUSCLE.        365 

The  relation  between  the  current  strength,  C,  the  e.  m.  f.,  E,  and 
the  resistance,  R,  was  first  correctly  given  by  Ohm,  and  is  kno^^ai  as 
Ohm's  law.     Algebraically,  it  may  be  put 

E 

As  stated  above,  the  resistance  of  any  conductor  is  directly  proportional 
to  its  length,  /,  and  inversely  proportional  to  the  area  of  its  cross 
section,  a.  If  we  call  the  specific  resistance  S,  that  is  the  resistance  of  unit 
length  of  a  %vire  of  the  conductor,  the  cross  sectional  area  of  which  is 
unity,  we  may  write 

H  =     • 

a 

A  battery  is  an  arrangement  or  apparatus  for  producing  electricity. 
In  its  sim,plest  form  it  is  a  cell  or  element ;  several  elements  constitute  a 
battery.  Elements  are  put  up  in  series  or  for  tension  when  the  positive 
of  the  first  is  united  to  the  negative  of  the  second,  and  the  positive  of 
the  second  to  the  negative  of  the  third,  and  so  on,  as  shown  in  Fig.  215. 


Fig.  215. — Battery  of  four  elements  united  in  series. 

On  the  other  hand,  elements  are  imited  for  quantity  or  surface  when  all 
the  positive  poles  are  joined  together  and  all  the  negative  poles  are  also 
joined. 

The  e.  m.  f.  of  a  battery  depends  on  the  kind  of  chemical  operations 
occurring  in  it,  and  to  a  small  extent  on  the  temperature  at  which  they 
occur.  A  battery  has  always  a  certain  amount  of  internal  resistance,  I, 
depending  on  its  size  and  form  and  the  lic[uids  used.  If  we  increase  the 
size  of  the  plates  and  bring  them  close  together,  the  resistance  is  dimin- 
ished. The  e.  m.  f  of  a  battery  and  its  internal  resistance,  r,  are  its 
constants.  It  is  important  to  notice  (a)  that  n  elements  in  series  behave 
like  one  element,  of  which  the  e.  m..  f.  =  n  e,  and  the  internal  resistance  = 
n  b ;  and  (6)  that  n  elements,  put  up  parallel  or  for  quantity,  act  like 
one  single  element  of  the  same  electromotive  force,  e,  and  of  which  the 

internal  resistance  =  l 


3tJ6  THE  CONTRACTILE  TISSUES. 

If  a  1)attery  becomes  ^veak,  this  is  due  to  polarization,  caused  by  an 
accumulation  of  hydrogen  or  other  su])stance  that  may  be  deposited  on 
the  positive  plate.  This  not  only  increases  the  resistance  but  also  pro- 
duces an  electromotive  force  opposing  the  electromotive  force  of  the  cell, 
and  thus  ])olarization  diminishes  the  e.  m.  f.  of  the  cell.  Many  of  the 
arrangements  in  different  elements  are  intended  to  remove  the  hydrogen 
or  other  film  and  thus  get  rid  of  polarization. 

If  r  be  put  for  the  external  resistance  of  a  galvanic  circuit,  then  the 
total  resistance  E  in  the  circuit  will  be  r  +  n  h,  and  the  total  e.  m.  f 
11  e  =  E.     Hence  the  current  flowing  would,  by  Ohm's  law,  be 

C  =     "^ 
r  +  nb' 

XoAV  it  is  clear  from  this  equation  that  if  h  be  at  all  high  compared 
\nth.  r,  very  little  advantage  Avill  be  gained  by  using  a  large  number  of 
cells  in  series.  Let  us  consider  what  would  be  the  effect  of  grouping 
the  n  cells,  j^artly  in  series  and  partly  in  parallel.  Divide  the  n  cells 
into  X  groups  and  suppose  the  n/x  cells  of  each  group  to  be  put  in  series, 
and  the  x  groups  to  be  put  in  parallel.  The  e.  m.  f  of  each  group,  and 
therefore  of  the  battery,  would  be  ~e,  and  the  internal  resistance-/;. 

X  X 

71/ 

The  total  resistance  of  x  groups  in  parallel  would  be  ^b/x  or  nh/x^.     The 
current  flowing  would  then  be 


r  +  nb  /x^        rx  +  nb/x' 
The  right  hand  side  of  this  equation  may  be  written 


+ 


^Vv  -  (v^^  -  4y 


Now  this  quantity,  and  therefore  C,  is  clearly  greatest  when  the  second 
term  of  the  denominator  is  zero,  as  the  first  term  is  constant.  Hence 
the  best  result  will  be  obtained  when  the  cells  are  so  arranged  that 

r  X        b  ,  o         nb 

—    =  -,  or  when  a;-  =    — . 
n  X  r 

This  gives  the  proper  number  to  take  for  x,  and  although  it  may  not  be 
always  possible  to  divide  the  number  of  cells  in  the  battery  by  this 
number,  the  nearest  number  to  x  which  will  divide  n  without  a  re- 
mainder should  be  taken.     It  is  interesting  to  notice  that  the  equation 

„        nb 
X'   =    — , 
r 

may  be  wiitten 

71  b 
r  =   ■ — , 

which  shows  that  when  the  battery  is  arranged  for  best  effect  the  in- 
ternal resistance  of  the  battery  is  equal  to  the  external  resistance  in  the 


APPARATUS  EMPLOYED  IN  STUDY  OF  MUSCLE.        367 

circuit.  It  must  be  kept  in  mind,  however,  that  there  is  no  advantage 
but  a  disadvantage  in  increasing  the  resistance  of  a  given  battery  in 
order  to  make  it  equal  to  the  external  resistance.  This  rule  can  only 
be  applied  to  such  large  batteries  of  high  resistance  cells  that  the  resist- 
ance of  the  cells  in  series  is  great  compared  -with  the  external  resistance. 
An  example  may  make  the  meaning  of  the  above  investigation  clearer. 
Suppose  we  have  a  battery  of  20  cells,  the  internal  resistance  of  each  of 
which  is  1  ohm,  and  wish  to  pass  as  strong  a  current  as  possible  through 
a  resistance  of  5  ohms.  We  have  here  n=20,  h-\,  and  r  =  5,  and 
hence — 

„     n6      20x1       .  „ 

a;^=  —  = =4,   ox  X  =  2, 

r  o 

That  is  to  say,  the  best  result  will  be  obtained  by  dividing  the  battery 
into  two  batteries  of  10  cells  each,  and  joining  these  two  batteries 
parallel  to  each  other — the  terminal  zinc  of  the  one  to  the  terminal 
zinc  of  the  other,  and  the  terminal  copper  of  the  one  to  the  terminal 
copper  of  the  other.  The  resulting  battery  is  then  equivalent  to  a 
battery  of  10  cells,  each  having  an  internal  resistance  of  half  an  ohm. 
The  number  of  cells  in  the  battery  is  thus  halved,  and  the  internal 
resistance  of  each  cell  is  also  halved,  so  that  the  total  resistance  of  the 
battery  is  only  one  quarter  of  what  it  would  be  if  the  20  cells  were 
joined  in  series,  while  the  e.  m.  f.  is  half  what  it  would  be  in  that  case. 
This  is  an  advantage  in  the  case  supposed,  because  the  external  resist- 
ance is  only  5  ohms,  while  the  internal  resistance  of  the  20  cells  in 
series  would  be  20  ohms.     The  current  through  the  resistance,  with  all 

the  cells  in  series,  would  be  c  =  ;' ^^  or  -e,  and  the  currents  through 

25  5 

the  resistance,  "with  the  battery  arranged  as  10  double  cells,  would  be 

c  =  —  or  e,  that  is,  one  fifth  strons;er.     Had  there  been  30  cells  in  the 
10         '  '  * 

battery,  it  might  have  been  arranged  either  as  10  triple  cells  or  as  15 

double    cells   with    about    equal    advantage,   because,    in    this    case, 

x^  =  —  =  6  or  a;  =  ^6,  which  is  about  equally  distant  from  2  and  from 
5 

3,  but  slightly  nearer  2.     The  next  number  of  cells,  which  gives  an 

exact  integer  for  x  when  5=1  and  r  =  5,  is  45,  which  gives  a;^  =  9  or  a;  =  3. 

Hence,  for  such  a  case,  it  would  be  best  to  arrange  the  45  cells  as  15 

triple  cells,  and  so  on  for  other  cases. 

Electrical  Measurements. 

The  system  of  electrical  measurements  now  in  use  is  founded  on  the  centimetre 
as  the  unit  of  length,  the  gramme  as  the  unit  of  mass,  and  the  mean  solar  second 


368  THE  CONTRACTILE  TISSUES. 

as  the  uuit  of  time.  This  system  is  commonly  referred  to  as  the  C.  G.  S.  system. 
The  electromagnetic  units  need  only  be  referred  to  in  this  work ;  they  are  based 
on  the  forces  exerted  between  two  magnetic  poles.  Beginning  with  the  unit  of 
force  or  the  dyne,  which  has  already  been  defined  (p.  10),  the  following  description 
will  indicate  the  relation  between  the  difierent  units — 

1.  Unit  Quantity  of  Ma(j>iet{sm,  or  the  unit  magnetic  pole,  is  that  quantity  of 
magnetism  which,  when  placed  at  a  distance  of  one  centimetre  from  an  equal 
quantity  of  magnetism,  repels  it  with  the  force  of  one  dyne. 

2.  U7iit  Magnetic  Field  is  such  a  magnetic  field  that  when  unit  quantity  of 
magnetism  is  placed  in  it,  it  is  acted  on  by  a  force  of  one  dyne.  The  unit  magnetic 
field  is  thus  the  field  produced  by  unit  quantity  of  magnetism  at  a  distance  of  one 
centimetre. 

3.  Unit  current  of  electricity  is  such  a  current  that  when  made  to  flow  round  a 
circle  of  one  centimetre  radius,  it  produces  a  magnetic  field  of  as  many  units 
intensity  at  the  centre  of  the  circle  as  there  are  centimetres  in  the  length  of  the 
circumference  of  the  circle.  The  unit  current  flowing  in  a  circle  of  one  centi- 
metre radius  would  therefore  act  on  unit  quantity  of  magnetism  placed  at  the 
centre  of  the  circle  with  a  force  of  2ir  dynes. 

4.  Unit  quantity  of  electricity  is  the  quantity  conveyed  by  i;nit  current  in  one 
second. 

5.  Unit  difference  of  potential  is  the  diflference  of  potential  between  the  ends  of 
a  conductor  of  one  centimetre  length,  when  it  is  held  with  its  length  at  right  angles 
to  the  direction  of  magnetic  force  in  a  magnetic  field,  and  kept  moving  uniformly 
with  a  velocity  of  one  centimetre  per  second  in  a  direction  at  right  angles  to  its 
own  length  and  the  direction  of  the  magnetic  force  in  the  field. 

6.  Unit  electromotive  force  is  produced  in  a  closed  circuit,  if  one  centimetre  of  its 
length  is  held  in  the  manner  and  moved  in  the  dii'ection  and  with  the  velocity 
described  in  the  last  definition. 

7.  Unit  resiatance  is  the  resistance  which,  when  cted  on  by  unit  electromotive 
force,  allows  unit  current  to  flow. 

8.  Unit  capacity  is  the  capacity  of  a  body  which  requires  unit  quantity  of  elec- 
tricity to  raise  its  potential  by  units. 

In  practice,  the  magnitudes  of  the  units  above  defined  were  found  inconvenient 
and  certain  multiples  and  sub-multiples  have  been  adopted.  The  units  of  any  im- 
portance for  physiological  purposes  are  the  unit  of  current,  the  Ampere ;  the  unit 
quantity  of  electricity,  the  Coulomb ;  the  unit  electromotive  force,  the  Volt ;  the 
unit  resistance,  the  Ohm  ;  and  the  unit  capacity,  the  Farad  or  Microfarad. 

The  Ampere  is  equal  to  one  tenth  of  the  c.  g.  s.  unit  of  current,  or  approxi- 
mately the  current  of  an  ordinary  Daniell  through  an  Ohm  ;  the  Coulomb  to  one 
tenth  the  c.  g.  s.  unit  of  quantity,  or  the  quantity  of  electricity  conveyed  by  an 
Ampere  in  one  second  ;  the  Volt  to  100,000,000  times  the  c.  g.  s.  unit  of  e.  m.  f., 
or  approximately  the  e.  m.  f.  of  a  Daniell's  cell  ;  the  Ohm  to  1,000,000,000  times 
the  c.  g.  s.  unit  of  resistance,  or  the  resistance  of  a  column  of  pure  mercury  at 
0°  C.  1  mm.  square  and  1,050  mm.  in  length;  the  Farad  to  tuoOu^ouuo  ^^  ^^^ 
c.  g.  s.  unit  of  capacity  ;  and  the  Microfarad,  which  is  the  common  practical  unit, 
is  the  millionth  part  of  a  Farad.  ^ 

^  The  terms  Ampere,  Coulomb,  Volt,  etc.,  are  often  written  without  use  of 
capital  letters,  thus  ampere,  coulomb,  volt,  etc. 


APPARATUS  EMPLOYED  IN  STUDY  OF  MUSCLE.        369 


2.  Voltaic  Elements. 

Many  varieties  of  voltaic  elements  may  be  employed  for  physiological  purposes. 
The  following  are  the  most  common — 


Fig.  216.— Daniell's  Element. 


(1)  Daniell.  There  are  various  forms  of  this  convenient  element.  The  one 
shown  in  Fig.  216  consists  of  a  glass  jar  containing  a  solution  of  sulphuric  acid,  1 
to  7  of  water  ;  in  this  is  placed  a  roll  of  amalgamated  zinc,  Z  ;  within  the  roll  there 
is  a  porous  earthenware  jar  containing  a  rolled  piece  of  copper,  C,  immersed  in  a 
saturated  solution  of  sulphate  of  copper.  Sulphate  of  zinc  is  formed  by  the  action 
of  the  sulphuric  acid  on  the  zinc  and  hydrogen  is  set  free.  The  hydrogen  passing 
through  the  porous  vessel  reduces  part  of  the  sulphate  of  copper,  depositing  copper 
on  the  copper  plate,  and  the  sulphuric  acid  thus  liberated  passes  into  the  solution 
of  the  acid  in  the  outer  jar,  and  thus  makes  up  for  the  loss  of  the  acid  caused  by 
the  continuous  formation  of  sulphate  of  zinc.  Thus,  the  current  is  very  constant 
so  long  as  an  ample  supply  of  crystals  of  sulphate  of  copper  is  placed  in  the  inner 
compartment  and  so  long  as  the  zinc  plate  in  the  outer  vessel  lasts.  The  e.  m.  f .  is 
=  1'072  volt.  The  positive  electrode  is  connected  with  the  copper  and  the 
negative  electrode  with  the  zinc.  This  element  is  useful  when  it  is  desirable  to 
have  a  tolerably  constant  current. 

(2)  Bunsen.  This  element  consists  of  a  vessel  containing  dilute  sulphuric  acid, 
1  to  7  of  water,  in  which  is  a  roll  of  amalgamated  zinc  ;  in  this  is  a  porous  earthen- 
ware vessel  containing  a  rectangular  block  of  carbon  in  strong  fuming  nitric  acid 
(Fig.  217).  The  hydrogen  set  free  in  the  outer  compartment  by  the  action  of  the 
sulphuric  acid  on  the  zinc  is  absorbed  by  the  nitric  acid,  and  thus  polarization  is  to 
a  large  extent  prevented.      Its  e.  m.  f.  is  1  -9  volt.      The  positive  electrode  is  con- 

I  2A 


370 


THE  CONTRACTILE  TISSUES. 


nectecl  with  the  carbon  and  the  negative  with  the  zinc.  This  element  is  incon- 
venient for  ordinary  physiological  purposes  on  account  of  the  acid  fumes  given  off 
when  it  is  in  action. 

(3)  Grove,     This  element,  of  which  a  small  and  convenient  form  is  shown  in  Fig. 
218,  is  similar  to  Bunsen's  element,  except  that  a  strip  of  platinum,?,  takes  the  place 


Fig.  217. — Bunsen's  Element. 


of  the  carbon  in  the  fuming  nitric  acid.  Its  e.  m.  f.  is  1  '96  volt.  The  positive 
electrode,  K,  is  connected  -vnth.  the  platinum  and  the  negative  electrode  with  the 
zinc,  Z. 


Fig.  21S.— Grove's  Element. 


(4)  LeclancM.     This  element,  of  which  there  are  various  forms,  consists  of  a 
glass  vessel  or  jar,  containing  a  saturated  solution  of  sal-ammoniac  in  water,  in 


APPARATUS  EMPLOYED  IN  STUDY  OF  MUSCLE. 


371 


which  is  immersed  a  roll  of  amalgamated  zinc,  Z  (Fig.  219).  In  this  is  placed  a  jar 
T,  containing  a  plate  of  carbon,  K,  surrounded  with  small  pieces  of  carbon  mixed 
with  black  oxide  of  manganese.  Its  e.  m.  f .  is  1  '48  volt.  The  positive  electrode,  B, 
is  connected  with  the  carbon  and  the  negative  electrode  with  the  zinc,  C  The 
Leclanche  is  a  very  convenient  element,  united  in  series,  for  medical  purposes. 

(5)  Gaiffe.  This  is  a  small  and  convenient  form  of  element  much  used  in  the 
■construction  of  batteries  employed  by  physicians.  It  consists  of  zinc  (not 
amalgamated)  in  a  5  per  cent,  solution  of  chloride  of  zinc,  and  of  silver  surrounded 


Fig.  219. — Leclanche's  Element. 


by  chloride  of  silver.     Its  e.  m.  f .  =  1  •02  volt.     The  positive  electrode  is  connected 
with  the  silver  and  the  negative  electrode  with  the  zinc. 

(6)  Sniee.  Smee's  element  consists  of  two  plates  of  amalgamated  zinc,  having  a 
plate  of  platinized  silver  between  them,  the  whole  being  immersed  in  a  solution  of 
sulphuric  acid,  1  to  7  of  water.  The  positive  electrode  is  connected  with  the 
platinized  silver  and  the  negative  electrode  with  the  zinc.  The  e.  m.  f.  is  "4" 
volt. 

(7)  Marie-Davy.  This  is  an  element  much  used  in  the  construction  of  medical 
batteries.  It  consists  of  amalgamated  zinc  in  slightly  acidulated  water  and  of  car- 
bon in  a  paste  of  mercurous  sulphate.  Its  e.  m.  f .  is  1  '52  volt.  The  positive 
electrode  is  connected  with  the  carbon  and  the  negative  electrode  with  the 
zinc. 


372 


THE  CONTRACTILE  TISSUES. 


(8)  Grtnet  or  Bichromate.     This  is  an  element  of  great  convenience.    It  is  formed 
of  one  plate  of  amalgamated  zinc  placed  between  two  plates  of  carbon,  and  the 

whole  is  immersed  in  a  fluid  having  the 
following  composition— Water,  100  parts  ; 
snlphurio  acid,  25  parts  ;  and  bichromate  of 
potash,  10  parts.  The  zinc  plate  attached 
to  the  rod,  B,  may  be  pulled  up  out  of  the 
fluid  when  the  element  is  not  required,  so 
that  the  fluid  does  not  require  to  be  changed 
frequently.  Immeiliately  after  changing 
with  fresh  fluid  this  element  may  give  an 
e.  m.  f.  of  2"03  volts  for  a  few  seconds,  but  it 
rapidly  becomes  weaker,  and  falls  to  about 
1  "8  volt.  The  positive  electrode,  E,  is  con- 
nected with  the  carbon  and  the  negative 
electrode  with  the  zinc,  D  (Fig.  220). 

(9)  No(i-Ddrffel  Thermo- Electric  Battery 
or  Pile.  This  consists  of  a  number  of 
thermo-electric  junctions  concentrically  ar- 
ranged. One  of  the  metals  is  German  silver, 
the  other  is  an  alloy  of  antimony  and  zinc, 
bhe  exact  composition  of  which  is  known 
only  to  the  manufacturers  of  the  element. 
One  of  [the  metals  of  each  junction  is  ex- 
panded to  form  a  cylinder,  so  as  to  secure 
a  uniform  temperature  at  one  junction.  The 
other  junction  is  heated  by  placing  the  apparatus  over  the  flame  of  a  spirit  lamp. 

The  elements  are  arranged  in 
series  to  form  a  batteiy,  as- 
shown  in  the  figure.  Each 
element  has  an  e.  m.  f.  of  ^V 
volt,  and  a  battery  of  20 
elements  has  therefore  an 
e.  m.  f.  of  1"25  volt.  It  is 
remarkable  that  such  an  ar- 
rangement transforms  into- 
electricity  less  than  one  per 
cent,  of  the  heat  energy  given 
out  by  the  source  of  the  heat 
used  in  generating  the  current. 
For  physiological  purposes 
this  thermo-electric  battery 
is  very  convenient,  as  it  is 
readily  put  in  working  order 
and  there  is  no  risk  of  injury 
to  sensitive  structures  like 
nerves  from  acid  fumes  (Fig. 
221).  The  positive  electrode- 
Fig.  221.-Noe-DorffelThermo-Electric  Battery.  .^    connected  with   the  alloy 

of  the  antimony  and  zinc,  and  the  negative  with  the  German  silver. 


Fig.  220.— Grenet's  Element. 


APPARATUS  EMPLOYED  IN  STUDY  OF  MUSCLE.         873 

(10)  Storage  Cell.  If  there  is  a  dynamo  machine  available,  the  physiologist  may 
abandon  the  use  of  all  kinds  of  batteries  (except,  perhaps,  a  Grenet  and  a  Noe- 
Dcirffel  thermal  pile)  and  employ  a  small  accumulator,  which  may  be  charged 
from  time  to  time.^ 

The  late  Professor  Fleeming  Jenkin  thus  summarized  the  probable  sources  of 
weakness  in  a  battery — "  When  a  battery  does  not  give  the  expected  results,  one 
•of  the  following  defects  is  to  be  looked  for  :  (1)  Exhausted  solutions — for  example, 
in  a  Daniell  battery,  the  sulphate  of  copper  worked  out,  leaving  the  solution 
colourless,  or  nearly  so ;  (2)  bad  contacts  between  the  electrodes  and  the  wires, 
•oxidized  or  badly  screwed-up  binding  screws,  etc.  ;  (3)  empty  or  partially  empty 
cells  ;  (4)  filaments  of  metallic  deposit  causing  short  circuiting  between  the 
battery  plates  ;  (5)  creeping  or  deposits  of  salts  forming  short  circuits  either 
between  the  plates  or  from  cell  to  cell.  Shaking  the  cells  increases  their  e.  ni.  f. 
temporarily  by  disengaging  the  gases  adherent  to  the  plates.  Floating  filaments 
and  broken  plates  give  rise  to  false  contacts,  which  cause  the  current  given  by  a 
battery  to  vary  suddenly  when  it  is  shaken. " 


3.  Induction  Coils. 

The  form  of  induction  coil  most  commonly  employed  by  physiologists 
is  the  sledge  indudorium  of  Du  Bois-Eeymond,  seen  in  Fig.  222,  pro- 
vided with  Neefs  Interruptor,  represented  diagrammatically  in  Fig.  223. 


^■^'U'en.-^^i 


Fig.  222. — liiductorium  of  Du  Buis-Reymond  :  o,  primary  coil ;  b,  secondary  coil ; 
c,  bunch  of  wires  in  centre  of  primary  coil,  for  increasing  intensity  of  induction 
current ;  d,  binding  screw,  for  attachment  of  wire  from  galvanic  element.  The 
current  passes  up  the  pillar  d,  along  steel  spring  to  e,  from  there  to  the 
screw  the  point  of  which  touches  the  back  of  the  spring  at  e.  Frora  / 
through  wire  of  primary  coil  to  i,  along  the  two  pillars  of  soft  iron  i,  which  it 
renders  magnetic  and  thus  draws  down  the  head  of  the  spring  k.  This  interrupts 
the  current  at  e,  by  breaking  the  contact  of  the  spring  with  the  screw  point. 
When  the  current  is  thus  interrupted,  the  spring  flies  up  by  its  elasticity  and 
again  establishes  the  circuit  at  e.  Thus  the  current  is  opened  and  closed  automa- 
tically, and  each  time  it  is  opened  and  closed  there  is  an  induction  shock  from 
the  secondary  coil  6.  The  intensity  of  the  induced  current  becomes  weaker  as 
■we  withdraw  b  from  a  along  the  graduated  board  o.  The  automatic  apparatus 
was  applied  by  Neef.  The  binding  screw  a  is  connected  by  a  wire  to  /" ;  the  bind- 
ing screw  h  by  a  wire  to  i.  When  the  wires  from  the  battery  are  connected  with  g 
and  h,  Neefs  arrangement  is  out  of  the  circuit,  and  an  opening  or  closing  shock 
may  then  be  obtained  by  opening  or  closing  a  key  (Fig.  224)  interposed  in  the 
circuit.     The  interrupter  was  originally  invented  by  Philipp  Wagner, 

^  As  to  the  structure  and  uses  of  accumulators,  see  Hospitaller's  Electricians' 
Pocket  Book,  p.  210. 


:37-i 


THE  CONTRACTILE  TISSUES. 


The  descriptions  appended  to  the  figures  explain  the  mechanism  of  the 
instrument.  Neef  s  interruptor  woi^ks  automatically,  and  thus  a  rapid 
series  of  shocks  is  transmitted  to  the  nerve  or  muscle. 


Fig.  223. — Diagi-ammatic  view  of  the  arrangement  of  Neef's 
interruptor  at  the  end  of  the  indnctoriuni,  seen  in  Fig.  222.  The 
arrows  indicate  the  direction  of  the  current.  A,  wire  connected 
with  the  +  pole  of  battery  ;  and  IJ,  with  the  -  pole,  c,  primary- 
coil  ;  and  i,  secondary  coil. 

The  secondary  current  induced  in  the  secondary  coil  at  the  moment  of  opening 
is  in  the  same  direction  as  that  of  the  primary,  while  that  of  closing  is  in  the  op- 
posite direction.  Thus,  the  direction  of  the  currents  in  the  secondary  is  reversed 
with  each  momentary  opening  and  closing  of  the  primary,  "With  such  an  arrange- 
ment, it  is  found  that  the  opening  shock  acts  more  powerfully  than  the  closing 
shock.  This  is  due  to  the  fact  that,  at  the  moment  of  the  closing  shock,  an  extra 
current  is  induced  in  the  primary  coil  by  the  action  of  each  coil  of  wire  on  all  the 
other  coils.  The  extra  current  so  induced  in  the  primary,  being  in  the  opposite 
direction  to  the  chief  ci;rrent  in  the  primary,  weakens  the  latter,  so  that  the 
induced  current  occurring  in  the  secondary  coil  at  the  moment  of  dosing  the 
primary  is  thus  weakened.  When  the  circuit  of  the  primary  coil  is,  on  the  other- 
hand,  opened,  no  extra  current  occurs  in  the  primary,  and  its  effect  on  the 
secondary  coil  is  therefore  greater,  because  the  primary  current  at  the  moment  of 
CLOSING  OPENING  Opening  has  not  been  weakened.     Thus, 

the  opening  shock  is  considerably  stronger 
than  the  closing  shock. 

The  relation  of  the  opening  and  closing- 
shocks  is  clearly  shown  by  the  diagram 
in  Fig.  224,  in  which  I  refers  to  the  cur- 
rent in  the  primary,  and  II  to  the  current 
in  the  secondary  coil,  and  A  A  is  the 
basement  line  of  the  upper,  and  h  b  the 
basement  line  of  the  lower  cui-ves.  On 
closing  the  primary  circuit,  the  current 
in  the  primary  coil  in  place  of  rising  to 
its  maximum,  indicated  by  the  dotted  vertical  line  A  B,  attains  this  maximum 
slowly  as  shown  by  the  curved  line  1 .     This  is  owing  to  the  production  of  the 


Fio.  22-1. — Diagram  showing  the  effects  of 
the  extra  currents  on  induction  currents. 


APPARATUS  EMPLOYED  IN  STUDY  OF  MUSCLE.        375 

extra  current  in  the  reverse  direction.  "When  the  primary  circuit  is  formed, 
there  is  a  secondary  induced  current,  represented  by  curve  2,  placed  below 
h  b,  because  it  is  in  the  opposite  direction  to  I.  On  opening  the  primary  circuit, 
its  current  suddenly  ceases,  as  shown  by  the  vertical  line  3  3,  and  is  unaffected 
by  any  extra  current.  When  the  primary  circuit  is  opened,  an  induced  current 
is  generated  in  the  secondary  coil,  and  this  induced  current  at  once  reaches  its 
maximum,  as  shown  by  the  vertical  line  4  4,  and  then  falls  off  gradually,  as 
shown  by  the  curve  4  4'. 

To  equalize  the  two  currents.  Von  Helmholtz  invented  the  arrangement 
shown  in  Fig.  223.  A  loop  of  wire,  g,  is  carried  from  the  pillar  g  (the  first  pillar 
on  the  left)  in  the  direction  of  the  arrow  to  the  screw/',  and/'  is  screwed  up  so 
that  it  does  not  come  into  contact  with  the  back  of  the  spring  h,  but /is  screwed 
up  so  that  with  each  vibration  of  h,  the  under  surface  of  the  spring  touches  the 
screw  point  /.  The  current  from  the  +  pole  enters  at  A,  and  at  first  passes 
through  the  loop  wire  g  to  /',  thence  to  the  primary  coil  c,  and  thence 
to  the  electromagnet  b.  When  the  soft  iron  core  of  the  latter  is  mag- 
netized, the  hammer  h  is  pulled  down,  and  the  under  surface  of  the  centre 
of  the  spring  touches  the  top  of  the  middle  pillar  at  the  screw  /.  This 
short  circuits  the  primary,  and  the  current  then  returns  to  the  battery  by 
passing  down  the  pillar  a,  and  out  by  the  wire  B  to  the  -  pole.  But  the  closure 
of  the  short  circuit  so  weakens  the  current  flowing  through  the  electromagnet  b. 
that  the  hammer  is  released  and  the  short  circuit  being  broken  at  /,  the  current 
must  pass  by  the  long  circuit,  and  thus  the  current  in  the  primary  coil  c  is  never 
opened,  but  the  opening  shock  in  the  secondary  coil  i  is  due  to  the  weakening  of 
the  current  in  the  primary  at  the  moment  of  short  circuiting.  By  this  method, 
an  extra  current  is  induced  in  the  primary  at  opening  (or  rather  at  the  moment  of 
weakening  the  current  by  short  circuiting),  and  as  this  is  in  the  reverse  direction 
to  the  chief  current  in  the  primary,  the  opening  shock  is  reduced  in  strength,  and 
becomes  nearly  equal  to  the  shock  from  the  secondary  coil  at  the  moment  of 
closing.  The  weakening  of  the  primary  circuit  thus  produced  is  shown  in  Fig. 
224  A'  A",  in  its  diminished  distance  from  B.  When  the  short  circuit  is 
broken,  as  already  described,  the  strength  of  the  primary  is  at  once  increased, 
as  shown  by  the  curved  dotted  line,  1'.  This  increased  strength  of  the  primary 
produces  an  induced  current  in  the  secondary,  as  shown  by  the  dotted  curve  2', 
below  b  II.  The  weakening  of  the  primary  by  the  re-establishment  of  the  short 
circuit  is  pictured  by  the  dotted  curve  3 '.  This  in  turn  produces  an  induced 
current  in  the  secondary  coil,  represented  by  the  curved  line  4'.  Thus,  with  the 
original  arrangement,  the  strength  of  the  closing  induction  shock  is  represented 
by  the  curve  2,  and  that  of  opening  by  the  curve  4  4  4,  while  these  values,  with 
the  arrangement  of  Von  Helmholtz,  are  shown  by  the  curves  2'  and  4',  and  it  will 
be  seen  that  these  curves  are  very  similar  in  appearance. 

When  the  arrangement  of  Von  Helmholtz  is  employed,  there  is  an  extra  current 
in  the  primary  coil,  both  at  the  moment  of  opening  and  of  closing  the  primary 
current,  and  the  extra  current  may  be  employed  as  a  stimulus  by  connecting  the 
positive  and  negative  poles  of  the  battery  with  the  pillars  g  and  a,  and  the  wires 
for  carrying  off  the  extra  current  to  the  tissues  are  connected  to  /'  and  /. 

The  primary  coil  should  consist  of  at  least  432  windings,  hav- 
ing a  resistance  of  1"27  ohm,  and  the  secondary  should  have  14,680 
windings,  with  a  resistance  of  1362  ohms  at  16°  C.     Professor  Bow- 


376 


THE  CONTRACTILE  TISSUES. 


Jitch  has  also  improved  the  iuductorixim  by  having  the  secondary  coil 
mounted  on  a  rotating  disk,  so  that  it  may  be  placed  \vith  its  axis 
forming  an  angle  with  that  of  the  primary.  Thus,  the  strength  of  the 
secondary  current  may  be  modified  according  to  the  amount  of  angular 
deviation,  and  this  may  be  read  off  from  a  gi'aduated  arc  at  the  side  of 
the  base  of  the  secondary  coil.  In  using  the  inductorium  for  physiolo- 
gical purposes,  the  observer  should  always  state  (1)  the  battery  em- 
ployed, so  as  to  indicate  the  e.  m.  f.  ;  (2)  the  number  of  windings  and 
the  resistance  of  the  primary  coil ;  (3)  the  number  of  windings  and  the 
resistance  of  the  secondary  ;  (4)  the  distance  of  the  secondary  from  the 
primary  ;  (5)  Avhether  or  not  Von  Helmholtz's  loop  "svire  was  used  ;  and 
(6)  the  amount  of  angular  deviation  of  the  primary  and  secondary 
coils. 


4.  Accessory  Appliances. 

For  the  purpose  of  opening  and  closing  currents,  various  instruments 
may  be  employed.  One  of  the  most  convenient  is  termed  a  keij,  seen  in 
Fig.  225.  It  consists  of  a  rectangular 
wooden  frame,  by  which  the  key  may  be 
screwed  to  the  table.  On  the  top  is  a  square 
block  of  vulcanite,  a,  bearing  two  rectangular 
bars  of  brass,  h  and  c,  which  may  be  joined 
by  the  handle,  d,  carving  a  horizontal  piece 
of  brass.  The  key  is  closed  when  the  arm  is 
horizontal,  as  in  the  figure.  On  moving  the 
handle,  d,  backwards  and  to  the  right  (see 
Figure),  the  brass  arm  is  raised,  and  of  course 
the  contact  between  h  and  c  is  broken.  The 
key  is  then  said  to  have  been  opened.  Wires 
are  attached  by  binding  screAvs  to  h  and  c. 
If  the  key  is  interposed  in  the  course  of  the 
wire  leading  from  one  of  the  electrodes  of  a 
battery  or  inductorium,  the  circuit  will  be 
broken  when  the  key  is  opened,  and  closed, 
or  formed  when  the  key  is  closed  ;  but  if  the 
positive  and  negative  j^oles  are  connected  re- 
spectively with  h  and  c  by  the  two  inner  bind- 
ing screws,  while  the  two  outer  binding  screws 
have  wires  passing  from  them  to  a  nerve  or 
muscle,  or  to  a  galvanometer,  or  other  electrical  apparatus,  it  is  clear 
that  when  the  key  is  closed  t)ie  battery  current  will  be  short  circuited, 


Fig.  225. — Du  Bois-Reymond's 
friction  key. 


APPARATUS  EMPLOYED  IN  STUDY  OF  MVSCLE.        377 

and  that  when  the  key  is  open,  the  current  will  then  pass  onwards. 
Thus,  the  key  may  be  used  (1)  for  opening  and  closing  a  current,  and 
(2)  for  short  circuiting. 

For  rapid  opening  and  closing  of  a  current,  an  arrangement  like 
Neefs  Interrujptor  may  be  employed,  or  a  vibrating  metallic  sprwg  may  be 
interposed  in  the  circuit,  so  arranged  that,  as  it  vibrates,  a  needle  at 
the  end  of  the  spring  will  make  and  break  contact  by  dipping  into  a 
small  vessel  containing  mercury.^  By  varying  the  length  of  the  spring, 
its  vibration  period  may  be  increased  or  diminished.  An  ordinary 
metronome,  fitted  up  as  represented  in  Fig.  226,  is  also  useful  for  making 


Fig.  226. — Metronome,  arranged  for  making  and  breaking  an  electrical  current. 


and  breaking  currents.  As  the  pendulum  swings  backwards  and  for- 
wards, it  makes  and  breaks  contact  by  dipping  into  the  small  vessels 
containing  mercury.  These  vessels  are  interposed  in  the  circuit  by 
wires  dipping  into  the  mercury,  and  it  is  clear  that  when  the  fork- 
shaped  wire  of  the  metronome  also  dips  into  the  mercury  the  circuit 
will  be  formed.  By  moving  the  slider  of  the  metronome  up  or  doAvn, 
the  number  of  interruptions  may  be  regulated. 

^  A  beautiful  and  most  convenient  spring  of  this  description  is  made  by  the 
Cambridge  Scientific  Instrument  Company,  and  is  very  useful  for  many  purposes. 


378 


THE  COXTRACTILE  TISSUES. 


When  tolerably  strong  currents  are  used,  interrupters  consisting  of  a 
point  dijiping  into  and  out  of  mercury  are  \qtx  ti'oublesome  on  account 
of  oxidation  of  the  surface  of  the  mercurj\  This  difficulty  is  removed 
by  the  use  of  the  ingenious  arrangement  of  Hugo  Kronecker,  shown  in 
Fig.  227.     By  allo-n-ing  a  stream  of  water,  or,  still  better,  of  alcohol,  to 


Fig.  227. — Kronecker's  arraugemeiit  for  securing  clean  raercurial  contact. 

flow  through  the  tube  c,  the  surfecc  of  the  merciu^y  in  o  is  kept  clean  at 
the  place  where  the  current  is  closed  and  opened  by  the  vibrator  g, 
which  establishes  the  current  passing  from  g  to  d. 

It  is  sometimes  necessary-  to  reverse  the  direction  of  a  current.  This 
is  readily  accomplished  by  the  use  of  a  simple  apjjaratus,  termed  PoliVs 
Commutator,  seen  in  Fig.  228. 


Fig.  228. — Pohl's  Commutator.    For  description,  see  text. 


It  is  a  disk  of  wood  A,  haviug  six  little  pits  or  depressions  at  regular  distances, 
to  each  of  which  a  binding  screw  is  attached.      From  the  holes  /  and  Ti  two  wires 


APPARATUS  EMPLOYED  IN  STUDY  OF  MUSCLE.        379 

proceed,  which  are  attached  at  their  outer  ends  to  the  ends  of  the  binding  screws,, 
but  loosely,  so  that  they  may  move  from  side  to  side.  These  wires  pass  into  a 
piece  of  glass  or  vulcanite  n,  but  without  their  inner  ends  touching.  Thus,  a- 
bridge  is  formed  ;  but  if  a  current  entered  the  end  of  the  bridge  by  the  binding 
screw  marked  +  to  the  right,  it  coitld  not  pass  across  to  the  binding  screw  having 
the  wire  —  attached  on  the  left.  Two  curved  wires  k  m  and  q  i  are  soldered  at 
their  centres  to  the  wires  /  and  h,  but  with  the  ends  free.  As  the  bridge  n  can 
rock  backwards  and  forwards,  the  ends  i  m  may  dip  into  the  troughs  of  mercury 
d  c,  or  the  other  ends  k  q  may  dip  into  the  troughs  g  b.  By  this  arrangement, 
when  the  wires  dip  into  c  d,  as  in  the  Figure,  suppose  a  ciirrent  entering  at  +  on 
the  right,  it  would  pass  along  h  i  into  d,  and  out  by  the  curved  wire  x,  round 
the  circuit,  back  to  the  curved  wire  y,  into  vi,  thence  by  1  into  /,  and  thence 
back  to  battery  by  -ware  -  on  the  left.  On  the  other  hand,  if  k  q  dipped  into  g  h, 
the  current  would  go  out  from  b  and  return  to  g.  Thus  the  current,  by  simply 
reversing  the  bridge,  could  be  sent  to  a  circuit  x  y,  or  to  one  represented  by  iv  v. 
Now  suppose  the  cross  bars  o  p  inserted  so  that  p  joins  the  troughs  c  b,  and  o  joins 
d  g  ;  then,  if  a  current  enters  h,  it  will  pass  by  i  into  d,  and  then  out  by  x  to 
circuit,  back  to  y,  then  into  vi,  then  by  1  into  /,  and  back  by  wire  -  to  battery. 
If,  however,  the  bridge  be  reversed  so  that  k  q  dip  into  g  b,  when  the  current 
enters  by  h,  it  will  not  pass  by  i  into  d,  because  the  circuit  is  broken  there ;  but  it 
will  go  by  q  into  b,  then  by  cross  wire  -p  over  to  c,  then  out  by  the  wire  y,  round 
the  circuit  to  x  into  d,  then  by  cross  wire  o  to  g,  then  by  k  up  to  1 ,  and  then  back 
to  battery  by  wire  - .  Thus,  by  the  use  of  the  cross  wires  o  ;;,  if  the  current 
enters  by  the  binding  screw  +  on  the  right,  x  wUl  be  +  pole  if  the  bridge  is  in  the 
position  seen  in  the  Figure,  and  y  will  be  the  +  pole  if  the  bridge  is  reversed  so 
that  k  q  dip  into  g  b.     The  cross  wires  thus  reverae  the  direction  of  the  current. 

The  most  convenient   arrangement   for   stimulating  a  nerve  is  an 
apparatus,  termed  the  Polarizable  Electrodes  of  Du  Bois-Reymond,  seen 


Fig.  229.— Polarizable  Electrodes  of  Du  Bois-Eeymond.  a,  upright  brass  rod  r 
b,  screw  for  tightening  the  rod  c  on  a ;  above  screw  a;  is  a  ball  and  socket- 
universal  joint ;  d  is  a  curved  brass  rod  bearing  A,  a  piece  of  vulcanite,  through 
which  two  wires  pass,  having  binding  screws  e  e'  at  one  end,  and  rectangular 
platinum  points//'  at  the  other. 


in   Fig.   229.      The   nerve   is   laid   across   the   platinum   points  /  /', 
Even  with  such  electrodes,  irritable  nerves  might  be  stimulated  by 


iiSO 


THE  CONTRACTILE  TISSUES. 


•currents  produced  by  polarization  caused  hy  the  action  of  the  animal 
fluids  on  the  metallic  substances.  In  certain  refined  cxi)eriments 
the  nerves  are  stretched  across  Non-polarizaUe  Electrodes,  shown  in 
Fig.  230.  This  form  may  be  used  not  merely  for  stimulating  nerves, 
but,  and  more  especially,  for  conveying  currents  from  nerve  and  muscle 
into  the  circuit  of  a  galvanometer.  (See  the  Chapter  on  the  Electrical 
Phenomena  of  Muscle.)  The  electrodes  here  shown  are  those  used  by 
Professor  Burdon-Sanderson,  but  for  the  purpose  of  stimulating  a  nerve 
they  may  be  of  much  smaller  size.  They  consist  of,  a,  a  brass  stand 
-carrying  a  horizontal  bar  of  vulcanite  h,  which  in  turn  sui)ports  the 
•electrode  c.  Each  electrode  is  a  curved  glass  tube  d,  closed  at  one  end 
by  a  small  piece  of  sculptor's  clay  e,  moistened  with  saliva  or  "vvith  a 


Fio.  230.— Xou-iiolaiizable  Electrodos  of  Burdon-Sanderson. 


'75  per  cent,  solution  of  conuuon  salt,  and  containing  a  saturated  solu- 
tion of  pure  sulphate  of  zinc.  Into  the  other  end  of  the  glass  tube,  there 
is  dipped  a  small  rod  of  amalgamated  zinc.  Such  an  arrangement,  care- 
fully prepared,  is  absolutely  non-polarizable,  so  that  if  a  nerve  or  muscle 
were  laid  across  two  such  electrodes,  and  a  current  from  a  battery  or 
inductorium  were  passed  through  the  nerve  or  muscle,  the  latter  would 
be  stimulated  by  the  current  from  the  electrical  apparatus,  and  by 
nothina;  else. 


APPARATUS  EMPLOYED  IN  STUDY  OF  MUSCLE.        881 

Several  electrical  appliances  are  shown  in  Fig.  231,   and  reference 
is  made  to  the  description  of  the  Figure. 


Fig.  231. — Apparatus  for  electrical  experiments  on  muscle  and  nerve. 
T.  Electro-magnetic  signalling  apparatus  for  recording  seconds  on  a 
revolving  cylinder  ;  a,  bobbins  covered  with  wire  ;  h,  brass  rod  carrying 
pencil  or  pen  ;  c,  steel  spring.  II.  and  III.  Brass  forceps  for  holding  leg 
of  frog  ;  o,  forceps  ;  b,  binding  screw  for  wire.  IV.  Platinum  electrodes 
for  stimulating  nerve  ;  a,  jDiece  of  vulcanite  carrying  glass  plate  c  c,  on 
wliicli  are  the  copper  wires  terminating  in  rectangular  platinum  points  ; 
i,  universal  joint.  V.  Pohl's  commutator  for  reversing  the  direction  of 
electric  currents ;  d  and  e  are  connected  with  the  battery  or  ind\iction 
coil ;  &  c  and  a  f  are  binding  screws  for  attaching  wires  in  different 
circuits  ;  g,  bridge  of  copper  wire,  divided  and  insulated  in  the  centre 
by  glass  tube,  for  the  purpose  of  sending  the  current  entering  by  d  e, 
either  in  the  direction  of  6  c  or  af.  VI.  Du  Bois-Reyrnond's  key,  con- 
sisting of  a  piece  of  vulcanite  on  which  there  are  two  rectangular  pieces 
of  brass  a  b,  each  having  two  binding  screws.  The  two  pieces  of  brass 
are  connected  by  an  arm  of  brass,  the  handle  of  which  is  seen  at  c. 
VII.  and  VIII.  Two  forms  of  apparatus  for  stimulating  nerve,  consisting 
of  vulcanite  troughs,  into  which  are  fixed  platinum  wires,  which  may 
be  attached  to  the  wires  coming  from  the  battery  by  binding  screws 
at  a  a  a  a. 


Chap.  IV.— THE  GRAPHIC  METHOD. 

Many  movements  are  too  rapid  to  be  followed  in  all  their  phases  by 
the  unaided  eye.  For  example,  the  prongs  of  a  tuning-fork  are  in 
active  periodic  motion  during  the  time  that  a  tone  is  emitted  by  the 
fork,  but  the  prongs  may  appear  to  the  eye  to  be  stationary-.  Again, 
the  movements  of  a  bird's  wing  or  of  the  limbs  of  a  quickly-trotting 
horse  are  too  rapid  to  be  followed  by  the  eye.  The  motion  of  the 
living  heart  exposed  in  the  living  animal  seems  so  irregular  and  tumul- 
tuous as  to  make  one  with  no  experience  of  scientific  methods  doubt 
the  possibility  of  tracing  its  various  movements.  Even  when  the 
isolated  muscle  of  a  frog's  limb  is  caused  to  contract  by  irritating  the 
nerve  supplying  it,  the  eye  cannot  tell  whether  the  contraction  occurs 
in  a  shorter  time  than  the  relaxation,  and  still  less  whether  the  con- 


382  THE  CONTRACTILE  TISSUES. 

traction  is  at  a  uniform  rate  in  time,  or  -whether  it  contracts  faster  at 
the  beginning  and  more  slowly  towards  the  end,  or  the  reverse.  Sup- 
pose the  muscle  were  hung  vertically,  and  that  it  was  connected  at  its 
lower  end  to  a  lever,  and  that  the  point  of  the  lever,  bearing  a  pencil, 
^\'ere  brought  against  a  sheet  of  paper  also  placed  vertically,  if  the  paper 
were  moved  horizontally  from  right  to  left,  a  horizontal  line  Avould  be 
drawn  upon  it  by  the  pencil  so  long  as  the  nuiscle  did  not  contract. 
On  the  other  hand,  suppose  the  paper  to  be  stationary  and  the  muscle 
to  contract,  the  pencil  at  the  end  of  the  lever  would  draw  a  vertical 
line,  the  height  of  which,  making  allowance  for  the  am})lification  of 
the  movement  by  the  lever,  wovdd  be  a  measure  of  the  amount  of 
muscular  contraction,  or,  in  other  words,  of  the  shortening  of  the 
muscle.  Finally,  suppose  that,  while  the  muscle  shortened  by  contraction, 
the  sheet  of  paper  moved  at  a  uniform  speed  from  light  to  left,  then  the 
pencil  would  describe  a  line  passing  obliquely  upwards,  and  to  the  right 
(Fig.  2.32,  from  below  the  line  B,  in  direction  a,  c),  so  long  as  the  muscle 

contracted,  and  a  line  obliquely  down 
ward,  and  also  to  the  right,  during  the 
relaxation  of  the  muscle.  Thus,  by 
a  series  of  contractions,  the  zig-zag 
line  would  be  drawn.  If  the  motion 
of  the  contracting-muscle  were  more 
uniform,  then  a  line  like  the  curve 
FiQ.  232 -Diag.-am  illustrating  the  graphic      A  would  be  described.     This  illus- 

method.     No  muscle  would  actually  record 

such  curves.  trates  the  essential  principle  of  the 

graphic  method,  by  which  movements  are  recorded  on  a  surface,  which 
may  be  either  stationary  or  moving  Avith  a  uniform  A^elocity,  a  method 
which  has  been  of  great  value  in  all  sciences  dealing  with  movement, 
and  not  least  to  physiological  science. 

An  excellent  illustration  of  the  graphic  method  is  seen  in  the  tracing 
of  harmonic  motions.  Suppose  two  jiendular  motions  acting  on  the 
same  point,  and  that  the  times  of  the  motions  were  as  1  to  1,  or  as 
1  to  2,  or  as  2  to  3,  or  as  3  to  4,  and  that  the  surface  over  Avhich  the 
point  travelled  was  stationary,  then  the  beautiful  figures  seen  in  Fig. 
233  will  be  described.  If,  however,  the  recording  surface  be  moving 
from  right  to  left,  then  the  forms  of  the  curves  described  by  the  com- 
bination of  the  same  motions  will  be  those  shown  in  Fig.  234. 

This  illustration  shows  that,  hoAvever  complicated  may  be  the  move- 
ments of  a  point,  these  movements  may  be  recorded,  and  that  the 
character  of  the  tracing  on  the  recording  surface  will  vary  according  as 
the  recording  surface  is  stationary  or  moving. 

The  method  of  the  graphic  registration  of  movement  is  not  entirely 


THE  GRAPHIC  METHOD. 


383 


modern.  In  1734,  the  Marquis  d'Ons-en-Bray  described  an  anemometer 
which  recorded  its  movements  on  a  sheet  of  paper,  rolled  round  a 
cylinder,  moved  by  clockwork.  Magellan,  in  1779,  made  designs  for 
an  instrument  he  called  a  "  Meteorograph  "  for  recording  automatically 
many  meteorological  phenomena.     It  was  then  a  dream  to  attempt  to 


Fig.  233.— Lissajous'  figures  of  liamiouic  motions.  A,  1  :  1,  unison  ; 
B,  1  :  2,  oatave  ;  C,  2  :  3,  fifth ;  and  D,  3  :  4,  fourth.  The  figures 
1,  2,  3,  4,  and  5  in  each  row  represent  the  phases  of  the  harmonic 
motions. 

record  buch  phenomena,  but  it  has  become  a  reality  in  these  latter  days. 
A  thermometer  was  described  by  Eutherford  in  1794,  by  which  the 
curves  ot  fluctuating  temperatures  were  recorded  on  blackened  paper. 
About'1800,  Thomas  Young  showed  how  time  can  be  measured  on  the 
surface  of  a  cylinder  moving  at  a  uniform  speed.    The  celebrated  James 


Fig.  234. — Figures  of  harmonic  motions,  with  recording  surface  moving 
from  right  to  left.     A,  Unison ;  B,  1  :  2,  octave. 

Watt,  at  a  date  I  have  been  unable  to  fix,  devised  a  method  of  tracing 
the  movements  of  the  indicator  of  his  engine  on  a  cylinder  rotated  by 
the  engine  itself.     Thus,  he  obtained  a  curve  representing  variations  of 


384 


THE  CONTRA  CTILE  TISSUES. 


steam  pressure  at  different  times. ^  A  method  of  recording  the  oscil- 
lations of  mercury  in  a  manometer  was  invented  by  Ludwig,  and 
resulted  in  the  kymograph,  or  recorder  of  blood  pressiu'e,  and  during  the 
past  tAventy  or  thirty  years  numerous  ingenious  instruments  have  been 
invented  by  physiologists  for  recording  movements.  No  physiologist 
has  done  more  in  this  direction  than  Marey,  to  whom  we  are  largely 
indebted  for  the  development  of  the  graphic  method  to  its  present 
condition  of  precision  and  convenience. 


I.  Measurement  of  Time  or  Chronography. 

As  many  of  the  phenomena  of  nervous  and  muscular  actions  are  of 

such  short  duration  as  to  make  it 
imj)ossible  to  observe  their  phases 
with  the  unaided  senses,  it  is  neces- 
sary to  construct  apparatus  for  the 
measurement  of  minute  intervals  of 
time.  Accordingly,  in  recent  years, 
much  ingenuity  has  been  expended 
in  the  construction  of  chronographic 
or  time-measuring  instruments,  of 
which  the  following  are  examples — 
(a)  Recording  Cylinder.  —  This  is 
a  cylinder  revolving  at  a  uniform 
rate  by  means  of  clockwork.  Sup- 
pose the  surface  of  the  cylinder  to 
be  divided  by  sixty  lines,  parallel 
Avith  its  axis,  at  equal  distances 
from  each  other,  and  that  the  cylin- 
der makes  one  revolution  in  a 
second,  the  distance  between  tAvo 
of  the  lines   will   represent  the  gV 

Fig.    235.— Original   Chronometer   devised   by  part    of    a    SCCOnd,     aud    any    phcuO- 

homas  Young  for  measuring  time,     a,  Cylin-  . 

der  rotating  on  vertical  axis  ;  6,  weisrht  acting  nieuon      rCCOrded      OU     the     movillg 
as  motive  power  ;  c,  d,  small  balls  for  regulat-  .  "" 

ing  by  centrifugal  action  the  velocity  of  the  cylinder  between  the  tWO  lllieS  mUSt 
cylinder  ;   e,  marker  recording  a  line  on  the  _    -       .  .  .  - 

cylinder    This  illustration  is  given  to  show    have  happened  dunug  that  interval 

the    form    of    the    first    apparatus    used    for        „       .  t       •  •  i       ,      i_i     j_     i 

chronographic  tracings.  01    time.       it   IS    evident   that    by 

means  of  such  an  arrangement,  seen  in  Fig.    235,  first  suggested  by 

1  Marey,  La  Methode  Graphique  dans  Its  Sciences  Experimentales,  p.  113.  For  a 
view  of  Watt's  Indicator  used  with  the  steam  engine,  as  constructed  by  Watt, 
and  improved  by  M 'Naught  and  Richards,  see  Clerk  Maxwell's  Theory  of  Heat, 
third  edition,  p.  154. 


THE  GRAPHIC  METHOD.  385 

Thomas  Young,  ^  intervals  of  time,  even  to  the  y-oV-o  of  ^  second, 
may  be  measured  T\dth  accuracy.  The  difficulty  in  such  graphic 
measurements  of  time  is  to  cause  the  cylinder  to  revolve  at  a 
uniform  rate.  This  is  accomplished  by  means  of  regulators,  of  which 
the  simplest  is  that  of  Foucault,  now  attached  to  all  revolving  cylinders 
used  for  physiological  purposes.  To  obtain,  on  a  revolving  cylinder 
(the  time  occupied  by  a  revolution  of  which  is  not  known)  continuous 
registration  of  minute  intervals  of  time,  it  is  necessary  to  make  use  of  a 
chronograph. 

(b)  Chronographs.- — Thomas  Young  was  also  the  first  to  devise  the 
method  of  inscribing  upon  a  rotating  cylinder  all  the  vibrations  of  a 
metallic  rod  bearing  a  very  light  style  or  marker.  ^"\Tien  these  vibra- 
tions are  isochronous,  each  of  the  undulations  traced  upon  the  cylinder 
corresponds  to  a  regular  interval  of  time.  Duhamel  was  the  first  to 
apply  to  one  of  the  limbs  of  a  tuning-fork  a  small  marker,  which  traces 
Avith  great  regularity  the  vibrations  of  the  tiuiing-fork,  and  in  this  way, 
if  the  surface  receiving  the  tracing  is  mo\dng  with  sufficient  rapidity, 
intervals  of  the  -g^-g-  of  a  second,  or  less,  may  be  readily  measured. 
An  example  of  tracings  thus  obtained  is  seen  in  Fig.  236. 


Fig.  236. — Tracings  of  the  vibrations  of  a  tuning-fork,  10  vibrations  per 
second,     a,  b,  cylinder  moving  rapidly ;  c,  d,  cylinder  moving  slowly. 

It  is  difficult  to  apply  the  vibrating  limb  of  a  tuning-fork  to  a  re- 
volving cylinder  or  other  moving  surface,  more  especially  if  other 
recording  apparatus  is  adjusted  to  the  cylinder  at  the  same  time.  To 
record  more  easily  vibrations  indicating  time,  an  arrangement  consisting 
of  a  marker,  vibrating  in  unison  "with  a  tuning-fork,  which  is  kept  in 
action  by  the  interruptions  of  an  electric  current,  is  much  employed. 
The  apparatus,  as  applied  to  a  revolving  cylinder,  is  seen  in  Fig.  237. 
The  arrangement  of  apparatus  consists  of  three  parts— a  battery,  an 
interrupting  tuning-fork,  and  the  chronograph.  The  latter,  seen  in 
Figs.  238  and  239,  consists  of  a  very  fine  stylet  fixed  at  the  extremity 
of  a  steel  spring,  and  armed  with  a  small  mass  of  steel,  somewhat 
wedge-shaped,  which  fits  in  between  two  small  keepers,   b  i,  of  the 

1  Thomas  Young's  Lectures  on  isatiiral  Philoioiijhy ;  Lecture  xvii.,  on  Time- 
keepers.    Plate  XV.  Fig.  19S. 

I.  2b 


386 


THE  CONTRACTILE  TISSUES. 


electro-magnets,  a  a.  The  tmiing-fork  interrupts  the  current  from  the 
battery.  This  it  does  automatically.  When  the  iron  of  the  electro-magnet 
between  the  limbs  of  the  tuning-fork  becomes  magnetic,  the  limbs  are 
approximated,  and  a  small  piece  of  platinum  wire  affixed  to  one  of  them 
is  removed  from  contact  Avith  a  platinum  surface  (Fig.  237,  i),  so  as  to 


Fig.  il37.— Chronograph  applied  to  revolving  cylinder,  a,  Grenet's  element; 
b,  wooden  stand  bearing  taniug-fork,  vibrating  2u0  times  per  second  ;  c, 
electro-maguet  between  limbs  of  the  fork;  <(,  e,  positions  for  tuning- 
forks  of  100  and  50  vibrations  per  second  ;  /,  tuning-fork  lying  loose, 
which  may  be  applied  to  d;  (j,  revolving  cylinder;  A,  chronograph 
vibrating  s3mchronously  with  the  tuning-fork.  Current  is  interrupted 
at  i.  Foucault's  regulator  is  seen  over  the  clockwork  of  the  cylinder,  to 
the  right  of  ij. 

break  the  circuit.  On  the  circuit  being  thus  broken,  the  electro-magnet 
ceases  to  act,  the  limbs  of  the  tuning-fork  recede  from  it,  so  as  to  bring 
the  platinum  ^vive  again  into  contact  with  the  platinum  siu-face,  and 
thus  again  to  complete  the  circuit.     The  chronograph  thus  vibrates  in 


Fig.  23S. — Side  view  of  chronograph,  a  a,  coils  of  wire ;  &  b,  keepers  of  electro-magnets  ; 
c,  vibrating  style  fixed  to  steel  plate  e;  d,  binding  screws  for  attachment  of  wires;  +, 
from  tuning-fork  ;  — ,  passing  to  battery. 

imison  with  the  tuning-fork.  The  great  advantages  of  this  apparatus  are 
its  accuracy  and  facility  of  ready  adjustment,  and  it  can  frequently  be 
appKed  where  it  would  be  extremely  difficult  to  bring  the  ttming-fork 
into  direct  contact  Avith  the  movina;  surface. 


THE  GRAPHIC  METHOD. 


387 


N- 


A  very  convenient  form  of  interrupting  tuning-fork,  made  by  the  Cam- 
bridge Scientific  Instrument  Company, 
is  slio'vvn  in  Fig.  240,  and  it  is  here  in- 
troduced to  indicate  the  position  of  the 
electro-magnet  between  the  limbs  of  the 
fork.  Along  with  the  interrupting 
tuning-fork,  the  same  makers  supply  a 
time-marker  (Fig.  241)  for  recording  on 
a,  surface  of  smoked  paper,  and  a  time- 
marker  (Fig.  242),  having  at  the  end  a 
kind  of  syphon  pen,  for  recording  in  ink 
on  a  long  continuous  band  of  white  paper. 
The  latter  arrangement  is  especially 
useful  where  it  is  necessary  to  obtain  a 

1  ,-  i         •  rrn  1         •  Fig.  239. — Front  view  of  clironoffrapli,  to 

lOna;  COntmUOUS  tracmg.      i  he  mechanism    show  positton  of  vibrating  marker.  Same 


of  both  instruments  is  seen  on  inspecting 
the  figures. 


description  as  given  of  last  figure. 


Fig.  240. — Interrupting  or  Chronographic  Tuning-fork  of  Cambridge  Scientific  Instrument 

Company. 


Fig.  241. — Time-marker  of  Cambridge  Scientific  Instrument  Company  for  recording  on  a  surface 

of  smoked  paper. 

(c)  Electrical  Signals. — It  is  often  of  great  importance  to  determine 
the  moment  of  the  commencement  or  termination  of  a  phenomenon. 


388 


THE  CONTRACTILE  TISSUES. 


This  is  readil}'  done  h\  means  of  electro-magnetic  arrangements,  such 
as  are  seen  in  Fig.  243.     The  apparatus  consists  of  two  electro-magnetic 

/11 


Fig.  242. — Time-marker  for  recording  with  ink  when  a  tracing  is  taken  on  white  paper. 

bobbins,  which,  the  moment  the  current  passes,  attract  a  steel  plate 
placed  above  them,  and  draw  down  the  "\n4ting  stylet,  so  as  to  make  a 
lower  horizontal  line.     "When   the  current  is  interrupted,   the  spiral 


Fig.  243. — Aijparatus  for  recording  electro-magnetic  signals  ou 
a  revolving  cj'linder.  a  a,  bobbins  covered  with  wire  ;  b,  steel 
plate  fixed  in  a  frame,  which  is  pulled  downwards  when  the  iron 
cones  of  the  bobbins  become  naagnetic  ;  c,  steel  spring,  by  the 
elasticity  of  which  the  plate  is  drawn  quickly  iiiiwards  when 
released  from  the  bobbins  ;  d,  rod,  bearing  a  marker,  recording 
on  the  cylinder/  at  e. 

spring  elevates  the  lever,  which  traces  an  upper  horizontal  line  imtil  th& 
current  is  again  closed.  The  current  may  be  opened  or  closed  by 
means  of  the  seconds  pendulum  of  a  clock,  by  a  tuning-fork  (Fig.' 240),. 


THE  GRAVHIC  METHOD. 


389 


or  by  a  metronome  (Fig.  226).     By  such  an  arrangement  for  closing  or 
opening  the  circuit,  the  instant  of  the  commencement  or  termination 


Fig.  244. — 1,  Line  drawn  by  marker  of  apparatus  shown  in  Fig.  243 ;  2, 
'  vibrations  of  tuiiiug-fork,  iO  vibrations  per  second  ;  5,  signal,  the  rise  in 
tracing  1  indicates  the  interruption,  and  the  fall  shows  the  formation  of 
the  current,  whilst  the  cj-linder  was  rotating  quickly;  3,  4,  0,  show 
similar  tracings,  but  with  cylinder  going  raore  slowly. 

of  any  phenomenon  will  be  recorded.    An  example  of  a  tracing  obtained 
by  such  an  apparatus  is  given  in  Fig.  244. 


Fig.  245. — Signal  of  Deprez,  as  made  by  the  Cambridge  Scientific 
Instrument  Company. 

A  delicate  form  of  apparatus  for  recording  signals,  similar  in  principle 
to  the  chronograph  shown  in  Figs.  238  and  239,  but  much  smaller,  is 


Fig.  246. — Tracing  taken  with  the  signal  of  Deprez,  acted  on  by  a  current  in- 
terrupted by  a  tuning-fork,  vibrating  500  times  per  second. 

■called  the  signal  of  Depre~.      It  is  represented  in  Fig.   245,  and  an 
•example  of  a  tracing  is  given  in  Fig.  246, 


2.  The  Direct  Recording  of  Movement. 

Movements  may  be  recorded  if  we  attach  a  lever  to  the  moving 
structure,  as  near  the  fulcrum  as  possible,  and  bring  the  other  end  of 
the  lever  into  contact  with  the  recording  surface,  or  the  lever  may 


390 


THE  CONTRACTILE  TISSUES. 


simply  be  laid  on  the  moving  part,  so  that  it  may  rise  and  fall  with  each 
movement.  In  the  case  of  muscular  movements,  special  registering  in- 
struments have  been  invented  termed  Myograplis.  The  first  myography 
invented  by  Yon  Helmholtz,  consists  of  a  brass  framework,  Fig.  247^ 


Fir,.  247. — Myograpli  of  Von  Helmholtz,  shown  in  an  incomplete  form,  a, 
forceps  for  holding  femur  of  frog ;  b,  gastrocnemius  muscle  ;  c,  sciatic  nerve  ; 
d,  pan  for  weights;  e,  marker  recording  on  cylinder  g;  f,  counterpoise,  by 
moving  which  the  weight  of  the  framework  may  be  reduced. 

movable  round  a  horizontal  axis,  and  kept  in  equilibrium  by  a  counter- 
weight. The  tendon  of  the  muscle  is  fixed  by  a  hook  to  the  middle  of 
the  frame,  and  a  balance  for  the  purpose  of  carrying  weights  is  attached 
underneath.  From  the  other  extremity  of  the  brass  framework  there 
hangs  a  marker,  w^hich  traces  uj^on  any  surface  the  movements  of  ascent 
or  of  descent  of  the  muscle.  The  registering  surface  may  consist  either 
of  a  stationary  plate  of  smoked  glass,  as  in  the  arrangement  of  Fick  (see 
Fig.  15,  p.  2S),  or  of  a  vertical  rotating  cylinder  (Fig.  256).  When  the 
tracing  is  obtained  by  Fick's  method,  it  consists  of  a  series  of  vertical 
lines,  as  seen  in  Fig.  16,  p.  29. 

A  convenient  form  of  myograph  is  the  spring  inyograph  of  Du  Bois- 
Reymond,  sho^\Ti  in  Fig.  249.  This  consists  of  a  rectangular  glass  plate,, 
h,  moving  horizontally  along  two  slender  steel  wires,  d.  It  may  be 
impelled  hoxdzontally  by  the  recoil  of  a  steel  spring,  c,  when  a  check  is 
set  free  at  the  other  end  of  the  apparatus.  Thus  applied,  the  muscular 
contraction  will  produce  a  curve.    (See  Fig.  248.)     By  removing  the  rod 


THE  GRAPHIC  METHOD. 


391 


carrying  the  steel  spring,  the  smoked  glass  plate  may  be  slowly  moved 
in  front  of  the  stylet  by  means  of  a  long  screw  attached  to  the  plate,  the 
handle  of  which  is  seen  a  little  below  c.  The  spring  myograph  is  sho^\Ti 
on  a  larger  scale  in  Fig.  248.     See  description  of  Figure. 


Fig.  248. — Spring  Myograph  of  Du  Bois-Reymond.  A  B,  metal  pillars  to  which 
the  wires,  k  k,  are  attached,  and  along  Jc  k  the  frame  carryinif  the  glass  plate  slides 
in  the  direction  of  the  arrow  when  the  spring  b  is  released  ;  d,  short  bar  of  metal 
projecting  from  lower  surface  of  frame  which  opens  the  key  h  when  the  frame  is 
carried  across  by  recoil  of  spring  6.  Thus  the  primary  circuit  of  an  inductorium 
may  be  mechanically  interrupted. 

In  Von  Helmholtz  and  Fick's  arrangement,  whether  applied  to  a 
cylinder  or  to  a  moving  glass  plate,  the  muscle  must  be  placed  in  a 


Fig.  249. — Spring  Myograph,  showing  Chronograph  applied  to  it  for  the 
purpose  of  ascertaining  the  velocity  with  which  the  blackened  glass  plate 
6  is  drawn  across  by  the  recoil  of  the  spring  c. 

vertical  position  and  have  a  certain  weight  to  bear.      Nor  can  the 
apparatus  be  conveniently  applied  to  the  muscle  while  in  situ  in  the  body 


392 


THE  CONTRACTILE  TISSUES. 


of  the  animal  recently  killed.  There  are  thns  a  want  of  sensitiveness 
and  a  want  of  convenience,  hoth  of  which  are  to  a  great  extent  obviated 
by  the  myograph  of  Marcy.  The  arrangement  of  this  apparatus  for  an 
experiment  is  seen  in  Fig.  250. 

The  principal  piece  of  the  apparatus  consists  of  a  horizontal  brass 
plate  supporting  the  axis  of  a  registering  lever,  which  moves  in  a  hori- 
zontal plane.  Consequently  the  lever  registers  upon  a  cylinder  moving 
horizontally.  A  thread  attached  to  the  tendon  of  the  gastrocnemius 
muscle  of  the  frog  is  fixed  by  a  small  button  to  the  lever.  Fixed  to  the 
brass  plate,  and  upon  the  same  plane,  there  is  a  flat  piece  of  cork  on 
which  the  pithed  or  decapitated  frog  is  laid  (in  which  consequently  all 
sensation  has  been  abolished). 


Fig.  250. — Arrangement  of  apparatus  for  experiment  with  the  Myograph 
of  Marey.  a,  recording  cylinder;  b,  railroad  carrying  the  myograph  c; 
d,  galvanic  element ;  e,  induction  coil ;  /,  key. 

A  view  of  the  apparatus  is  shown  in  Fig.  251.  Attached  to  the  side 
of  the  cork  plate,  there  is  a  brass  support  bearing  the  electrodes  for 
stimulating  the  nerve  or  muscle.  When  the  muscle  is  stimulated  elec- 
trically, it  contracts  and  moves  the  horizontal  lever,  which  traces  a 
curve  upon  the  moving  cylinder.  If  it  be  desirable  to  have  a  series  of 
tracings  from  a  muscle  for  a  considerable  period  of  time,  these  may  be 
obtained  by  placing  the  entire  apparatus  upon  a  support,  moved  by 
clockwork  upon  a  little  railroad  (see  Fig.  251)  parallel  with  the  register- 
ing cylinder.  Marey  has  also  devised  a  double  myograph,  which  differs 
from  that  just  described  only  by  having  a  second  lever,  so  that  the  two 
gastrocnemei  of  a  frog  may  be  attached  each  to  a  lever  ;  the  two  levers 


THE  GRAPHIC  METHOD. 


393 


are  superposed,  and  the  tracings  are  close  together  but  still  distinct. 
By  such  an  arrangement  it  is  possible  to  study  graphically  the  forms  of 
the  curves  obtained  by  the  contractions  of  two  muscles  under  different 
conditions,  say  the  one  poisoned  and  the  other  normal. 


Fig.  251. — Jlarey's  myograijh.  A,  pillar  ;  B,  horizontal  metal  plate  ;  (',  screw  for 
adjustinfj  the  height  of  the  marker,  so  that  it  may,  E,  descend  ou  the  surface  of  a 
horizontally  moving  cylinder,  by  moving  the  lever,  D  ;  //,  pulley  for  thread  ;  F, 
thread  from  gastrocnemius  to  lever  ;  &,  /,  spring  for  bringing  lever  back  to 
original  position  during  relaxation  of  muscle. 

The  great  advantage  of  Marey's  method  is  that  it  registers  the  curve 
of  muscular  contraction  so  as  to  give  its  different  phases  of  movement. 
This  will  be  appreciated  upon  comparing  the  two  tracings  seen  in  Figs. 
252  and  253,  which  show  the  changes  in  muscular  contraction  under 


Fig.  252. — Myographio  tracing  obtained  by  the  method  of  Fiok  :  changes 
in  the  amplitude  of  contractions  of  a  muscle  under  the  influence  of  a 
gradually  increasing  temperature,  a,  &,  c,  individual  contractions.  To 
be  read  from  left  to  right. 

the  influence  of  a  gradually  increasing  temperature.  It  maj-  lie  observed 
in  both  that  the  rise  of  temperature  increases  the  amplitude  of  the  con- 
traction, but  the  vertical  lines  do  not  indicate  whether  or  not  any 
change  has  taken  place  in  the  duration  of  the  contraction.     It  mil  be 


394 


THE  cos  TRACTILE  TISSUEIS. 


seen,  however,  l)y  studying  Fig.  253  that  heat  not  only  changes  the 
amplitude,  but  causes  the  contraction  and  relaxation  to  occur  in  shorter 


h'lQ.  i'j;!— Myograpbic  tracing  obtained  bj'  the  metliod  of  Maroy,  corre- 
sponding to  a  g7-adiial  heating  of  a  muscle,  as  in  Fig.  'Ib'l.  U  will  be 
noticed  that  not  only  does  the  amplitude  of  the  contractions  change,  but 
also  their  form  and  their  duration.     To  be  read  from  left  to  right. 

intervals  of  time.     This  is  a  good  example  of  the  value  of  the  graphic 
method  of  resiistration. 


3.  The  Transmission  of  Movement. 

One  of  the  chief  difficulties  in  the  registration  of  animal  movements 
is  that  of  attaching  directly  to  the  body  a  marker  which  will  inscribe  on 
a  blackened  surface  the  phases  of  the  movement.  It  is  therefore  neces- 
sary to  have  means  of  transmitting  the  movement  to  a  distance,  or,  in 
other  Avords,  transferring  to  the  i"ecording  surface  the  movement  we 
Avish  to  examine.  This  Marey  has  accomplished  by  the  use  of  tambours, 
or  drums,  united  by  tubes  containing  air.  One  of  these  tamboiu's  is 
seen  in  Fig.  254.  It  consists  of  a  shallow  metallic  case,  or  drum,  the 
upper  surface  of  which  is  formed  by  a  thin  indiarubber  membrane  su])- 


Fi<i.  204. — Tambour  of  Marey.  a,  metallic  case  ;  b,  thiu  indiarubber 
membrane;  c,  thin  disk  of  aluminium  supporiing  the  lever,  d,  only  a 
small  portion  of  which  is  represented  ;  e,  screw  for  adjusting  the  support 
of  the  lever  vertically  over  c  ;  /,  metallic  tube  comnninlcating  with  the 
cavity  of  the  tambour  for  attachment  to  an  indiarubber  tube. 

porting  the  writing  lever.  Two  tambours,  each  ha-vang  a  short  metallic 
tube  communicating  Avith  its  interior,  may  be  connected  together  by 
carrying  an  indiarubber  tube  from  the  one  metallic  tube  to  the  other, 
as  represented  in  Fig.  255. 

When  the  membrane  of  the  first  tambour  is  depressed,  part  of  the  air 
which  it  contains  is  expelled  ;  this  air  passes  through  the  indiarubber 
tube  into  the  second  tambour,  the  membrane  of  Avhich,  carrying  the 
lever,  is  elevated.     On  the  contrary,  when  the  first  tambour  is  not  acted 


THE  GRAPHIC  METHOD. 


395 


upon,  the  membrane  of  the  second  returns  to  its  former  position.  The 
first  may  be  termed  the  receiving,  and  the  second  the  registering,  tam- 
bour.    It  Avill  be  observed  that,  as  above  arranged,  the  movements  of 


Fig.  255. — Tambourb  of  llarey  arranged  for  the  transmission  of  movement,  a,  receiving- 
tambour  ;  h,  iudiarubber  tube;  c,  registering  tamVjour ;  d,  spiral  of  wire,  by  the  elasticity 
of  which,  when  the  tension  is  removed  from  a,  the  lever  ascends. 


Fi«.  256. — Arrangement  of  re^iistering  tambours,  a,  a,  a,  for  recording  three  movements 
on  cylinder  d.  The  tubes  communicating  between  the  recording  and  registering  tambours 
are  seen  at  6,  b,  b.     The  chronogi-aph  is  represented  at  c. 


imi 


THE  CON  TRACT  I  Lie  TISSUES. 


the  registering  tanil>our  are  in  opi)osite  directions  :  when  the  mem- 
brane of  the  one  is  drawn  downwards,  that  of  the  other  is  forced 
upward.  When  it  is  desirable  to  obtain  the  movements  of  the  levers 
in  the  same  direction,  one  of  the  tambours  must  be  reversed.  What 
lends  liTeat  value  to  this  method  of  transmission  of  movement  is  that 


Fig.  257. — Arraiigemeiit  of  iqiparalus  lor  tiaiiMmbSiuu  ot  uuisciilar  move- 
ment by  tambours,  a,  voltaic  element;  b,  primary  coil;  c,  secondary 
coil  of  inductorium  ;  </,  metronome  for  intei-rupting  primary  circuit, 
when  induction  current  is  sent  to  electrodes  k  \  h,  forceps  for  feni\ir  ;  the 
muscle,  which  is  not  here  represented,  is  attached  to  the  receiving  tam- 
bour, (I,  by  which  movement  is  transmitted  to  the  recording  tambour,  e, 
which  writes  on  the  cylinder,  _/'. 

it  is  possible  to  register  upon  the  same  recording  surfiice  a  series  of 
movements  occurring  in  different  localities,  so  as  to  have  the  means  of 
comparing  their  rhythm,  duration,  and  character.  In  Fig.  256,  an 
arrangement  is  rejjresentcd  by  which  three  movements,  along  with  a 
chronographic  tracing,  may  be  obtained  on  the  same  cylinder. 


Fig.  258. — Vibrations  of  tuning-fork  transmitted  by  tambours.  1,  10 
vibrations  per  second ;  2,  10  vibrations  per  second,  with  smaller 
vibrations  at  rate  of  80  per  second  seen  on  the  larger  curves  ;  3,  50 
vibrations  per  second ;  4,  100  vibrations  per  second. 

Marey  has  also  applied  his  method  of  transmission  of  movement  to 
the  phenomena  of  muscular  contraction.  By  causing  the  contracting 
muscle  to  act  on  a  tamboiu",  as  seen  in  Fig.  257,  the  movement  may  be 
carried  to  a  di.stance  to  a  recording  tambour  in  connection  with  a  cylin- 


THE  GRAPHIC  METHOD.  397 

der.  By  this  ingenious  method  it  is  possible  to  subject  the  muscle  to 
different  temperatures,  or  to  the  action  of  various  gases,  without  inter- 
fering in  any  way  Avith  the  recording  apparatus. 

Numerous  adaptations  of  Marey's  method  ^\all  be  pointed  out  in  dis- 
cussing the  physiology  of  the  organs.     It  suffices  to  state  here  that  the 


Fig.  250. — Tracing  taken  with  lambours,  sliowiug  in  line  a  beats  of  the 
anterior  fontanelle  of  an  infant  of  6  weeks  during  sleep  ;  and  in  line 
c  the  thoracic  movemeiits  in  breathing. 

tambours,  when  in  good  order,  are  remarkably  sensitive.  Thus  thej' 
may  record  even  the  vibrations  of  a  tuning-fork  as  shown  in  Fig.  258, 
and  they  can  record  the  delicate  pulsatile  movements  seen  in  the  anterior 
fontanelle  of  a  child's  head  (Fig.  259). 


Chap.  V.— THE  PHYSICAL  PROPERTIES  OF  MUSCLE. 

The  physical  properties  of  muscle  Avhich  are  of  physiological  interest 
are  consistence  or  degree  of  firmness,  cohesion,  and  elasticity. 

1.  Consistence. — When  a  muscle  is  in  the  contracted  condition,  it  is 
hard  and  resistant,  and  when  it  is  relaxed  it  is  soft.  The  matter  within 
the  sarcolemma  is  soft  and  jelly  like,  but  in  the  state  of  rigidity  which 
follows  death  it  undergoes  a  change  and  becomes  firm  and  almost  solid. 
The  semi-fluid  condition  of  the  matter  of  living  muscle  is  indicated  b}- 
various  phenomena.  Thus,  it  may  be  scjueezecl  out  of  the  sarcolemma 
by  the  use  of  a  compressor  whilst  under  the  microscope.  Wave-like 
movements,  indicating  a  semi-fluid  condition,  occur  in  living  muscle. 
A  parasitic  worm  {BIyoredes  Weismanni)  has  been  observed  to  push  its 
way  through  the  jelly-like  matter  of  a  living  muscular  fibre,  not  by  bor- 
ing a  tunnel  as  it  would  have  done  in  a  solid  substance,  but  moving 
freely  as  if  it  were  in  a  viscous  mass.  Streaming  movements  or  currents 
have  also  been  detected,  flowing  from  the  positive  to  the  negative  j)ole, 
when  a  voltaic  current  was  passed  from  end  to  end  of  a  living  fibre. 
This  is  termed  Forrefs  ex;periment,  and  shows  clearly  that  the  physical 
constitution  of  the  muscle  substance  is  semi-fluid  like  that  of  other 
varieties  of  protoplasm. 

2.  Cohesion. — The  cohesion  of  muscular  tissue  is  much  more  feeble 
than  that  of  the  connective  tissues,  and  especially  than  that  of  tendon. 
According  to  E.  Weber,  a  square  centimetre  of  frog's  muscle  avIII  support 


398  THE  CONTRACTILE  TISSUES, 

the  weight  of  a  kilogramme  without  rupture.     The  disappearance  of 

muscular  irritability,  which  occurs  as  a  muscle  gradually  dies,  is  accom- 
})anied  by  a  diminution  of  cohesion.  The  gastrocnemius  of  a  dead  frog, 
for  example,  Avhich  has  lost  its  irritability,  may  be  torn  across  by  a  weight 
of  about  260  grammes,  Avhile  a  similar  muscle  from  a  frog  just  killed 
may  sustain  without  rupture  a  Aveight  of  1|-  kilogramme.  This  experi- 
ment not  infrequently  foils  from  the  muscle  being  torn  across  at  the 
junction  of  the  muscular  fibre  with  the  tendon. 

3.  Elasticity. — The  elasticity  of  living  muscle  in  a  state  of  rest  is  small, 
but  nearly  perfect ;  that  is,  the  muscle  will  elongate  easily  under  the 
influence  of  very  small  weights,  and  will  return  on  their  removal  exactly 
to  its  former  length.  We  may  readily  study  this  physical  question  by 
using  the  myograph  of  Von  Helmholtz.  The  amount  of  stretching 
caused  by  different  weights,  placed  in  the  pan  (see  Fig.  15,  p.  28), 
may  be  readily  recorded  on  the  smoked  glass  plate.  It  will  then  be  seen 
that  the  elongations  of  the  muscle  are  not  proportional  to  the  weights 
Avhich  stretch  it.  A  rough  experiment  may  show  that  the  amount  of 
stretching  is  proportional  to  the  amount  of  heavier  and  heavier  weights; 
but  careful  observation  proves  that  the  amount  of  extension  or  stretching- 
diminishes  as  the  weights  increase,  so  that  the  curve  of  muscular  extensi- 
bility approaches  that  of  a  hyperbola,  and  is  not  a  straight  line  as  is  the 
case  with  most  inorganic  bodies.  To  obtain  the  curve,  mark  in  a  hori- 
zontal line,  as  abscissse,  successive  units  of  weight,  and  from  these  draw 
lines  or  ordinates  of  lengths  corresponding  to  the  amount  of  extension. 
A  curve  touching  the  ends  of  these  ordinates  will  be  found  to  be  the 
curve  of  a  hyperbola.  In  other  words,  the  amount  of  the  elasticity  of  a 
muscle  increases  as  it  is  stretched.  The  elasticity  of  dead  muscle  is  very 
much  greater  than  of  living  muscle,  but  it  is  imperfect.  That  is  to  say, 
a  dead  muscle  requires  a  greater  weight  to  stretch  it  to  a  given  amount, 
and  when  the  weight  has  been  removed  it  remains  elongated  to  a 
considerable  extent. 

The  limit  of  elasticity  of  living  muscle  is  readily  passed.  Marey  has 
shown  that  the  gastrocnemius  of  a  frog,  weighted  with  100  grammes, 
will  not  return  to  its  primitive  length. 

According  to  Weber,  the  elasticity  of  an  active  muscle,  that  is  of  a 
muscle  in  a  contracted  condition,  is  diminished.  He  arrived  at  this 
result  by  tetanizing  the  hjoglossus  muscle  of  a  frog  securely  fixed  at  one 
end  and  having  weights  attached  to  the  other.  He  compared  the  amount 
of  elongation  during  the  state  of  contraction  with  elongations  caused  by 
the  same  weights  upon  the  same  muscle  in  repose.  He  found,  l)y  this 
method,  a  greater  elongation  in  the  contracted  muscle  produced  by  a 
Aveight  of  one  or  two  grammes  than  when  the   same  weio-hts  were 


THE  PHYSICAL  PROPEttTIES  OF  MUSCLE.  399 

attached  to  the  muscle  in  repose.  He  also  made  the  following  curious 
observation,  often  termed  JFeher's  imradox,  that  if  a  muscle  in  repose  is 
heavily  weighted,  and  then  stimulated,  it  may  become  longer  instead  of 
shorter ;  that  is  to  say,  the  shortening  due  to  contraction  is  not  sufficient 
to  compensate  for  the  elongation  due  to  diminution  of  the  elasticity. 
Volkmann  pointed  out,  after  an  elaborate  research,  in  which  he  did  not 
employ  tetanic  excitations,  as  Weber  had  done,  but  isolated  ojjening 
induction  shocks,  that  Weber  had  exaggerated  the  diminution  of  elas- 
ticity in  active  muscle,  and  that  the  results  are  largely  affected  by  the 
condition  of  fatigue.  Wundt  has  also  arrived  at  results  contrary  to  those 
of  Weber.  He  adopted  the  method  of  arresting  by  an  overweight  the 
contraction  of  a  muscle,  and  he  found  that  the  diminution  of  muscular 
elasticity  does  not  depend  upon  the  state  of  activity,  but  simply  upon 
shortening  of  the  muscle.  He  says,  "If  the  diminution  of  elasticity 
depends  upon  the  state  of  activity,  it  would  folloAV  in  my  mode  of  experi- 
menting, that  at  the  moment  of  excitation  there  ought  to  be  an  elonga- 
tion of  the  muscle,  its  elasticity  having  been  diminished — a  result 
which  never  happens."  (Wundt.)  He  arrives  at  the  conclusion  that  the 
elasticity  of  active  muscle  is  practically  the  same  as  that  of  muscle  in 
repose.  One  can  conceive  a  muscle  so  loaded  that  at  the  moment  of 
contraction  no  change  in  its  length  could  take  place,  because  the  energy 
tending  to  shorten  the  muscle,  that  is  its  contractile  power,  would  be 
exactly  equal  to  the  energy  tending  to  lengthen  it,  against  its  elastic  force. 
These  results  have  been  confirmed  by  the  research  of  Donders  and  Van 
Mansveldt,  conducted  upon  the  flexor  muscles  of  the  fore-arm  of  man. 
After  a  muscle  has  been  once  stretched  by  a  considerable  weight,  and 
the  weight  has  been  removed,  it  may  not  return  to  its  original  length 
for  days  or  weeks.  This  is  called  an  elastic  after  effect.  This  is  especially 
noticeable  after  the  use  of  very  heavy  weights.  To  recapitulate:  (1)  the 
elongation  of  muscle  is  within  certain  limits  proportional  to  the  weight ; 
(2)  the  modulus  of  elasticity  is  very  nearly  the  same  for  different  degrees 
of  contraction ;  and  (3)  fatigue  and  defective  niitrition  diminish 
elasticity.     (Roy.) 

According  to  Marey,  the  elasticity  of  muscle  favours  the  economical 
expenditure  of  muscular  work,  in  virtue  of  a  law  which  he  thus  formu- 
lates :  when  a  force  of  short  duration  is  employed  to  move  a  mass,  a 
more  useful  effect  is  obtained  when  it  acts  upon  this  mass  through  the 
intervention  of  an  elastic  body.^  The  feeble  elasticity  of  muscle  is  such 
as  to  oppose  very  little  resistance  to  antagonist  muscles,  and  when  the 
contraction  of  the  antagonist  ceases,  it  restores  the  muscle  to  its  natural 
length  without  loss  of  force. 

^  Marey,  Physiologie  Experimentah,  1875. 


400  THE  CONTRACTILE  TISSUES. 

In  the  li\'iiig  lieiiig-,  imiscles  are  more  or  less  stretched  between  their 
two  attachnients.  Thus  they  arc  in  a  state  of  tension  or  tonicity,  some- 
times termed  iniismhir  tonus,  it  may  be  by  the  contraction  of  antagonist 
muscles,  or  even  by  the  weight  of  parts  of  the  skeleton  or  of  soft  parts. 
When  a  muscle  is  divided  transversely,  or  its  tendon  is  cut,  it  therefore 
immediately  contracts,  and  the  two  parts  separate  to  some  extent  from 
one  another.  Thus  a  muscle,  even  at  rest,  is  in  a  favourable  condition  for 
producing  by  its  contraction  a  given  movement  without  loss  of  energy. 
A  muscle  is  always  taut,  never  in  a  state  of  looseness,  and  it  is  therefore 
ready  to  efficiently  exert  mechanical  force  the  moment  it  begins  to  con- 
tract. The  sphincters  are  the  only  muscles  which,  during  repose,  do 
not  appear  to  be  stretched.  Their  tonicity  operates  only  when  they  are 
dilated. 

Various  controversies  have  arisen  upon  the  question  as  to  whether  or 
not  muscular  tonus  is  under  the  influence  of  the  nervous  system.  Brond- 
geest  divided  the  spinal  cord  of  a  frog  below  the  medulla  ohlongata,  and 
then  divided  the  nerves  of  the  leg  on  one  side ;  on  fixing  the  frog  firmly 
against  a  board,  he  found  that  the  muscles  of  the  leg  on  the  side  of  the  oper- 
ation were  loose  and  flaccid,  and  that  this  leg  was  longer  than  the  other 
leg.  He  therefore  concluded  that  the  spinal  cord  furnished  the  muscles, 
especially  the  flexors,  with  permanent  innervation.  Heidenhain,  on  the 
other  hand,  found  that  when  a  muscle  is  stretched  by  a  weight,  it  does 
not  elongate  after  section  of  the  nerve  supplying  it.  The  probability  is 
that  both  innervation  and  the  circulation  of  the  blood  have  a  certain 
influence  upon  muscular  tonicity,  by  affecting  the  nutrition  of  the  tissue. 

Chap.  VI. -MUSCULAR  IRRITABILITY. 

By  this  phi'ase  is  meant  the  property  which  living  muscle  possesses 
of  responding  to  a  stimulus,  the  visible  indication  of  a  response  being  a 
change  of  form  or  a  contraction.  The  term  excitahility  is  sometimes 
employed  to  denote  the  same  fact.  Irritability  is  a  property  inherent 
in  the  muscular  fibre,  a  doctrine  first  clearly  enunciated  by  Haller. 
The  best  experimental  proof  of  this  fact  was  first  given  by  Claude 
Bernard.  He  showed  that  if  we  poison  an  animal  with  curare,  stimu- 
lation of  the  motor  nerves  produces  no  eff"ect,  Avhile  the  direct  excitation 
of  the  muscle  substance  is  at  once  folloAved  by  a  contraction.  It  might 
be  objected  to  this  experiment  that  the  persistence  of  irritability  may 
depend  on  the  integrity  of  the  motor  end-plates  of  the  muscle, 
which  may  not  have  been  affected  by  the  poison;  but,  as  was  first 
shown  by  Kiihne,  muscular  fibres  exist  in  which  he  could  not 
find   motor  end-plates,    but   these   were   still    capable   of    contracting 


MUSCULAR  IRRITABILITY. 


401 


on  the  application  of  a  stimulus.  Bernard's  experiment  may  be  readily 
shown  if  we  ligature  the  sciatic  artery  in  the  leg  of  a  frog  and  then 
inject  a  minute  dose  of  a  solution  of  woorari  or  curare  ^ 
under  the  skin  of  the  back  by  means  of  a  hypo- 
dermic syringe,  such  as  is  shown  in  Fig.  260.  The 
ligature  round  the  artery  prevents  the  poison  from 
entering  the  tissues  of  the  leg  supplied  by  it.  Curare 
is  known  to  have  the  effect  of  paralyzing  the  motor  end- 
plates  in  muscles.  (See  p.  358.)  After  sufficient  time 
has  been  allowed  to  elapse  for  the  poison  to  act,  an 
indication  of  which  may  be  seen  in  the  animal  being 
completely  paralyzed,  two  ordinary  nerve-muscle  pre- 
parations are  made,  similar  to  that  shown  in  Fig.  261, 
the  one  from  the  poisoned  and  the  other  from  the 
unpoisoned  limb.  Each  limb  is  connected  with  a  useful 
apparatus  for  demonstration,  shown  in  Fig.  262,  termed 
a  muscle  telegraph.  The  two  telegraphs  are  placed  close 
beside  each  other,  so  as  to  make  it  possible  to  stretch 
the  two  sciatic  nerves  across  Du  Bois-Reymond's 
platinum  electrodes.  Fig.  229,  p.  379,  and  arrangements 
are  made  by  the  use  of  Pohl's  commutator  (Fig.  228,  p. 

378),  so  that  an  induction  shock  may  be  transmitted  Fig.  260.— Hypoder- 
mic  syringe.     Ob- 

either   to   the   two   muscles   or   to   the   two  nerves   at  serve    the    piston 
pleasure.     It  will  then  be  found  that  when  both  nerves 
are  stimulated  only  the  muscle  of  the  limb  that  received  no  poison  will 
contract,  but,  on  the  other  hand,  when  the  shock  is  sent  through  both 
muscles,  both   contract,  that  is  to 
say,  the  muscle  in  which  all  the  nerve- 
endings   have   been    paralyzed    by 
curare    has    still    the    property   of 
irritability.     It  may  also  be  shown 
that  the  muscles  of  the  limb  that 
received  no  poison  will  respond  to  a 
feebler  induction  shock   than   that 
necessary  to  excite  the  muscles  of 
the  poisoned  limb.      This   is  due. 


^jr 


Fig.  261. — Nerve-muscle  Preparation. 
F,  femur ;  N,  nerve ;  /,  aperture  for 
hook. 


^  Curare,  curara,  ourali,  woorali,  woorari,  urari,  tiguDas,  or  Indian  arrow- pois  on 
is  the  inspissated  juice  of  strychnos  Crevauxi  (?).  It  contains  an  alkaloid  named 
curarin.  A  dose  of  2  to  5  m.gms.  is  sufi&cient  for  the  experiment  above  de- 
scribed. An  extract  or  solution  is  made  by  dissolving  it  in  water  with  the  aid  of 
a  few  drops  of  alcohol  and  of  glycerine.  The  strength  of  the  solution  should  be 
1  per  cent. 

I.  2C 


402 


THE  CONTRA  CTILE  TISSUES. 


as  was  first  shown  by  Rosenthal,  to  the  nerve-endings  in  the  sound  liml) 
being  more  excitajile  than  the  muscle  substance,  so  that  a  feeble  shock 
sent  through  the  muscles  of  both  limbs  may  excite  only  the  sound  liml) 


by  irritating  its  nerve-endings,  but  when  the  shock  is  made  stronger, 
then  it  is  sufficient  to  excite  the  protoplasm  of  both  muscles,  and  then 
both  contract. 


MUSCULAR  IRRITABILITY.  408 

The  view  of  the  inherent  irritability  of  muscle  is  also  supported  by 
TQany  other  facts.  Thus  sulphocyanide  of  potassium  abolishes  irrita- 
bility without  aifecting  the  activity  of  the  nerve,  and  carbolic  acid  and 
ammonia,  directly  applied,  excite  the  muscle  substance  without  irritating 
the  nerve  ;  electric  currents  of  very  short  duration  may  excite  the  nerve 
without  exciting  the  muscle;  and  irritability  may  last  several  weeks  after 
section  of  the  motor  nerves,  while  the  excitability  of  the  nerves  is  lost  in 
^bout  four  days.  Dr.  John  Reid  showed  that  after  having  exhausted 
the  nerve  supplying  a  muscle  by  repeated  shocks  so  that  the  muscle  no 
longer  responded  to  the  nerve,  it  was  still  possible  to  cause  the  muscle 
to  contract  by  its  direct  stimulation.  To  this  experiment  there  is  the 
objection  that  the  encl-plates  may  not  have  been  completely  exhausted 
by  the  shocks  applied  to  the  nerve.  Finally,  irritability  may  be 
observed  in  structures  having  no  nerves  and  consisting  only  of  proto- 
plasm, such  as  the  contractile  tissues  of  plants,  the  bodies  of  many  of 
the  protozoa  and  coelenterata,  the  hearts  of  many  invertebrates,  the 
foetal  heart,  the  colourless  blood  corjDUScles,  spermatozoids,  and  cilia. 
When  we  remember  that  the  essential  constituent  of  muscle  is  proto- 
plasm, one  of  the  prominent  phenomena  of  which  is  its  capability  of 
responding  to  a  stimulus,  it  requires  little  evidence  to  convince  us  of 
the  truth  of  Haller's  doctrine. 

As  already  explained  at  p.  29,  in  discussing  the  relations  of  energy 
to  living  structures,  stimuli  are  to  be  regarded  as  liberators  of  energy. 
The  protoplasm  of  muscle  is  not  to  be  regarded  as  endowed  with  a 
special  property  in  the  sense  of  a  metaphysical  entity,  but  the  use  of 
the  word  irritability  merely  indicates  that  muscle  is  a  substance  in 
which  molecular  disturbances  may  be  started  by  various  kinds  of 
.stimuli.  Irritability  is  simply  the  term  expressing  this  condition. 
With  this  explanation  of  what  is  meant  by  irritability  and  by  a  stimulus, 
we  now  proceed  to  state  that  muscular  irritability  is  excited  by  the 
.■stimulus  propagated  along  a  nerve,  or  by  nervous  action.  This  is  the 
normal  stimulus ;  but  muscle  may  also  be  stimulated  mechanically  by 
tension  or  stretching,  by  percussion,  or  by  pricking,  etc. ;  by  the 
miction  of  electricity  and  heat;  or  chemically  by  such  agents  as 
ice-cold  water,  weak  solutions  of  metallic  salts,  dilute  acids,  alkaline 
•chlorides,  ammonia,  etc.  The  effects  of  these  agents  will  be  afterwards 
'discussed. 

Muscular  irritability  may  be  increased  or  conserved  for  a  considerable 
time  by  the  following  conditions  : — (1)  by  an  afflux  of  blood  :  if  the 
lumbar  nerves  of  a  frog  are  divided  on  one  side,  the  capillaries  become 
•dilated  from  paralysis  of  the  vaso-motor  nerves,  and  the  irritability  of 
the  muscles  is  then  greater  than  on  the  uninjured  side ;  section  through 


404  THE  CONTRACTILE  TISSUES. 

one  half  of  the  medulla  oblongata  and  of  the  corpora  higemina  is  followed 
by  hypersemia,  or  increase  of  l)lood,  and  increase  of  irritability  in  one 
half  of  the  body  ;  (2)  by  rest,  that  is  to  say,  after  a  muscle  has  become 
exhausted  so  that  its  irritability  has  been  much  reduced,  it  will  recover- 
after  a  period  of  inactivity  ;  (3)  by  the  presence  of  oxygen ;  muscles- 
retaining  their  irritability  longer  in  oxygen  than  in  ordinary  air,  and 
still  longer  than  in  air  deprived  of  its  oxygen ;  the  injection  of  oxygen- 
ated blood  into  a  limb  entirely  separated  from  the  body  maintains- 
irritability  for  a  considerable  time ;  (4)  by  the  effect  of  gentle  stimulation,, 
so  that  -while  a  muscle  may  not  respond  to  the  first  or  second  of  a 
series  of  feeble  stimulations,  it  may  contract  Avith  the  third  or  fourth,. 
and  then  there  may  be  a  number  of  contractions  greater  than  the  first 
one,  sho-wing  that  the  irritability  has  become  increased  ;  (5)  by  the  action 
of  certain  substances,  such  as  theine  and  veratrin  ;  and  (6)  by  the  passage- 
through  the  muscle  in  a  longitudinal  direction  of  a  very  feeble  con- 
tinuous current  of  electricity. 

Irritability  is  diminished  or  destroyed  by  (1)  arrest  of  the  circulation  ,-. 
(2)  fatigue  ;  (3)  a  temperature  considerably  above  or  belo-vv  the  mean 
temperature  of  the  muscle,  which  varies  in  different  species  of  animals ;. 
(4)  the  presence  in  excessive  quantity  in  the  muscle  of  such  substances 
as  carbonic  acid,  lactic  acid,  phosphate  of  lime,  and  certain  alkaloids. 
It  is  said  that  muscular  irritability  is  almost  instantaneously  destroyed 
by  large  doses  of  sulphocyanide  of  potassium,  all  the  salts  of  potash,, 
the  bile,  emetine,  upas  antiar,  etc. 

After  division  of  the  nerves  supplying  it,  and  Avhen  the  circulation  is- 
cut  off,  the  irritability  of  a  muscle,  as  a  rule,  diminishes  during  the  first 
four  or  five  days.  Then  folloAvs  a  period  of  several  weeks  (from  6  to  8) 
in  the  human  being,  during  which  there  is  an  increased  irritability  to- 
mechanical  stimulation  and  to  the  opening  and  closing  shocks  of  a 
constant  voltaic  current,  while  induction  shocks  from  an  inductorium 
have  little  or  no  effect.  This  stage  merges  into  one  in  Avhich  the 
irritability  slowly  diminishes  imtil  it  may  entirely  disappear. 

Irritability  disappears  more  quickly  after  death  from  warm-blooded 
than  from  cold-blooded  muscles.  The  muscles  of  many  amphibia,  if 
kept  in  a  cold  place,  Avill  remain  excitable  for  eight  or  ten  days. 
According  to  Brown-S^quard,  irritability  lasted  in  the  muscles  of  the^ 
following  animals  for  the  following  periods — 

Eabbit, 8^  hours. 

Sheep, 10-^      „ 

Dog, Ill      „ 

Cat, 12i      „ 

Frog, 24  to  40        „ 


MUSCULAR  IRRITABILITY.  405 

About  1|  to  3  hours  is  the  average  time  during  which  most  of  the 
muscles  of  warm-blooded  animals  remain  irritable.  In  man  it  has  been 
observed  to  last  for  even  so  long  a  period  as  26  hours  after  death,  but 
in  most  cases  it  disappears  in  the  course  of  five  or  six  hours.  The 
muscle  of  the  heart  remains  longer  irritable  than  any  other  muscular 
structure,  continuing,  even  in  the  human  being,  for  two  hours.  It 
vanishes  quickly  from  the  muscles  of  persons  who  have  died  from 
exhaustive  diseases,  but  it  may  last  a  long  time  in  well  nourished 
muscles. 


€hap.  VII.— general  phenomena  OF  MUSCULAR  CONTRACTION. 

When  a  muscle,  say  the  gastrocnemius,  removed  from  the  leg  of  a 
recently  killed  frog,  is  caused  to  contract,  it  assumes  the  form  of  a 
globular  mass  which  is  about  one  third  of  the  total  primitive  length  of 
the  muscle.  In  the  living  body,  however,  the  shortening  is  never  so 
great,  as  the  two  ends  are  stretched  by  the  elastic  force  of  the  antagonist 
muscles  and  the  resistance  at  the  points  of  insertion.  The  amount  of 
•contraction  of  each  muscle  depends  upon  its  length,  and,  for  a  given 
muscle,  the  shortening  increases  with  the  intensity  of  the  stimulus,  and 
diminishes  with  the  fatigue  of  the  muscle.  With  the  same  strength  of 
stimulus,  and  supposing  the  muscle  not  to  be  fatigued,  an  elevation  of 
the  temperature  up  to  33°  C.  increases  the  amount  of  contraction. 
Above  this  point,  the  amount  of  contraction  diminishes. 

When  a  muscle  contracts,  the  absolute  volume  diminishes  very  slightly, 
so  that  the  specific  gravity  of  the  muscle  is  1062,  instead  of  1061,  in  the 
inactive  state.  This  may  be  demonstrated  by  placing  the  muscle  in  a 
small  bottle  filled  with  water,  through  the  walls  of  which  two  fine 
platinum  wires  are  fused  for  the  purpose  of  conveying  an  electric 
stimulus  to  the  muscle.  The  stopper  of  the  bottle  is  drawn  out  into  a 
long  capillary  tube,  in  which  the  fluid  in  the  bottle  ascends.  It  will 
then  be  found  that,  on  causing  the  muscle  to  contract,  the  fluid  in  the 
capillary  tube,  when  examined  with  a  microscope,  descends  very 
slightly — that  is  to  say,  there  is  a  diminution  in  volume,  by  about 
the  1000th  part. 

Another  mode  of  observing  muscular  contraction  is  to  examine  under 
the  microscope,  with  a  magnifying  power  of  300  diameters,  a  living 
muscular  fibre  removed  from  the  leg  of  an  insect.  On  stimulating  the 
fibre  at  one  end,  an  undulation  will  be  observed  to  travel  along  the 
whole  length  of  the  fibre,  and  the  transverse  strise  approach  each  other. 
This  phenomenon  will  be  best  observed  when  the  muscle  is  slightly 
stretched.     On  adapting  the  polarizing  apparatus  to  the  microscope,  it 


406  THE  CONTRACTILE  TISSUES. 

will  be  observed,  as  has  been  already  stated,  that  the  anisotropic  portion,, 
or  sarcous  element,  is  the  seat  of  the  contraction  (Fig.  166,  p.  311). 
From  a  careful  observation  of  the  appearances  seen  with  polarized  light,, 
Engelmann  is  of  opinion  that,  during  contraction,  the  singly  refractive 
portions  shrink,  Avhile  the  doubh'  refractive  become  larger.  I  haA^e 
been  unable  to  observe  this  phenomenon,  Ijut  the  movement  seemed  tO' 
me  to  consist  in  a  change  of  form  of  the  anisotropic  portion.  During 
contraction,  the  latter  became  l)roader  in  proportion  to  its  shortening. 
As  to  the  notion  that  at  any  period  the  isotropic  more  fluid  part  pene- 
trates the  anisotropic  portion,  I  have  seen  nothing  to  lend  it  any  support- 

A. — Phases  of  a  Single  Contractiox  or  Twitch. 

The  phenomena  already  mentioned  may  be  noticed  by  the  unaided 
eye  or  by  the  use  of  the  microscope,  but  as  they  do  not  include  all  the 
phases  of  muscular  contraction,  many  of  which  are  of  very  short  dura- 
tion, recourse  must  now  be  had  to  various  methods  of  accurate  experi- 
ment. These  are  conducted  with  the  aid  of  myographs,  by  which  a 
graphic  representation  of  the  curve  of  muscular  contraction  may  be 
obtained.  The  arrangement  of  the  apparatus  in  this  experiment  is- 
shown  in  Fig.  250,  p.  392.     (See  also  Fig.  251,  p.  393.) 

The  experiment  is  conducted  as  follows — The  gastrocnemius  muscle, 
the  contraction  of  Avhich  is  to  be  studied,  is  fixed  by  its  tendon  to  the- 
lever  of  the  myograjih  (c),  and  the  nerve  is  brought  into  contact  with 
the  electrodes ;  the  recording  cylinder  (ci)  is  then  allowed  to  rotate,  and 
when  it  has  attained  sufiicient  A-elocity,  the  ke}^  (/)  in  the  primary 
circuit  of  the  coil  (e)  is  opened ;  a  single  induction  shock  is  thus  trans- 
mitted to  the  nerve,  which  causes  the  muscle  to  contract  and  to  describe,, 
by  moving  the  lever  of  the  myograph,  the  curve  a  c  d  c,  in  Fig.  263. 

On  analyzing  this  curve,  we  find  it  to  be  composed  of  three  unequal 
periods — 

(a)  Suppose  the  muscle  has  received  the  shock  at  h,  there  is  a  short 
period  represented  by  the  line  from  h  to  c,  in  Avhich  no  contraction 
occurs.  This  time,  usually  about  the  ^ho  ^f  a  second,  is  called  the 
IJeriocl  of  latent  stimulation.  Its  commencement  and  termination  are- 
easily  registered  if  we  interpose  in  the  primary  circuit  a  signalling 
apparatus,  which  would  draw  on  the  cylinder  the  line  f  g  h  ik;  while 
the  time  is  recorded  by  a  chronographic  tracing  /  m.  It  is  during  this 
period,  short  as  it  is,  that  molecular  changes  occur  in  the  muscle  jire- 
paratory  to  contraction,  and,  as  \n\\  afterwards  be  seen,  an  important 
electrical  phenomenon,  the  negative  variation  of  the  muscle  current 
also  takes  place.  The  latent  period  in  human  muscles,  and  probably 
also  in  the  muscles  of  mammalia  in  general,  is  shortei',  varying  from  '004 


PHENOMENA  OF  MUSCULAR  CONTRACTION. 


407 


to  '01  of  a  second.  The  application  of  heat  and  an  increase  in  the 
strength  of  the  stimulus  increase,  and  an  increasing  weight,  cooling, 
and  fatigue  diminish,  the  length  of  the  period.  The  period  is  longer  in 
red  than  in  pale  muscles.  "V^Tien  metabolism  in  the  muscle  is  interfered 
■with,  either  by  changes  in  the  muscle  substance  itself,  or  by  changes  in 
its  relation  to  the  stimulus  of  the  nerve,  the  latent  period  is  increased. 
Thus  it  is  lengthened  in  paralysis  agitans,  progressive  locomotor  ataxia, 
muscular  atrophy,  and  in  cases  of  degeneration  of  the  spinal  cord  after 
apoplexy.  It  is  said  to  be  shortened  in  senile  chorea  and  tabes 
dorsalis.     (For  results  obtained  by  Yeo  and  Cash,  see  Appendix  III.) 

(b)  A  second  period,  corresponding  to  the  contraction  of  the  muscle, 
indicated  by  the  ascent  of  the  curve  c  d,  the  duration  of  Avhich  varies 
from  '03  to  "4  of  a  second.  A  fresh  active  miiscle  contracts  more  rapidly 
than  a  fatigued  one. 

d 


Fio.  263. — Curve  of  a  muscular  contraction,  produced  by  a  single 
induction  shock,  n  h  cd  e,  line  drawn  by  the  lever  of  [he  myograph  ; 
fg  hik,  line  drav?n  by  electric  signalling  apparatus  ;  I  m,  chronograpli 
registering  100  vibrations  per  second. 

(c)  A  third  period  of  relaxation,  represented  by  the  descent  of  the 
curve  d  e,  in  which  the  muscle  returns  to  its  primitive  length ;  this 
period  is  usually  shorter  than  the  second,  Imt  in  the  tracing  shown  in 
Fig.  263  it  is  longer,  because  the  strength  of  the  stimulus  employed 
was  rather  strong.  The  descending  curve  should  have  reached  the 
level  of  the  line  a  c,  about  the  position  of  the  asterisk  (*).  In  most 
cases,  one  or  two  short  vibrations  may  be  seen  after  the  end  of  the 
relaxation  of  the  muscle.  These  have  been  termed  residual  contractions, 
or  after  contractions.  They  are  due  to  the  elasticity  of  the  muscle,  and 
are  consequently  most  pronounced  when  the  muscle  has  made  a  strong 
contraction  and  has  lifted  only  a  small  weight.  They  are  often  seen  in 
tracings  taken  with  the  rapidly  moving  pendulum  myograph  (Fig.  264). 
On  examining  the  curve,  we  see  that  the  height  of  the  line  (/  i, 
indicates  the  amount  of  contraction. 


408 


THE  CONTRACTILE  TISSUES. 


The  curve  of  a  single  muscular  coutraction  may  also  be  recorded  on  the  pendulum 

myograph,  shown  in  Fig.  264. 
It  consists  of  a  stout  board  A  A 
fixed  to  the  wall  of  the  labora- 
tory.     This    carries   a  strong 
rectangular  metal  frame  C  C  C, 
having  poised  on  it,  on  friction 
rollers,  at  a  and  at  the  other 
end,  an  axle  E  E  E  from  which 
is  suspended  by  stout  double 
rods  FFFF,  a  pair  of  heavy 
glass  plates  f/  g  and  rj '  g ',  which 
are  smoked  in  the  flame  of  a 
paraffin  lamp  before  a  tracing 
is  taken.     These  constitute  the 
bob  of  the  pendulum,  and  to 
maintain  the  centre  of  gravity 
;      of  the  system  at  the  same  place, 
>      even  although  for  convenience 
\      in  taking  a  tracing  the  plate  fj  g 
\      may  be  moved  up  or  down  by 
f      a  rack  and  pinion  movement  h  c, 
I      the  plate  g' g',  which  is  of  the 
;      same  weight  as  g  g,   may  be 
moved  in  the  reverse  direction. 
I      When  used,  the  pendulum  is 
1)      pulled  to  the  left  towards  ff, 
■>      and  it  is  held  in  position  by  the 
j      spring  catch  e ',  which  is  turned 
I      outwards.      On  the  pendulum 
I      making   a   swing,  it  is  caught 
'      at  the   extreme    limit    of    its 
;      swing  by  the  catch  e ',  which  is 
I      also   turned    outwards.       The 
1      under    surface    of    the    frame 
carrying    the    glass-plates  has 
two  little  projections//',  each 
moving   on   a   delicate    hinge, 
and  when  the  pendulum  swings 
across,  these  strike  the  arm  b 
of   a  break-mechanism   placed 
immediately  below  //'  in  the 
position  occupied  by  these  in 
Fig.  264.     This  break-mechan- 
ism is  shown  in  Fig.  265.     In 
newer  forms  of  the  myograph 
than  that  shown  in  Fig.   264, 
the  break-mechanism  slides  on 
a  horizontal  bar,  so  that  it  can 
be  brought  into  operation  at  any 


PHENOMENA  OF  MUSCULAR  CONTRACTION. 


409 


-point  in  tlie  swing  of  the  pendulum.  The  break-tnechan- 
ism  is  simply  a  little  arm  6,  Fig.  265,  which  is  knocked 
aside  by  //'  in  Fig.  264.  The  primary  circuit  of 
an  inductorium  passes  from  the  binding  screw  d,  Fig. 
265,  through  pillar  rj  to  a,  thence  through  h  (when 
in  contact  with  a),  and  then  back  to  the  battery,  and 
J  is  insulated  from  the  rest  of  the  instriiment.  When 
b  and  a  are  in  contact,  the  primary  circuit  is  formed, 
but  when  b  is  knocked  away  from  a  by  ^  in  Fig.  264, 
it  is  opened.  The  opening  shock  of  the  inductorium 
is  sent  to  the  nerve-muscle  preparation  connected  with 
a  myograph  placed  in  front  of  the  front  glass- 
plate,  the  muscle  contracts,  and  a  curve  is  described 
on  the  glass-plate,  such  as  is  shown  in  Fig.  266.  As 
-t\as  instrument  has  been  of  great  service  in  measuring 


Fig.  265. — Break-Apparatus  of  the 
Pendulum  Myograph. 


the  rate  of  the  transmission  of  the  nerve  current,  it 
will  be  further  described  when  we  consider  the  func- 
tions of  nerve  in  Vol.  II.  The  pendulum  makes  a 
•complete  swing  from  one  catch  e.  Fig.  264,  to  the  other 
•catch  e'  in  one  second,  and  the  time  of  any  part  of  the 
■swing  may  be  recorded  by  means  of  a  chrono- 
graphic  tracing,  as  shown  in  Fig.  266. 

The  pendulum  myograph  is  usually  provided  with 
two  "break"  mechanisms,  similar  to  that  shown  in  Fig. 
"265,  but  so  arranged  that  the  one  is  opened  by  the  swing 
of  the  pendulum  a  little  sooner  than  the  other.  Thus, 
by  having  two  circuits,  a  nerve  may  be  stimulated  by 
one  induction  shock,  and  then  by  another  happening 
the  x^th  of  a  second  later,  and  the  muscle -curve  may 
then  be  similar  to  that  shown  in  Fig.  276,  p.  416.  The 
instrument  has  also  been  used  by  Burdon-Sanderson  as 
a  rheotome,  that  is  an  instrument  for  opening  and 
Kilosing  two  independent  circuits,  at  very  short  periods 


3  Y 


41() 


THE  CONTRACTILE  TISSUEiS. 


of  tiiiic.^      Thus   the   time    relations  of   various   electrical   phenomena    may   be 
investigated. 

For  purposes  of  comparison,  it  is  often    important  to  obtain  a  series 
of  ciirves  in  juxtaposition.     We  may  get  this  by  using  the  travelling 


stage  of  Marey  (Fig.  267),  so  that  the  shock  is  sent  to  the  muscle  a 
little  later  in  each  revolution  of  the  cylinder. 

^  Burden-Sanderson.       On  the  electromotive  properties  of  the  leaf  of  Dion£ea. 
Phil.  Trans.  Part  I.  18S2. 


PHENOMENA  OF  MUSCULAR  CONTRACTION. 


411 


It  can  easily  be  arranged  that  the  recording  cylinder  carries  a  Avire 
attached  to  its  axle,  through  which  the  current  passes  when  the  vnxQ 
dips  with  each  revolution  into  a  cup  of  mercury  interposed  in  the 
circuit      Thus  each  revolution  of  the  cylinder  makes  and  breaks  the 


Fig.  268. — Arraugement  for  recording  consecutive  contractions  of  a  frog's  gastrocnemius 
muscle,  each  contraction  occurring  a  little  later  in  time  th;iu  the  one  immediately  jire- 
ceding  it. 

current  passing  through  the  primary  coil  of  an  inductorium,  either  at 
the  same  moment,  or  a  little  later,  mth  each  successive  contact.  Thu^ 
arrangement  for  the  latter  purpose  is  shown  in  Fig.  268. 

By  this  method,  tracings  may  be  obtained,  such  as  those  shown  in 


Fig.  269. — Tracings  of  muscular  contractions  produced  by  successive  single 
induction  shocks,  to  be  read  from  left  to  right,  thus — a,  b,  c. 

Fig.  269,  and  Fig.  283,  p.  429,  an  insj^ection  of  which  at  once  elicits- 
facts  of  physiological  interest. 


412  THE  CONTRACTILE  TISSUES. 

The  duration  of  muscular  contraction  varies  in  different  species  of 
animals  ;  it  is  very  short  in  birds,  somewhat  longer  in  mammals  and  fishes, 
and  still  longer  in  reptiles.  The  amplitude  of  the  curve,  indicating  the 
ammint  of  nmscidar  contraction,  increases  Avith  increase  of  the  stimulus, 
at  first  rapidly,  then  more  and  more  slowly,  and  Avhen  a  maximum  is 
reached  it  remains  constant,  as  indicated  by  the  amplitude  of  the  curve 
remaining  the  same.  Fatigue  diminishes  the  amplitude  and  increases 
the  duration  of  the  contraction,  as  seen  in  Fig.  283.  Stoppage  of  the 
■circulation  and  cold  has  the  same,  whilst  the  gentle  application  of  heat 
has  the  reverse,  eff'ect.  The  duration  of  muscular  contraction  is  in- 
creased in  diabetes,  jaundice,  cerebral  hemiplegia,  and  in  some  cases  of 
sclerosis  of  the  spinal  cord. 

The  rapidifAj  of  muscular  contractions  is  very  great  in  man  and  in  the 
mammalia.  Thus,  Landois  found  that  each  contraction  of  the  muscles 
in  writing  the  letter  n  lasted  only  -0564  of  a  second.  A  striking  illus- 
tration of  the  rapidity  of  muscular  contractions  is  seen  in  the  rapid 
movements  of  the  fingers  of  a  violinist  or  pianoforte  player,  or  in  the 
rapid  movements  of  the  muscles  of  the  larynx  when  a  singer  trills  in  the 
execution  of  vocal  music. 

If  a  fatigued  muscle  has  been  strongly  stimulated,  it  may  contract, 
but  it  may  not  immediately  relax  when  the  stimulus  has  ceased  to  act, 
so  that  it  may  require  a  weight  to  stretch  it  to  its  original  length.  This 
condition  of  temporary  contraction  is  called  the  contraction  remainder. 
It  may  be  seen  to  some  extent  in  muscles  not  greatly  fatigued. 

B. — Pkopagation  of  a  Wave  of  Contraction, 

When  a  living  muscle  is  stimulated,  it  not  only  contracts,  but  becomes 
thicker.  The  curve  of  the  movement  of  thickening  has  been  found  to  be 
generally  the  same  as  that  of  contraction.  This  may  be  shown  by  the 
arrana;ement  seen  in  Fia;.  270. 


Fig.  270.— Diagram  showing  apparatus  for  recording  the  curve 
of  thickening,  a  b,  Two  light  levers  joined  at  the  point  on  the 
right  and  resting  on  the  muscle,  c  d.  The  muscle  is  caused  to 
contract  by  sending  an  induction  shock  through  it.  The  trac- 
ing is  recorded  and  compared  with  that  obtained  by  a  myograph. 

As  has  been  already  mentioned,  if  a  stimulus  is  applied  to  one  end  of 
a  living  muscular  fibre,  a  wave  is  seen  to  propagate  itself  towards  the 
other  end.     This  has  been  termed  the  ivctve  of  contraction,  and  Marey  has 


PHENOMENA  OF  MUSCULAR  CONTRACTION. 


41.5 


measured  its  rapidity  by  grasping  it  at  two  places  with  instruments- 
called  myographic  pincers  (Fig.  271,  1,  2).  Each  of  these  is  connected 
with  a  transmitting  tambour.  The  recording  tambours,  1',  2',  trace  the 
curves  on  a  cylinder.     When  we  stimulate  one  of  the  ends  of  th& 


Fig.   271. — Arrangement  for  tracing  the  •wave  of  muscular  contraction.      The 
muscle  is  diagrammatic. 

muscle,  the  thickening  which  accompanies  the  contraction,  as  it  passes- 
from  one  end  to  the  other,  acts  through  the  pincers  upon  the  two- 
receiving  tambours  successively,  and  a  tracing  is  obtained  such  as  is 
seen  in  Fig.  272. 

It  will  be  seen  that  the  two  curves  do  not  coincide,  and  the  distance 
between  their  summits  gives  the  rapidity  of  propagation  of  the  muscular- 
wave,  which   is  from  1  to  3  metres  per  second.      The  wave  ""in  the^ 


Fig.  272. — Tracing  of  the  propagation  of  the  muscular  wave.     Chrono- 
graphic  tracing,  100  vibrations  per  second  underneath.    (Marey.) 

muscle  of  the  heart  travels  slowly,  being  only  at  the  rate  of  10  to  15^' 
mm.  per  second,  and  in  the  muscles  of  the  lobster  it  progresses  at  the 
speed  of  1  metre  per  second.  In  living  human  muscle  it  is  very  rapid, 
10  to  13  metres  per  second — so  rapid  that  some  have  denied  its  exist- 
ence. The  wave-length  has  been  estimated  at  only  206  to  380  mm^ 
Cold  diminishes  the  rate,  as  shown  in  Fig.  273. 


414 


THE  CONTRACTILE  TISSUES. 


Fatigue,  the  tendency  to  coaguLition  of  the  myosin  so  as  to  i)roduce 
ji(j(yr  mortis,  veratrin,  and  sulphocyanide  of  potassium  also  dela}^  the  pro- 
_gression  of  the  Avave.  The  wave  of  contraction  excited  in  a  muscular 
fibre  is  limited  to  it  alone,  and  is  not  transmitted  to  neighbouring  iibres. 
A  muscle  contracts  as  a  Avhole  only  Avhen  all  its  fibres  have  l)een  simul- 
taneously excited.  When  the  nerve  stimulus  acts,  as  there  is  a  nerve 
fibre  for  each  muscular  fibre,  and  as  the  motor  end-plate  is  near  the 


Fio.  273. — Curves  showing  the  rapidity  of  the  transmission  of  the  wave  of  contraction 
in  the  muscle  of  a  rabbit.  A,  muscle  in  normal  condition  ;  B,  when  the  muscle  was 
cooled  by  ice.     Observe  that  in  B  the  wave  has  travelled  more  slowly. 

centre  of  the  fibre,  a  wave  of  contraction  proceeds  to  each  end  of  the 
fibre  from  the  end-plate.  Each  fibre  is  from  30  to  40  mm.  in  length,  so 
that  even  with  this  comparatively  short  length  it  can  scarcely  be  said  to 
contract  instantaneously  as  a  Avhole.  Practically,  a  muscle  contracts  as 
u  whole  when  it  receives  the  nerve  stimulus,  but  in  many  muscles,  and 
in  long  muscles  especially,  the  distance  of  individual  muscular  fibres 
from  the  main  nerve  trunk  will  vary  so  that  they  will  not  receive  the 
nerve  stimulus  precisely  at  the  same  instant. 


Chap.  VIII.— THE  GENESIS  OF  TETANUS. 

If  a  rapid  series  of  induction  shocks  be  sent  to  the  muscle  of  a  frog 
from  Du  Bois-Reymond's  inductorium,  seen  in  Fig.  222,  the  muscle  will 
l)ass  into  a  state  of  strong  contraction,  in  which  it  will  remain  a  consider- 
able time,  so  long  as  induction  shocks  are  transmitted  to  it.  This 
.«tate  of  strong  contraction  is  termed  tetanus  or  cramp,  and  is  quite 
different  in  character  from  the  short  contraction  caused  by  a  single 
shock,  which  we  have  termed  a  twitch.  In  the  first  place,  it  may  be 
•observed  that  the  shocks  sent  by  the  apparatus,  when  the  primary 
•circuit  is  automatically  closed  and  opened,  may  be  regarded  as  instan- 
taneous excitations.  AVhen  excitations,  by  induction  shocks,  amount 
in  number  to  three  or  four  per  second,  the  muscle  contracts  more 
strongly,  and  the  contraction  continues  for  a  longer  time  than  if  the 
muscle  had  received  a  single  shock  of  the  same  intensit3\     The  height 


THE  GENESIS  OF  TETANUS.  415 

of  a  contraction  caused  by  a  single  shock  is  usually  from  a  third  to  a 
half  that  caused  by  a  rapid  series  of  shocks,  or  tetanus.  We  may  readily 
make  this  observation  by  interrupting  the  current  of  the  induction 
coil  by  means  of  a  metronome  or  by  a  vibrating  spring,  so  that  the  num- 
ber of  shocks  sent  per  second  may  be  varied  at  pleasure.  It  will  then 
be  found  that  the  opening  shock  is  more  powerful,  as  shown  by  the 
amount  of  muscular  contraction,  than  the  closing  shock,  and  an  explana- 
tion of  this  phenomenon  has  already  been  given  (p.  374).  When  the 
shocks  succeed  each  other  regularly,  at  the  rate  of  about  fifteen  per 
second,  and  in  such  a  way  that  the  duration  of  the  interruption  is  short 
compared  with  the  duration  of  the  shock,  the  muscle  remains  persist- 
ently contracted.  The  phases  of  this  state  of  permanent  contraction 
must  be  carefully  studied. 

When  a  muscle  is  stimulated  by  an  inductorium,  it  draws  a  curve  on 
the  smoked  surface  of  a  revolving  cylinder  which  is  different  in  character 
from  the  curve  produced  by  a  single  shock,  described  in  the  last  chapter 
(Figs.  263  and  266).     The  curve  of  tetanus  is  shown  in  Fig.  274. 


Fio.  274.— Tetanus  produced  by  numerous  shocks  from  an  inductorium. 
The  interrupted  current  acted  a  little  before  a,  and  after  a  period  of 
latent  stimulation,  the  muscle  began  to  contract  so  that  the  lever  rises 
rapidly,  and  at  b  the  muscle  reaches  the  maximum  of  contraction.  The 
contraction  lasts  until  c,  when  the  current  is  shut  off  and  the  muscle 
slowly  relaxes. 

It  is  important  to  note  that  when  a  muscle  is  tetanized  by  an  induction 
current,  it  contracts  suddenly,  as  indicated  by  the  rapid  rise  of  the  lever, 
that  tetanus  is  a  condition  which  lasts  for  a  considerable  time,  and  that 
the  muscle  relaxes  slowly.  The  curves  in  Figs.  274  and  275  should  be 
compared. 

When  a  series  of  induction  shocks  is  more  slowly  transmitted  to 
the  muscle  in  contact  with  Marey's  myograph,  the  primary  current 
being  interrupted  by  a  metronome,  a  tracing  is  obtained,  as  in  Fig. 
275,  A  number  of  distinct  oscillations  will  be  observed  in  the  ascent 
of  the  curve.  Each  oscillation  is  somewhat  shorter  than  the  one 
immediately  preceding  it.  Three  cases  in  which  a  muscle  is  excited 
by  successive  shocks  present  themselves  for  consideration. 

1.  When  a  second  excitation  acts  after  the  termination  of  the  con- 
traction   occasioned    by   the    first,    it    produces    a    second    muscular 


410 


THE  CONTRACTILE  TISSUES. 


contraction  having  the  characters  of  the  first,  and  so  on,  as  regards 
successive  excitations,  until  the  muscle  becomes  fatigued. 

2.  If  the  second  excitation  acts  during  the  period  of  latent  stimulation 

following  the  first,  the 
shortening  is  not  greater 
than  for  one  excitation, 
and  the  curve  of  contrac- 
tion is  the  same. 

3.  If  the  second  excita- 
tion acts  during  the  two 
last  portions  of  the  pre- 
ceding contraction,  the 
shortening  corresponding 
to  the  second  excitation 
is  added  to  that  of  the 
first.  The  curve  thus  produced  is  seen  in  Fig.  276.  If  other  excita- 
tions quickly  follow,  each  capable  of  causing  a  partial  contraction, 
there  is  then  a  summation  of  the  effects  of  the  individual  excitations, 
and  a  state  of  permanent  contraction  or  tetanus  is  produced,  which 
is  the  fusion  of  the  partial  contractions  resulting  from  the  succes- 
sive  shocks.      This   is   well    illustrated    by   varying   the   number   of 


Fio.  275. — Tnicing  of  a  muscle  passing  into  a  tetanic 
state,  when  the  primary  current  of  an  inductorium  is 
rapidly  made  and  broken  by  a  metronome.  The  first 
shock  was  transmitted  to  the  nerve  at  a,  the  second  an 
instant  after  1,  the  third  an  instant  after  2,  and  so  on. 
It  will  be  observed  that  with  each  succeeding  shock  the 
muscle  becomes  shorter,  though  the  amount  of  shorten- 
ing at  each  shock  is  less. 


Pig.  276. — Tracing  of  a  double  muscle  curve.  While  the  muscle  was  en- 
gaged in  the  first  contraction  (whose  complete  course,  had  nothing  inter- 
vened, is  indicated  by  the  dotted  line),  a  second  induction  shock  was 
sent  to  it,  at  such  a  time  that  the  second  contraction  began  just  as  the 
first  was  beginning  to  decline.  a,b,  first  contraction;  c,d,  second  con- 
traction ;  /',  chronographic  tracing. 


excitations  transmitted  to  the  muscle.  Thus,  we  may  obtain  a 
curve  like  that  shown  in  Fig.  276  if  the  second  excitation  has  been 
sent  just  when  the  muscle  was  beginning  to  relax  from  the  effects 
of  the  first  excitation,  and  like  those  in  Figs.  275  and  277,  if  the  excit- 
ations followed  faster,  but  not  too  fast,  so  that  the  contractions  caused 
by  individual  excitations  appear  like  teeth  on  the  tracing,  and,  finally, 
like  Fig.  278,  when  the  excitations  follow  in  very  rapid  succession,  and 
individual  contractions  cannot  be  seen.  Tetanus  may  be  maintained 
for  a  considerable  time,  which  varies  according  to  the  degree  of  vitality 


THE  GENESIS  OF  TETANUS.  417 

of  the  muscle,  but  by  degrees  it  passes  off,  and  the  muscle  slowly 
returns  to  its  original  length,  under  the  influence  of  fatigue.  A  study 
of  the  genesis  of  tetanus  clearly  shows  that  it  is  a  condition  produced 
by  a  fusion  of  individual  contractions. 


Fig.  277. — Curve  showing  the  genesis  of  tetanus,  a  to  h,  individual  con- 
tractions ;  6  to  c,  muscle  now  tetanic,  but  wavy  line  still  indicating  indi- 
vidual contractions — the  slope  of  the  line  from  i  to  c  showing  that  the 
muscle  is  becoming  fatigued ;  c,  indicates  time  when  induction  shocks 
were  stopped  ;  c,  rf,  slow  relaxation  of  muscle. 

The  number  of  shocks  required  to  cause  tetanus  varies.  From  16  to 
SO^per  second  are  sufiicient  for  the  gastrocnemius  of  the  frog,  while  10 
per  second  may  cause  tetanus  of  the  frog's  hyoglossus  muscle.  Kro- 
necker  and  Stirling  found  incomplete  tetanus  of  the  red  muscles  of  the 
rabbit  to  be  caused  by  4  shocks  per  second,  while  10  shocks  per  second 
caused  complete  tetanus.  On  the  other  hand,  the  pale  required  over  20 
per  second.     It  is  curious  that,    according  to  Marey,  the  muscles  of 


Fig.  27S.— Curve  showing  genesis  of  tetanus,  a  to  6,  result  of  first  shock  ; 
then  observe  the  cumulative  effect  of  the  successive  shocks,  as  shown  by- 
gradual  ascent  of  curve  from  6  to  e  ;  stoppage  at  e  of  induction  shocks  ; 
«,  /,  gradual  relaxation  of  muscle. 

birds  are  not  tetanized  by  even  70  per  second.  If  shocks  are  sent  to  a 
muscle  at  the  rate  of  from  220  to  360  per  second,  instead  of  tetanus, 
there  may  be  only  a  momentary  contraction.  This  result  was  obtained 
by  Bernstein,  but  Kronecker  and  Stirling,  by  using  an  ingenious 
instrument  invented  by  them,  termed  a  tone-indudorium,'^  produced 
tetanus  by  shocks  so  rapid  as  24,000  per  second. 

The  study  of  tetanus  becomes  of  great  interest  when  we  remember 
that  many,  if  not  most,  of  the  muscular  movements  occurring  in  the 
body  are  of  this  character.     A  simple   muscular  movement,  such  as 

^  See  Landois'  and  Stirling's  Physiology,  vol.  i.  p.  717. 
I.  2d 


418  THE  CONTRACTILE  TISSUES. 

flexing  the  arm,  throws  certain  muscles  into  a  condition  of  normal 
tetanus.  This  is  proved  hy  Kronecker's  experiment  of  placing  two 
needles,  one  in  a  human  muscle  and  the  other  in  its  tendon,  and  con- 
necting both  with  a  telephone.  If,  then,  the  muscle  be  tetanized  by 
induction  shocks  coming  at  the  rate  of  about  100  per  second,  a  sound 
will  be  heard.  The  sound  is  a  proof  of  vibrating  motion.  The  pheno- 
mena of  shivering  of  muscles  is  an  example  of  incomplete  tetanus. 


Chap.  IX.— MODES  OF  EXCITING  MUSCULAR  CONTRACTION. 

In  addition  to  the  normal  stimulus  transmitted  by  a  nerve,  muscular 
contraction  may  be  excited  by  electrical,  mechanical,  thermal,  and 
chemical  stimuli  or  excitants. 

1.  Electrical  Stinmli. — An  electrical  stimulus  acts  most  effectively  on 
muscle  when  the  current  passes  in  the  direction  of  its  filires.  We  have 
already  seen  that  a  single  inchidion  shock  of  sufficient  strength  will 
cause  a  single  contraction  or  twitch,  and  that  a  number  of  shocks,  com- 
ing at  short  intervals  in  succession,  will  cause  tetanus,  spasm,  or 
cramp.  As  already  explained,  p.  374,  the  opening  shock  produces  a 
more  powerful  eflPect  than  the  closing  shock,  but  the  two  may  be  made 
nearly  equal  by  the  use  of  Yon  Helmholtz's  arrangement.  "When 
a  current  from  a  battery  of  voltaic  elements  is  passed  through 
a  muscle,  no  effect  in  the  way  of  contraction  can  be  observed, 
except  at  the  moments  of  opening  and  of  closing  the  cvurent,  or 
Avhen  the  ciurent  is  very  suddenly  and  largely  increased  or  dimin- 
ished in  strength.  If  the  muscle  forms  part  of  an  electrical  circuit 
and  the  cturent  is  opened  and  closed,  the  resulting  contraction  shows  a 
muscle  curve  differing  from  that  produced  on  imtating  the  nerve,  by 
the  contracted  muscle  relaxing  slowly,  so  that  the  time  of  relaxation  is 
very  much  longer  than  the  time  of  contraction.  The  passage  of  the 
current,  however,  causes  electrolytic  changes,  and  no  doubt  there  Avill 
be  also  the  production  of  heat  owing  to  the  resistance  opposed  by  the 
muscle  as  a  conductor  to  the  passage  of  the  electrical  current. 

Siippose  a  muscle  to  be  traversed  by  a  voltaic  current,  it  is  stimu- 
lated only  near  the  negative  pole  when  the  circuit  is  closed,  and  near 
the  positive  pole  when  the  circuit  is  opened,  and  if  the  motor  end-plates 
have  been  paralyzed  by  curara,  a  wave  of  contraction  may  be  observed 
starting  from  the  negative  pole  on  closing,  while  it  starts  from  the 
positive  jjole  on  opening.     (Eutherford.) 

It  is  important  to  observ-e  that  a  muscle,  wdth  paralyzed  nerve- 
endings,  responds  much  more  readily  to  the  opening  and  closing  shocks 


MODES  OF  EXCITING  MUSCULAR  CONTRACTION.        419 

of  a  voltaic  current  than  to  the  shocks  of  induced  or  Faradic  currents. 
This  is  probably  owing  to  the  muscle-protoplasm  not  responding  to  the 
very  short  and  sudden  stimulations  of  induced  cuirents,  while,  on  the 
other  hand,  the  motor  end-plates  and  the  nerves  themselves  readily 
respond  to  sudden  shocks  of  this  character.  It  would  appear  that  all 
kinds  of  protoplasm,  except  that  of  nerve  and  nerve-endings,  are  more 
susceptible  to  the  more  sluggish  opening  and  closing  shocks  of  a  voltaic 
current. 

2.  Mechanical  Stimuli. — The  effect  produced  by  a  mechanical  stimulus 
depends  upon  the  intensity  of  the  stimulus  and  the  rapidity  with  which 
it  acts.  Pressure  upon  a  niuscle,  if  slowly  applied,  may  not  excite  a 
contraction,  but  if  the  pressure  be  made  suddenly,  contraction  may  be 
the  result.  When  a  muscle  is  stimulated  by  any  mechanical  excitant, 
the  result  is  not  only  a  contraction  passing  from  the  excited  point 
through  the  whole  of  the  muscle,  but  a  permanent  coriti"action  at  the 
point  touched.  This  contraction,  termed  by  Schiflf,  its  discoverer, 
idio-muscular  contraction,  may  be  observed  in  the  living  man  when  a  blow 
IS  struck  with  a  blunt  body  across  a  muscle,  and  perpendicularly  to  the 
direction  of  its  fibres.  This  produces  a  local  contraction  like  a  weal,  or 
^s  if  there  was  a  bit  of  whip  cord  beneath  the  skin.  There  is  then  a 
contraction  which  extends  the  whole  length  of  the  muscle,  and  when 
this  contraction  has  disappeared,  there  remains  at  the  point  of  excita- 
tion a  transverse  swelling,  which  lasts  for  a  certain  time.  A  muscle 
may  pass  into  a  state  of  tetanus,  if  the  nerve  supplying  it  is  irritated  by 
■successive  mechanical  shocks. 

3.  Thermal  Stimuli. — The  sudden  passage  of  a  muscle  from  one  tem- 
perature to  another  considerably  higher  or  lower  than  the  first  may 
■excite  muscular  contractions,  and  as  the  temperature  is  raised  from 
28°  C.  to  45°  C,  the  individual  contractions  become  stronger.  About 
"60°  C,  tetanus  may  be  produced.  Above  this  limit,  the  myosin  or  other 
albuminous  constituent  of  the  muscle  coagulates,  and  the  muscle 
becomes  stiflT.  The  effect  of  heat  on  a  muscular  structure  is  strikingly 
illustrated  by  the  action  of  heat  on  the  heart  of  a  frog,  an  experiment 
which  may  be  readily  performed  by  means  of  the  arrangement  shown  in 
Fig.  279.  In  this  case,  however,  the  heat  acts  not  merely  on  the 
muscular  fibre,  but  also  on  the  intrinsic  nervous  mechanism  or  ganglia 
of  the  organ.     (See  Heart.) 

4.  Chemical  Stimuli. — A  great  many  chemical  agents  cause 
■contractions  by  their  influence  on  the  chemical  composition  of  the 
imiscle  or  of  the  nerve  supplying  it.  Amongst  the  agents  which 
•excite  contraction  are  the  fixed  alkalies,  the  mineral  acids,  acetic, 
oxalic,  tartaric,  and  lactic  acids,  alcohol,  ether,  creosote;  the  neutra,! 


420 


THE  CONTRACTILE  TISSUES. 


alkaline  salts,  such  as  chloride  of  sodium,  and  sulphates  and  carbonates^ 
of  the  alkalies ;  metallic  salts,  such  as  those  of  iron,  zinc,  copper,  silver, 
and  lead,  and  concentrated  solutions  of  urea,  sugar,  and  glycerine. 
These  excite  contraction  when  used  as  weak  solutions,  and  \\\  the  case- 
of  several,  the  solution  must  be  considerably  stronger  before  it  has  any 
effect  on  the  nerve  of  the  muscle.  A  Aveak  solution  of  bile  also  stimu- 
lates muscular  fibre.  Neutral  alkaline  salts  act  to  the  same  extent  on 
muscle  and  nerve.     The  vapour  of  hydrochloric  acid  causes  single  con- 


FiG.  279. — Arrangement  for  studying  the  action  of  heat  on  a  frog's 
heart.  A  copper  plate,  carrying  at  one  end  two  delicate  levers, 
6,  moving  on  a  joint  at  d ;  the  heart  is  placed  underneath  the 
levers  near  d,  one  on  the  auricular  and  the  other  on  the  ventricu- 
lar portion,  and  the  movements  of  the  levers  are  recorded  on  the 
cylinder  e.  When  heat  is  applied  by  the  spirit  lamp,  /,  to  the 
end  of  the  copper  plate,  the  heart  beats  faster  and  faster  until  it 
passes  into  a  state  of  tetanus,  from  which  it  may  recover  if  the 
copper  plate  is  cooled  with  a  piece  of  ice. 

tractions,  while  chlorine  gas  produces  tetanus.  It  is  said  that  the 
vapour  of  bisulphide  of  carbon  stimulates  the  nerves  and  not  the  mus- 
cular fibres.  Very  dilute  solutions  of  caustic  soda  or  caustic  potash 
first  stimulate  and  then  kill  both  nerve  and  muscle. 

Certain  solutions  cause  rhythmic  movements  in  muscle.  The  most 
efficient  fluid  for  this  purpose  is  called  Biedermann' s  fluid,  prepared  by 
dissolving  5  grammes  of  chloride  of  sodium,  2  grammes  of  alkaline 
phosphate  of  soda  and  "5  gramme  of  carbonate  of  soda  in  1  litre  of 
water      If  the  sartorius  muscle  of  a  froa;,  to  which  curare  has  been 


MODES  OF  EXCITING  MUSCULAR  CONTRACTION.        421 

given  so  as  to  paralyze  the  motor  end-plates,  is  immersed  in  this  solu- 
tion so  that  about  one  half  of  the  long  thin  muscle  dips  into  it,  the  muscle 
Tjegins  to  contract  rhythmically  in  a  manner  analogous  to  the  pulsations 
of  the  frog's  heart.  This  is  an  interesting  experiment,  as  suggesting 
that  rhythm  may,  to  some  extent  at  least,  depend  on  the  chemical 
composition  of  the  fluids  circulating  through  the  rhythmic  organ.  All 
of  these  substances  possibly  excite  either  the  nerve  or  the  muscle  by 
absorbing  water  from  them,  as  the  contractions  resemble  those  follo"vving 
rapid  drying  of  a  muscle  or  nerve  by  exposure  to  the  air.  Distilled 
water  injected  into  the  blood-vessels  of  a  muscle  excites  the  contraction 
■of  individual  fibrillae,  producing  the  local  quiverings  called  fibrillar  con- 
tractions ;  but  it  rarely  excites  contraction  when  applied  directly  to  the 
nerve  or  muscle. 


Chap.  X.— THE  PRODUCTION  OF  HEAT  BY  MUSCLE. 

The  apparatus  required  in  investigating  the  thermal  phenomena  of 
muscle  consists  of  a  galvanometer  of  small  resistance,  and  a  thermo- 
-electric  pile,  or  thermo-electric  needles.  A  thermo-electric  needle  is  com- 
posed of  an  iron  wire,  to  each  end  of  which  is  soldered  a  copper  or 
•German  silver  wire.  Several  such  needles  are  passed  through  the 
anuscle  so  that  one  set  of  junctions  of  iron  -with  copper,  or  iron  with 
German  silver,  is  embedded  in  the  muscle,  and  the  other  set  is  exposed 
to  the  air.  The  adjacent  ends  of  the  needles,  composed  of  copper  or 
silver,  are  in  connection  with  two  wires  which  go  to  the  galvanometer. 
This  arrangement  is  not  very  delicate,  and  for  more  refined  investiga- 
tions a  thermo-electric  pile  is  necessary.  A  pile  consists  of  short  bars  of 
bismuth  and  antimony,  having  each  end  of  a  bar  of  bismuth  soldered  to 
the  end  of  a  bar  of  antimony,  the  bars  lying  parallel.  Thus  there  are 
two  sets  of  alternate  junctions,  one  of  which  may  be  applied  to  the 
body  giving  off  heat,  while  the  other  is  kept  at  as  near  a  uniform  tem- 
perature as  possible.  In  these  circumstances,  if  the  one  set  of  junctions 
becomes  hotter  than  the  other,  a  current  of  electricity  is  generated 
which  deflects  the  needle  of  the  galvanometer.  By  such  arrange- 
ments, it  will  be  found  that  there  is  a  deviation  of  the  galvano- 
meter needle  when  the  muscle  contracts,  owing  to  the  development 
of  a  thermo-electric  current,  from  the  metallic  junction  in,  or  applied 
to,  the  muscle  being  raised  to  a  higher  temperature  than  the  other 
junction  kept  at  a  constant  temperature  in  a  vessel  of  boiling  water  or 
in  melting  ice.  Heidenhain  has  shown,  by  the  use  of  extremely  delicate 
arrangements  of  this  nature  (Fig.  280),  that  the  instantaneous  excitation 


422 


THE  CONTRACTILE  TISSUES. 


of  the  nerve  supplying  a  muscle  is  attended  by  a  rise  of  teniperatnrc  iir 
the  muscle. 

The  development  of  heat  in  a  muscle  depends — (1)  ;ipon  its  tension  ; 
(2)  on  the  work  done ;  and  (3)  on  the  state  of  fatigue  of  the  muscle. 

1.  Tenmiu  unci  Heat. — The  more  a  muscle  is  stretched,  the  greater  will' 
1)0  the  amount  of  heat  developed  when  it  contracts.  According  to- 
Beclard  and  Heidenhain,  a  muscle  develoj)s  its  maximum  amount  of 
heat,  supposing  the  intensity  of  the  stimulus  to  remain  the  same,  when 
it  is  so  stretched  as  to  be   unable   to   contract   at   all.     This   occurs- 


Fio.  280. — Heidenhain's  arrangement  for  studying  the 
heat-phenomena  of  muscle,  a,  gastrocnemius  muscle  of 
a  frog  having  a  small  thermo-electric  pile,  6,  in  contact 
with  it.  The  fifrure  f>  in  the  upper  left-hand  comer  shows 
the  surface  of  the  thenno-electric  pile,  consisting  of  \T< 
junctions,  c,  Is  a  frame  bearing  the  pile  ;  d,  support  of 
the  frame  c,  with  a  counterpoise  e  attached  to  it ;  /,  j\ 
two  glasses  containing  melting  ice  to  give  a  uniform  tem- 
perature to  the  other  thermal  junctions,  {/,  h. 

in  tetanus  of  a  limb  when  the  antagonistic  muscles  oppose  each  other, 
a  fact  which  accounts  for  the  high  temperature  observed  in  cases  of 
tetanus. 

2.  Work  Done  and  Heat. — As  to  the  relation  between  the  heat  produced 
in,  and  the  work  done  by,  a  muscle,  when  the  muscle  remains  con- 
tracted supporting  a  weight  sufficient  again  to  stretch  it,  no  effective 
work  is  done,  and  energy  appears  only  as  heat.  Energy  appeared  as-' 
motion  during  the  contraction,  Ijut  this  portion  disappeared  when  the 


THE  PRODUCTION  OF  HEAT  BY  MUSCLE.  423 

weight  restored  the  muscle  to  its  original  length.  Again,  the  energy  of  a 
contracted  muscle  appears  as  heat,  and  that  of  a  contracting  muscle  either 
as  heat  or  mechanical  work,  or  both.  If  we  add  the  energy  appearing 
in  the  form  of  heat  in  a  contracting  muscle  to  the  energy  liberated  as 
mechanical  work,  the  sum  is  the  total  amount  of  energy  expended  during 
the  contraction.  When  a  muscle  lifts  a  series  of  gradually  increasing 
weights  up  to  a  given  height,  the  amount  of  heat  increases  with  the  work 
done  up  to  a  maximum  point  peculiar  to  the  condition  of  the  muscle  at 
the  time.  If  the  weight  be  still  increased,  it  will  not  be  lifted  so  high, 
but  the  work  done  will  be  greater  and  the  amount  of  heat  generated  in 
these  circumstances  will  be  less.  It  follows  that  the  maximum  pro- 
duction of  heat  by  a  given  muscle  is  reached  sooner  than  its  maximvim 
amount  of  work.  The  greater  the  heat,  the  smaller  will  be  the  mechani- 
cal work,  and  vice  versa.  The  heat,  therefore,  produced  during  work 
is,  in  the  same  time,  inversely  proportional  to  the  amount  of  work. 
Several  large  contractions  liberate  more  heat  than  a  greater  num- 
ber of  small  contractions,  even  although  the  amount  of  work  done" 
be  the  same  in  both  cases,  or  in  other  Avords,  large  contractions  cause 
greater  changes  in  the  muscle  substance  than  a  greater  number  of  small 
contractions.  Lastly,  suppose  a  muscle  does  work  by  a  number  of  small 
contractions  in  a  given  time,  in  each  case  lifting  a  weight,  more  heat  will 
be  produced  than  if  the  muscle  kept  up  the  same  Aveight  for  the  same 
time  by  being  in  a  state  of  tetanus. 

3.  Fatigue  and  Heat. — With  regard  to  fatigue,  it  may  be  stated  that  as 
a  muscle  becomes  exhausted  by  successive  excitations,  or  by  the  approach 
of  death,  both  the  amount  of  work  done  and  the  production  of  heat 
simultaneously  diminish.  The  two  quantities,  however,  do  not  diminish 
equally  :  heat  diminishes  more  rapidly  than  work,  so  that  it  is  possible 
to  have  a  muscle  capable  of  performing  a  small  quantity  of  mechanical 
work,  but  at  the  same  time  producing  no  appreciable  amount  of  heat. 

Heat  to  a  small  amount  is  also  produced  by  the  relaxation  of  a  muscle, 
indicating  that  this  is  not  merely  a  passive  process,  but  that  it  also  in- 
volves a  small  amount  of  metabolism. 

The  venous  blood,  coming  from  a  muscle  in  a  state  of  activity, 
is  cceteris  paribus  warmer  by  '6"  C.  than  that  flowing  from  a  muscle 
at  rest ;  and  it  has  been  ascertained  that  the  gastrocnemius  of  a  frog, 
deprived  of  blood,  will  show  an  increase  of  about  "001°  to  •005°  C. 
for  each  contraction,  until  it  becomes  much  fatigued.  Tetanus  of  the 
same  muscle  for  two  or  three  minutes  will  produce  a  rise  of  temperature 
of  -014°  to  -018°  C.  Billroth  and  Fick  determined  the  heat  produced  by 
tetanus  of  the  muscles  of  mammalia  whilst  the  blood  was  circulating  as 
equal  to  a  rise  of  5°  C.    Leyden  also  foimd  a  rise  of  temperature  during 


424  THE  CONTUACriLE  TISSUES. 

tetanus  in  animals,  and  Wiindcrlich  obsei'ved  the  same  phenomena  in 
I)atients  suffering  from  tetanus ;  and,  further,  that  the  maximum 
temperature  was  not  attained,  in  these  cases,  until  after  death. 

The  heat  produced  by  a  contracting  muscle  is  a  physical  expression  of 
the  metabolic  changes  occurring  in  it.  The  chemical  energy  set  free  by 
these  metabolic  processes  appears  as  heat  and  mechanical  work,  and  the 
general  law  regulating  the  relation  of  these  is  that,  within  certain 
limits,  the  greater  the  resistance  off'ered  to  the  contraction  the  greater 
will  be  the  Avork  done.  In  these  circumstances,  as  much  as  one  fourth 
of  the  total  energy  may  appear  as  Avork,  the  remaining  three  fourths 
appearing  as  heat — a  remarkable  result  when  compared  Avith  that  of 
the  best  constructed  engines,  AA'hich  yield  as  AA^ork  only  one  ninth  part 
of  the  total  energy  supplied  to  them  by  the  oxidation  of  the  fuel,  while 
the  remaining  eight  ninths  are  manifested  as  heat. 

Chap.  XI.— THE  WORK  DONE  BY  MUSCLE. 

The  amount  of  Avork,  W,  done  by  a  muscle  Avhen  it  contracts  is 
measured  by  the  product  of  the  load,  I,  and  the  height,  h,  through 
Avhich  it  is  lifted.  Thus,  W  =  Z  x  h.  Hence  if  /  =  o,  that  is  if  the  muscle 
has  lifted  no  weight,  no  Avork  has  been  done ;  and  again  if  the  muscle  be 
so  over  loaded  that  /i  =  o,  there  Avill  be  no  Avork,  as  the  muscle  has  not 
contracted.  The  Avork  done  by  a  healthy  muscle  in  lifting  a  Aveight  will 
vary  according  to  the  strength  of  the  stimulus  and  the  Aveight  to  be 
lifted.  A  feAv  experiments  made  Avith  Von  Helmholtz's  myograph 
(Fig.  15,  p.  28)  in  Avhich  the  muscle  is  stimulated  by  single  induction 
shocks  of  equal  intensity,  will  show  this  clearly. 

a.  The  Contraction  as  a  Function  of  the  Stimulus. — Suppose  the  gastroc- 
nemius muscle  of  a  frog  is  loaded  AAdth  say  a  weight  of  10  grammes,  and 
the  apparatus  is  arranged  for  a  single  induction  shock.  Removing  the 
secondary  coil  of  the  induction  machine  to  a  considerable  distance  from 
the  primary,  let  a  single  shock  be  sent  to  the  muscle.  If  no  contraction 
folloAvs,  let  the  secondary  coil  be  moved  nearer  the  primary  until  the 
first  visible  contraction  is  obtained  and  recorded.  This  point  has  been 
termed  the  point  of  liminal  intensity  of  the  stimulus.  Then  advancing 
the  secondary  coil  ouAvards  definite  distances  nearer  the  primary, 
let  each  contraction  be  recorded  as  an  ordinate  on  the  abscissa  line 
at  distances  proportional  to  the  distances  the  secondary  coil  has 
been  moved. 

Such  a  method  shoAvs  that  the  amount  of  contraction  increases  Avdth 
the  increase  of  stimulus,  at  first  rapidly,  then  more  sloAvly,  until  a  maxi- 
mum is  reached ;  the  maximum  remains  for  some  time,  and  afterwards 


TEE  WORK  DONE  BY  MUSCLE.  425 

the  amount  of  contraction  may  become  less  owing  to  the  fatigue  of  the 
muscle  from  repeated  stimulations.  As  will  be  seen  in  the  course  of  this 
■discussion,  the  amount  of  contraction  alone  is  no  measure  of  the  amount  of 
muscle  work.  This  depends,  as  already  pointed  out,  on  the  product 
of  the  amount  of  the  contraction  and  the  load  lifted. 

/?.  The  Contraction  as  a  Function  of  the  Resistance. — Suppose  in  this 
experiment  the  strength  of  the  stimulus  is  the  same,  while  the  load 
which  the  muscle  has  to  lift  is  gradually  increased.  Let  a  contraction 
be  recorded  when  there  is  no  load  to  the  muscle  at  all.  Then  load 
successively  with  10,  20,  30,  etc.  grammes,  and  record  the  several  con- 
tractions at  proportionate  distances  along  the  abscissa  line.  It  can  thus 
be  shown  that  as  the  weight  is  increased  from  zero  upwards,  the  con- 
traction increases ;  as  the  weight  continues  to  be  increased,  contraction 
.also  increases,  but  more  slowly,  and  beyond  a  certain  point  increase  in 
the  weight  is  followed  by  a  diminution  in  the  amount  of  contraction. 

y.  The  Contraction  as  a  Function  of  the  Time  between  Successive  Stimulations. 
— In  a  third  experiment,  it  is  interesting  to  observe  the  effect  of  varying 
the  time  between  successive  stimulations,  keeping  the  load  or  resistance 
and  also  the  strength  of  the  stimulus  the  same.  This  may  be  done  by 
sending  shocks  to  the  muscle  at  intervals  of  a  second,  half  a  second, 
a  third  of  a  second,  and  so  on.  The  result  shows  that  if  a  certain 
amount  of  time  is  allowed  to  elapse  between  successive  shocks,  the 
same  amount  of  work  may  be  over  and  over  again  repeated,  but  when 
the  shocks  come  too  quickly,  the  work  quickly  diminishes,  or,  in  other 
words,  the  muscle  becomes  fatigued. 

8.  Measurement  of  the  Work  Done. — The  amount  of  work  done  by  a 
muscle  at  a  given  time  will  depend  on  the  strength  of  the  stimulus,  the 
amount  of  the  resistance  to  be  overcome,  and  the  condition  of  the  muscle 
as  regards  fatigue,  and  no  doubt  there  will  be  for  a  given  muscle,  after  a 
period  of  rest,  a  maximum  amount  of  possible  work  corresponding  to  a 
•certain  strength  of  stimulus  and  a  certain  load  to  be  lifted,  or  resistance 
to  be  overcome.  As  already  pointed  out,  the  work  done  is  ascertained 
by  multiplying  the  actual  amount  of  shortening  of  the  muscle  by  the 
weight  lifted.  Suppose,  for  example,  a  muscle  lifts  10  grammes 
20  millimetres  in  height,  the  work  done  is  200  gramme-millimetres. 
This  may  also  be  shown  diagrammatically  by  drawing  an  abscissa  line, 
marking  off  upon  it  the  distances  proportionate  to  different  weights,  and 
drawing  as  ordinates  the  actual  work  done  in  the  case  of  each  weight. 
A  line  drawn  through  the  summits  of  the  ordinates  will  give  the  curve 
of  the  work  done  with  the  same  stimulus  and  increasing  loads.  Such  a 
line  would  of  course  slope  upwards.  The  heights,  however,  of  the 
marks  made  on  the  smoked  glass-plate  of  the  myograph  would  diminish 


42G 


THE  CONTRACTILE  TISSUEiS. 


as  the  amount  of  work  increased.  Thns,  supp.ose  the  diagram  in  Fig.  281 
represents  the  result  of  an  experiment  of  a  muscle  lifting  gradually 
increasing  Aveights,  The  figures  at  the  side  indicate  millimetres,  and 
the  figures  along  the  liase  line  indicate  grammes.     It  is  clear  that  the 


Fig.  281.— Diagram  to  show  the  mode  of  measuring  muscle  work. 

Avork  done  as  indicated  by  the  first  line  on  the  left  is  10  x  5  =  50  gramme- 
millimetres  ;  the  next,  20  x  5  =  100  gramme-millimetres,  etc.  ;  Avhile  the 
last  on  the  right,  100  x  3  -=  300  gramme-millimetres. 

Weber  has  given  the  foUoAving  figures  with  reference  to  the  work  done  by  the 
gastrocnemius  muscle  of  a  frog  :  — 


Weisrht  Lifted  in 
Grammes. 

• 

Height  in 
Millimetres. 

Work  done  in 

Gramme- 
Millinietres. 

5 
15 

25 
30 

27-6 

251 

1 1  -45 

7-3 

138 
376 

286 
219 

This  table  shows  that  the  work  increases  with  the  weight  up  to  a  certain 
maximum,  after  which  a  diminution  occurs,  more  or  less  rapidly  according  as  the 
muscle  is  fatigued. 

To  maintain  a  muscle  in  a  tetanic  state,  successive  stimuli  are  required. 
The  first  few  stimuli  cause  the  muscle  to  contract,  and  then  work  is 
done,  but  no  work  is  done  during  the  tetanic  state.  The  chemical 
changes  set  up  by  the  successive  stimulations  required  to  keep  u]> 
tetanus  find  expression  as  heat  and  as  continued  contraction.  A 
tetanic  contraction  will  do  more  work  than  will  be  done  by  a  single 
contraction  caused  by  a  stimulus  of  the  same  strength  as  the  individual 
stimuli  producing  the  tetanus,  but  the  tetanus  will  of  course  quickly 
produce  fatigue  in  consequence  of  the  rapid  metabolism  taking  place 
in  the  muscle. 

Static  Fwce  of  a  Muscle. — In  charging  a  contracting  muscle  Avith 
gradually  increasing  Aveights,  there  arrives  a  time  Avhen  the  elongation 
due  to  tension  of  the  muscle  exactly  compensates  the  contraction  of  the 
muscle.  When  this  is  so,  the  muscle  is  in  a  state  of  equilibrium,  and 
the  Aveight  expresses  what  Weber  termed  its  static  force,  or  absolute  farce. 
The  force  is  stated  usually  as  the  number  of  grammes  per  square  centi- 


THE  WORK  DONE  BY  MUSCLE. 


427 


metre.-^  This  force  for  frog's  muscle  has  been  found  to  be  2,800  to 
3,000  grammes,  and  for  human  muscle,  to  be  from  7,000  to  lOjOOO" 
grammes,  that  is  to  say,  a  strip  of  frog's  muscle  having  a  transverse 
section  of  a  square  centimetre  would,  when  stimulated,  itndergo  no  change 
in  length  with  a  weight  of  say  3,000  grammes  attached  to  one  end. 

The  force  of  individual 
muscles  in  the  human  body 
may  be  measured  by  means 
of  instruments,  termed  di/n- 
amometers,  one  of  Avhich,  ad- 
apted for  testing  the  muscles 
of  the  arms  and  hands,  is 
seen  in  Fig.  282.  On  com- 
pressing this  instrimient  with 
both  hands,  a  strong  man  may 

force  round  the  index  to  70,  representing  kilogrammes  of  pressure. 
The  muscles  of  women  are  feebler  than  those  of  men.  With  another 
kind  of  dynamometer,  a  man,  by  pulling,  may  move  the  index  to  150 
kilogrammes. 


Fig.  2S2. — Dynamometer,     a,  b,  strong  steel 
spring  ;  c,  scale. 


Chap.  XII.— THE  MUSCLE  SOUND. 

When  a  stethoscope  is  firmly  applied  over  a  powerfully  contracting 
muscle,  such  as  the  biceps  in  a  muscular  man,  a  deep  tone  is  heard, 
which  is  produced  by  about  twenty  (19-5  ?)  vibrations  per  second. 
This  sound  was  first  detected  by  AVollaston.  It  may  also  be  heard 
during  profound  stillness,  as  in  the  middle  of  the  night,  if  we  stop 
the  ears  and  powerfully  contract  the  muscles  of  mastication.  This- 
tone  is  the  same  in  pitch  as  the  resonance  tone  in  the  ear.  The 
muscular  sound,  according  to  Von  Helmholtz,  is  produced  by  the  varia- 
tions of  tension  which  occur  during  the  fonuation  of  a  continuous- 
muscular  contraction.  It  is  probable  that  the  sound  heard  is  not  that 
due  to  twenty  vibrations  per  second,  which  number  of  impulses  on  the 
ear  would  not  produce  the  sensation  of  a  tone,  but  to  forty  vibrations 
per  second,  or  the  first  overtone  or  harmonic  of  the  fundamental  tone. 

The  existence  of  the  muscular  tone  renders  it  probable  that,  to  secure 
the  contraction  of  a  voluntary  muscle  in  man  during  life,  about  twenty 
impulses   per   second   are  transmitted  from  the  nerve-centres  to  the 

^  To  find  the  mean  transverse  section  of  a  muscle— (1)  Ascertain  tlie  volume  by 
dividing  the  absolute  weight  of  the  muscle  by  its  specific  gravity,  1'058  (C.G.S.), 
and  then  (2)  divide  the  volume  by  its  length.  This  gives  the  mean  transverse 
section.     (Landois.) 


428  THE  CONTRACTILE  TISSUES. 

muscle  along  the  motor  nerves.  Of  course  it  is  understood  that  the 
contraction  is  not  merely  a  twitch,  as  Avhen  one  quickly  flexes  and 
extends  the  arm,  but  such  a  contraction  of  the  muscle  as  is  necessary  to 
support  a  weight  for  a  short  time.  This  condition  of  contraction  may 
be  regarded  as  a  kind  of  normal  tetanus,  and  no  doubt  the  great  majority 
of  voluntary  contractions  are  of  this  nature.  Irritation  of  a  motor 
nerve  or  of  the  spinal  cord  produces  a  muscular  sound  of  the  pitch  above 
mentioned,  but  it  is  remarkable  that  if  tetanus  is  produced  in  a  muscle 
by  rapid  interruptions  of  the  j^rimary  circuit  produced  by  a  vibrating 
spring,  the  pitch  of  the  muscular  sound  so  produced  is  exactly  that 
produced  by  the  number  of  vibrations  of  the  spring,  and  by  increasing 
or  diminishing  the  number  of  vibrations  of  the  spring,  the  pitch  of  the 
resulting  muscular  sound  can  be  raised  or  lowered  in  the  scale.  Thus, 
a  tone  may  be  heard  corresponding  to  a  pitch  of  from  700  to  1000 
vibrations  per  second,  when  the  number  of  vibrations  of  the  interrupting 
spring  reaches  those  amounts.  If  the  nerve  is  irritated,  the  sound  is  not 
so  loud. 


Chap.  XIII. —THE  PHENOMENA  OF  MUSCULAR  FATIGUE. 

A  muscle  becomes  fatigued  after  continuous  work.  Fatigue  means  a 
diminished  power  of  work.  Up  to  a  certain  point,  the  substances  pro- 
duced in  a  contracting  muscle  are  eliminated  as  quickly  as  they  are 
formed,  and  at  the  same  time  new  materials  necessary  for  the  repair  of 
the  muscle  are  supplied.  There  is  thus,  as  it  were,  a  balance  between 
the  two  processes.  When,  however,  the  muscle  is  excited  to  very 
fre<iuent  contraction,  the  products  of  waste  accumulate  in  the  muscle, 
and  probably  also  sufficient  time  is  not  allowed  for  the  supply  of 
reparative  material.  The  waste  products  are  chiefly  acid  phosphate  of 
potash,  and  carbonic  acid,  possibly  small  amounts  of  free  phosphoric 
acid,  and  such  nitrogenous  matters  as  are  found  in  extract  of  meat, 
creatin,  creatinin,  etc.,  p.  361.  The  injection  through  the  vessels  of  a 
muscle  of  a  -6  per  cent,  solution  of  common  salt,  a  weak  solution  of 
sodium  carbonate, '  or  a  weak  solution  of  permanganate  of  potash, 
removes  these  substances,  and  the  muscle  may  again  become  fit  to  do 
work.  As  oxygen  is  necessary  for  the  metabolic  processes  occurring 
in  a  muscle,  it  is  evident  that  if  the  supply  of  this  gas  be  much 
diminished,  the  muscle  will  rapidly  become  fatigued.  Further,  as  the 
muscle  becomes  fatigued,  it  consumes  less  oxygen  and  produces  a 
smaller  quantity  of  waste  products. 

Fatigue  diminishes  the  cohesion  of  muscle,  and  makes  the  muscle 
more  easily  stretched  by  weight ;  it  has  apparently  little  or  no  effect 


THE  PHENOMENA  OF  MUSCULAR  FATIGUE. 


42^ 


upon  its  elasticity,  it  lowers  irritability,  and  it  lengthens  the  period  of 
latent  stimulation.  If  a  muscle  is  stimulated  by  shocks  sent  to  it  at 
equal  intervals  of  time,  it  will  contract  with  each  shock,  and,  for  a 
short  time,  the  amount  of  each  contraction  may  slightly  increase.  The 
duration  of  each  contraction  steadily  increases.  By-and-bye,  however, 
as  the  muscle  becomes  fatigued,  the  amount  of  contraction  diminishes- 
until  the  muscle  does  not  contract  at  all,  but  the  duration  increases' 
throughout  the  whole  experiment.  The  phenomena  in  the  first  part  of 
the  experiment  are  illustrated  by  the  tracing  in  Fig.  283.     This  tracing 


Diapason-.  100.  V.D 


Fio.  283. — Consecutive  tracings  of  the  contractions  of  the  gastrocnemius 
muscle  of  a  frog,  showing  the  effects  of  fatigue.  The  beginning  of  the 
contraction  is  the  commencement  of  the  curve  on  the  left.  The  first 
contraction  produced  the  lowermost  curve,  and  the  uppermost  curve  was 
the  last  made  in  the  experiment.  Chronograph,  100  vibrations  per 
second. 

was  taken  by  means  of  the  arrangements  described  on  p.  410,  with  the 
aid  of  the  apparatus  shown  in  Figs.  267  and  268.  It  shows  (1)  the 
gradual  lengthening  of  the  period  of  latent  stimulation,  as  indicated  by 
each  contraction  beginning  a  little  later  than  the  one  before  it ;  (2)  the 
gradual  increase  in  the  amount  of  contraction,  as  the  curves  at  the  top 
of  the  diagram  are  higher  than  those  at  the  foot ;  and  (3)  the  gradual 
lengthening  of  the  contraction,  by  the  muscle  losing  time  during  relaxa- 
tion.    The  experiment  was  not  carried  far  enough  to  show  the  diminution 


430  THE  CONTRACTILE  TISSUES. 

m  the  amplitude  of  the  contraction  caused  by  fatig\ie.  During  fatigue,  a 
muscle  returns  to  its  original  length  more  slowly  after  a  contraction. 
As  has  been  already  stated,  the  work  done  diminishes  rapidly  during 
fatigue.     The  absolute  muscular  force  is  diminished  by  fatigue. 

According  to  Kronecker,  a  muscle  is  fatigued  more  quickly  when  it 
<loes  work  than  when  it  contracts  Avithout  accom})lishing  work,  or  when 
it  is  merely  tetanized.  The  fatigue  which  follows  Avork  depends  upon 
the  amount  of  the  resistance  to  be  overcome  by  the  Avork,  and  the  time 
■during  Avhich  the  resistance  acts  against  the  muscle.  Loading  a  muscle 
oidy  during  its  contraction  Avill  not  fatigue  it  so  soon  as  if  it  is  loaded 
both  during  its  contraction  and  relaxation,  indicating  that  metabolic 
changes  occur  to  some  extent  during  relaxation  as  Avell  as  during  con- 
traction. A  nniscle  becomes  most  rapidly  fatigued  Avhen  stimulated  to 
poAverful  contractions  AA^hich  are  not  able  hoAA-ever  to  OA^ercome  the 
resistance,  say  of  a  heavy  Aveight. 

Probably  the  end-plates  become  fatigued  first,  and  it  Avould  appear 
that  the  muscle  substance  becomes  sooner  fatigued  than  the  nerve. 
(Waller.)  The  circulation  of  various  substances  in  the  blood,  such  as 
-Strychnin,  veratrin,  ptomains,  also  affects  the  metabolism  of  muscle, 
iis  shoAvn  by  changes  in  the  behaviour  of  the  muscle  during  fatigue. 
The  capacity  for  work  diminishes  Avith  elcA^ation  of  temperature,  and  if 
the  temperature  does  not  pass  a  certain  limit,  about  40°  C.  for  the  muscle 
■of  a  frog,  the  muscle  may  recoA^er  its  original  poAver  on  cooling. 

«C"HAP.  XIV.— THE  NUTRITIVE  CHANGES  OR  METABOLISM  IN  MUSCLE. 

The  metabolic  changes  occurring  in  muscular  tissue  are  very  active 
iind  very  complicated.  A  muscle  in  a  state  of  rest,  and  supplied  with 
blood,  absorbs  oxygen  and  eliminates  carbonic  acid,  and  the  amount  of 
•carbonic  acid  produced  is  less  than  can  be  accounted  for  by  the  amount 
•of  oxygen  used.  A  resting  muscle,  e\'en  AAathout  the  blood  circulating- 
through  it,  shoAvs  similar  gaseous  exchanges,  as  it  retains  its  irritability 
longer  in  air,  or  in  oxygen,  than  in  an  atmosphere  containing  no  oxygen. 
It  is  clear,  then,  that  even  during  rest  metabolism  takes  place  in  living- 
muscle  ;  in  other  Avords,  it  respires  like  a  liAang  being. 

During  contraction,  these  exchanges  are  much  increased,  and  the 
elimination  of  carbonic  acid  goes  on  more  rapidly  than  the  absorption 
of  oxygen.  A  muscle  actively  contracting  uses  four  or  five  times  as 
much  oxygen  as  it  uses  during  rest,  and  it  also  excretes  a  much 
larger  amount  of  carbonic  acid.  Thus,  in  the  body,  the  A^enous  blood 
floAvdng  from  an  active  muscle  is  richer  in  carbonic  acid  and  poorer  in 
oxygen  than  the  venous  blood  floAving  from  the  same  muscle  at  rest. 


NUTRITIVE  CHANGES,  OR  METABOLISM  IN  MUSCLE.    431 

Further,  a  tetanized  muscle  produces  more  carbonic  acid  than  can  be 
accounted  for  by  the  oxygen  supplied  to  it — that  is  to  say,  the  meta- 
bolic processes  tend  to  the  production  of  more  carbonic  acid.  While, 
therefore,  it  is  correct  to  say  that,  normally,  muscles  require  oxygen,  we 
must  not  assume  that  the  metabolism  occui-ring  in  active  muscles 
absolutely  requires  a  supply  of  oxygen  from  without,  at  all  events  for 
some  time,  as  it  is  well  known  that  muscles  removed  from  the  body 
may  continue  to  contract  in  an  atmosphere  containing  no  oxygen.  In 
these  circumstances,  the  protoplasm  of  the  muscle  must  receive  oxygen 
set  free  by  decomposition  of  the  tissue  itself.     (See  pages  182,  183.) 

About  '4  per  cent,  of  glycogen  has  been  found  in  the  muscles  of  the 
frog,  and  it  is  said  that  the  amount  is  diminished  in  muscles  that  have 
passed  through  a  period  of  active  contraction.  Muscles  may  show  con- 
tractile power  mthout  the  presence  of  this  substance.  Active  muscles 
also  contain  a  smaller  amount  of  creatin  and  creatinin  and  of  fatty  acids. 
The  amount  of  urea  is  not  increased.  The  amount  of  water  in  muscle 
is  increased  by  contraction.  It  has  also  been  ascertained  that  during 
contraction  the  substances  that  may  be  extracted  by  Avater  from  muscle 
are  diminished,  while  those  extracted  by  alcohol  are  increased.  At  the 
same  time,  the  muscle  becomes  acid  from  the  development  of  paralactic 
acid,  and  probably  of  free  phosphoric  acid,  and  the  amount  of  acid  formed 
increases  with  greater  muscular  activity.  The  circulation  of  the  blood 
is  more  active  in  a  contracting  muscle  than  in  one  at  rest. 

According  to  Bernard,  at  the  moment  of  contraction,  the  blood  is 
retained  in  the  capillaries,  and  does  not  enter  the  veins ;  it  passes  only 
into  the  veins  in  the  interval  of  muscular  contraction,  and  the  blood 
flowing  in  the  veins  from  a  contracting  muscle  is  dark  and  distinctly 
venous,  while,  if  the  muscle  is  in  a  state  of  repose,  it  is  more  red  and 
arterial.  As  shown  by  Gaskell,  the  small  blood-vessels  in  muscles 
are  dilated  during  contraction. 

The  exact  nature  of  the  chemical  processes  occiu-ring  in  muscle  is  not 
understood.  The  protoplasm  of  the  muscle  is  probably  built  up  by 
anabolic  processes  out  of  such  materials  as  proteids,  carbo-hydrates — as 
glycogen  or  sugar — and  fats,  saline  matters  and  water — and  then,  in  the 
presence  of  oxygen,  and  probably  associated  with  oxidations,  when  the 
muscle  contracts,  various  substances  are  formed  by  katabolic  pro- 
cesses, such  as  carbonic  acid,  water,  etc.  Immediately  after  a  contraction, 
the  substance  of  the  muscle  is  again  rapidly  built  up,  and  the  waste 
products  are  removed.  It  is  not  necessary  to  assume  that  in  these 
anabolic  and  katabolic  processes  the  whole  of  the  protoplasm  is  either  built 
up  anew  or  entirely  decomposed,  and  it  is  more  likely  that  a  substance 
exists  which  may  be  regarded  as  the  organic  (or  chemical  1)  basis  associated 


432  THE  CONTRACTILE  TISSUES. 

with  these  changes.  Suppose  we  call  this  substance  o:.,  the  substances 
above  enumerated  which  go  to  the  building  up  of  muscle  a;',  ;s",  a;"',  «''', 
etc.,  and  the  substances  formed  as  waste  products,  y,  y\  y",  y"\  ?/%  etc., 
then  the  anabolic  process  would  be  represented  by  x  +  a;'  +  o:"  +  x"'  +  a;'% 
etc.  -  muscle   protoplasm,    and  the  katabolic,    by  muscle   protoplasm 

Chap.  XV.— THE  PHENOMENA  OF  CADAVERIC  RIGIDITY. 

Soon  after  death,  muscles  become  firm,  thicker,  denser,  more  solid ; 
they  oppose  a  great  resistance  to  extension,  are  more  readily  torn,  and 
when  extended,  do  not  return  to  their  original  length.  This  state  is 
called  rigoi-  mortis,  or  cadaveric  rigidity.  Their  tonicity  has  disappeared, 
so  that  when  cut  across,  they  do  not  retract.  The  muscle  substance, 
Avhen  seen  in  thin  section,  has  lost  its  transparency.  In  this  condition, 
also,  muscular  irritability  is  lost,  but  within  a  certain  limit  of  time 
after  its  disappearance  it  may  return  on  the  injection  of  arterial  blood 
into  the  arteries.  The  muscle  is  strongly  acid,  a  reaction  due  to  the 
presence  of  lactic,  glycero-phosphoric  and  carbonic  acids,  and  acid 
phosphate  of  potash.  Cadaveric  rigidity  is  due  to  coagulation  of 
myosin  from  the  formation  of  the  acids.  The  change  comes  on  pro- 
gressively. At  first,  the  muscle  may  be  slightly  rigid,  but  still  irritable, 
but,  as  the  rigidity  increases,  the  irritability  diminishes,  until  a  stage 
is  reached  when  the  muscles  are  no  longer  irritable.  The  sudden 
stoppage  of  blood  flowing  to  a  muscle  at  first  increases  its  irritability; 
this  is  soon  diminished,  and  rigor  begins  to  appear.  If  the  circulation 
be  re-established  during  the  time  when  the  muscle  is  even  slightly 
irritable,  the  muscle  may  recover  and  the  irritability  entirely  return,  but 
Avhen  irritability  has  entirely  disappeared,  establishment  of  the  cir- 
culation cannot  restore  it.  Thus,  Brown-Sequard  removed  cadaveric 
rigidity  and  preserved  the  irritability  of  the  muscles  of  a  criminal  thirteen 
hours  after  execution,  and  two  hours  after  the  appearance  of  partial 
rigidity,  by  injecting  into  the  blood-vessels  warm  and  fresh  defibrinated 
human  blood  containing  oxygen.  In  this  case,  however,  the  muscles 
were  still  slightly  irritable  before  the  injection,  and  it  can  hardly  be  said 
that  irritability  was  restored  after  it  had  entirely  disappeared.  Eigidity 
may  commence  from  a  quarter  of  an  hour  to  twenty  hours  after  death. 
After  the  death  of  a  human  being,  rigor  usually  appears  in  the  following 
order — muscles  of  jaws,  muscles  of  trunk,  muscles  of  lower  limbs, 
muscles  of  upper  limbs.  As  it  supervenes,  the  body  becomes  gradually 
colder,  until  it  reaches  the  temperature  of  the  surrounding  atmosphere, 
and  at  the  same  time  irritability,  as  already  stated,  gradually  diminishes. 


THE  PHENOMENA  OF  CADAVERIC  RIGIDITY,  433 

Irritability  has  been  stated  by  Onimus  to  disappear  in  the  following 
order — left  ventricle,  stomach,  and  intestines,  in  55  minutes;  bladder 
and  right  ventricle,  in  60  minutes;  iris  in  105  minutes;  muscles  of 
face  and  tongue  in  180  minutes;  extensors  of  extremities,  about  one 
hour  before  flexors ;  and  in  muscles  of  trunk,  in  five  or  six  hours.  The 
complete  disappearance  of  irritability  coincides  with  the  complete 
establishment  of  cadaveric  rigidity.  This  lasts  for  a  period  of  from 
one  to  four  or  six  days,  and  then  it  begins  to  disappear,  slowly  vanish- 
ing from  the  muscles  in  the  order  in  which  it  supervened.  Then,  in 
turn,  cadaveric  rigidity  is  succeeded  by  putrefactive  changes.  As  to 
the  relation  of  these  phenomena  in  time,  the  general  rule  is  that  in 
cases  in  which  rigm'  mortis  supervenes  at  an  early  period  after  death 
(exhaustive  diseases,  in  animals  whose  muscles  have  been  exhausted  by 
the  prolonged  exertions  of  the  chase,  and  in  cases  of  death  by  tetanus, 
cholera,  strychnia,  or  lightning),  it  soon  disappears,  and  putrefaction 
comes  quickly,  whereas  in  cases  in  which  rigor  moiiis  is  late  in  appearing 
(as  in  the  sudden  death  by  accident  of  a  healthy  muscular  man)  it  lasts 
longer,  and  putrefactive  changes  come  on  late. 

Rigidity  of  muscle  may  also  be  caused  by  heat.  Thus,  at  a  temperature  of 
40°  C,  the  muscles  of  cold-blooded  auimals,  such  as  the  frog,  become  rigid,  while 
the  same  phenomenon  occurs  with  the  muscles  of  birds  at  53°  C,  and  of  mammals 
at  50°  C.  This  form  of  rigidity  is  not  the  same  as  that  of  rigor  mortis,  because  it 
is  no  doubt  due  to  the  coagulation  by  heat  of  other  proteids  than  myosin.  (See 
Chemistry  of  Muscle,  p.  360.)  A  miiscle  may  also  be  made  rigid  by  the  injection 
into  the  vessels  of  "1  to  "2  per  cent,  solutions  of  hydrochloric  or  lactic  acids,  and 
the  rigidity  may  be  removed  by  the  subsequent  injection  of  a  15  per  cent,  solution 
of  ammonium  chloride. 

A  muscle  may  be  frozen  so  as  to  be  solid  throughout,  and  yet  on  careful  thawing, 
it  may  still  be  found  to  be  slightly  irritable.  This  kind  of  rigidity  is  not,  there- 
fore, the  same  as  that  now  being  described.  Solutions  of  quinine,  digitalin, 
caffein,  veratrin,  hydrocyanic  acid,  ether,  chloroform,  oil  of  mustard,  fennel, 
aniseed,  when  given  internally,  favour  the  appearance  of  rigor,  and  the  same  is 
the  result  of  the  direct  contact  with  muscle  of  potassium  sulphocyanide,  ammonia, 
alcohol,  and  metallic  salts.     (Landois.) 


Chap.  XVI.— THE  GROWTH  AND  ATROPHY  OF  MUSCLE. 

The  embryonic  development  of  muscle  has  already  been  briefly 
alluded  to,  p.  312.  A  fibre  of  striated  muscle  is  developed  from  a 
single  cell,  which  increases  in  size  and  becomes  fusiform  in  shape.  The 
nucleus  repeatedly  divides,  and  the  surrounding  protoplasm  is  differen- 
tiated into  the  disc-like  arrangement  already  described.  In  the  muscles 
of  mammalia,  the  nuclei  leave  the  centre  and  pass  to  the  periphery  of 
I.  2  E 


434  THE  CONTRACTILE  TISSUES. 

the  fibre,  and  are  found  between  the  bundles  of  fibrils,  of  which  the 
fibre  is  now  composed.  The  sarcolemma  is  in  all  probability  the  mem- 
brane of  the  cell  from  which  the  fibre  was  formed,  but  some  have 
supposed  that  is  formed  by  special  cells,  Avhich  become  flattened  and 
blend  at  their  edges  to  form  a  membrane.  The  latter  view  is  probably 
erroneous.  A  fully  formed  muscle  consists  of  a  certain  number  of 
fibres.  It  is  a  familiar  observation  that  functional  activity,  in  a  normal 
condition,  Avill  cause  a  muscle  to  become  larger,  thicker,  and  stronger, 
and,  along  vnth.  these  changes,  there  is  an  increase  in  the  number  of 
fibres.  This  enlargement  is  due  both  to  the  development  of  new  fibres 
and  to  an  increased  thickening  of  older  ones,  by  interstitial  groArth. 
The  muscular  fibres  of  a  child  are  shorter  and  about  one  fifth  of  the 
breadth  of  those  of  an  adult.  Increased  and  regular  exercise  causes  an 
increased  growth  and  probably  also  a  development  of  new  fibres  from 
the  nuclei  under  the  sarcolemma.  Professor  Rutherford  points  out, 
however,  that  many  muscles,  such  as  those  of  the  muscles  of  respiration 
of  the  foetus,  grow  without  exercise,  in  consequence  of  the  "  germinal 
energy  of  the  tissue,"  influenced  probably  by  the  actiAaty  of  certain 
trophic  nerves.  A  mere  determination  of  nutritive  blood  to  a  muscle 
will  not  necessarily  cause  it  to  grow,  but  if,  along  with  this,  the  muscle 
is  caused  systematically  to  contract,  its  protoplasm  will  take  up  nutri- 
tive matter  to  an  increased  amount,  and  the  muscle  ■nail  increase  in  size 
and  strength,  until  it  reaches  a  limit  beyond  which  no  further  growth 
is  possible.  A  striking  example  of  the  growth  of  involuntary  muscular 
tissue  is  seen  in  the  development  of  the  muscular  wall  of  the  pregnant 
uterus.  During  gestation  this  organ  increases  from  about  1  ounce  to 
from  1|  to  3  pounds,  and  the  increase  is  largely  due  to  the  increase  in 
the  muscular  coat,  the  cells  of  which  become  enlarged  from  7  to  11 
times  their  length,  and  from  2  to  5  times  their  breadth  in  the  unim- 
pregnated  state.  Muscular  hypertrophy  is  also  seen  normally  in 
striated  muscle,  in  the  muscles  of  the  arm  of  a  labourer,  and  in  the 
limbs  of  gymnasts  and  dancers,  and  in  the  intermediate  variety  of 
muscle  in  hypertrophy  of  the  walls  of  the  left  ventricle  of  the  heart 
associated  ^Wth  contraction  of  the  orifice  of  the  aorta. 

The  opposite  condition  of  hypertrophy  is  atrophy,  as  seen  in  the 
wasted  muscles  of  a  paralytic.  The  muscles  become  thin,  soft,  and 
flabby,  and  when  examined  show  numerous  fatty  particles  in  the 
muscle  substance  (Fig.  170,  p.  312).  The  striation  also  becomes  less 
distinct.  The  small  fat  drops,  mostly  in  or  near  the  nuclei,  are  usually 
in  roAvs  parallel  to  the  longitudinal  striae  of  the  fibre.  The  small  drops 
may  by-and-bye  coalesce  to  form  larger  ones. 

If  muscle  be  divided  and  the  ends  be  brought  into  close  apposition. 


THE  GROWTH  Ai\D  A  TROPHY  OF  MUSCLE.  435 

they  may  be  joined  by  the  development  of  new  muscle  substance  arising 
from  proliferation  of  nuclei  and  the  formation  of  new  muscle  cells. 
•(Kraske.)  Various  pathologists  have  held  that  muscle  fibres  may  be 
regenerated  from  migrated  colourless  blood  corpuscles.  There  is  un- 
doubtedly a  physiological  regeneration  of  muscle  in  frogs  after  the 
■sleep  of  winter  and  probably  in  hypernating  animals.  A  wound  in 
muscle  may  therefore  not  be  healed  by  a  cicatrix  of  connective  tissue, 
if  the  margins  of  the  wound  are  closely  united,  but  if  the  wound  be  left 
partially  open,  the  cavity  will  be  filled  up  by  connective  tissue.^ 

Chap.  XVII. —THE  PROPERTIES  OF  NON-STRIATED  MUSCULAR 

FIBRE. 

AVhen  stimulated,  either  directly,  by  mechanical,  chemical,  or  ther- 
mal stimuli,  or  by  a  nervous  impulse,  involuntary  muscle  contracts. 
The  period  of  latent  stimulation  is  very  rnuch  longer  than  in  striated 
muscle,  and  the  contraction  takes  place  slowly,  and  lasts  for  a  length- 
ened period.     The  general  character  of  the  contraction  may  be  seen 


Fig.  284. — Tracing'  of  the  contraction  of  non-striated  muscular  fibre.  The 
upper  line  was  obtained  from  the  contracting  stomach,  and  the  lower 
from  the  contracting  bladder,  of  a  dog.  The  horizontal  mark  indicates 
the  moment  of  application  of  the  stimulus.  lu  this  tracing,  1  centimetre 
-  6  seconds. 

in  the  movements  of  the  intestine  of  a  recently  killed  warm-blooded 
animal.  Paul  Bert  obtained  a  tracing  of  the  contraction  of  non-striated 
muscle,  as  manifested  by  the  movement  of  the  walls  of  hollow  organs, 
containing  this  kind  of  tissue.     This  is  shown  in  Fig.  284. 

Marey  has  shown  that  the  contraction  of  non-striated  muscle  is  not 
made  up  of  a  series  of  smaller  contractions,  as  in  striated  muscle,  but 
is  one  single  contraction,  which  may  be  of  greater  or  less  duration. 
According  to  Engelmann,  a  stimulus  applied  to  a  group  of  non-striated 
fibres  is  propagated  to  neighbouring  fibres,  and  thus  the  stimulus  may 
radiate  in  various  directions,  even  in  tissues  containing  no  nerves.  The 
interesting  observations  of  Foster  and  Dew  Smith  on  the  contractions 
of  the  heart  of  a  snail,  and  of  G.  J.  Romanes  on  the  transmission  of 
impulses  in  the  bodies  of  Medusce,  support  the  statement.  Organs 
containing  non-striated  muscle  frequently  show  rhythmical  movements. 

1  As  to  the  hypertrophy  and  atrophy  of  muscle,  see  Wagner's  General  Patholo<jy, 
pp.  418-422, 


43()  THE  CONTRACTILE  TISSUE,^. 

It  is  difficult  to  estimate  experimentally  the  A\^oik  done  by  this  kind 
of  fibre,  but  when  Ave  considei-  the  force  of  the  bladder  in  expelling: 
urine,  and  still  more  the  force  of  the  uterus  in  parturition,  it  must 
evidently  be  very  great.  Nothing  definite  is  known  regarding  the  con- 
ditions of  fatigue.  According  to  Beaunis,  the  state  of  cadaveric  rigidity 
occiurs  to  a  slight  extent. 

In  ordinary  circumstances,  organs  composed  of  non-striated  muscle 
are  only  feebly  sensitive,  but  occasionally  they  become  so  sensitive  as- 
to  give  rise  to  ill-defined  sensations  of  discomfort,  or  even  of  ])ain. 

Regarding  the  general  physiology  of  muscular  tissue,  consult  Pkochaska — De 
Carne  Musculari  in  Oper.  Min.,  1800;  Bowman,  iu  Trans.  Roy.  Soc.  London. 
1840,  and  art.  Muscle,  in  Cyclop,  of  Anat.  and  Physiol.;  Todd  and  Bowman — 
Anat.  and  Phys. ;  and  Sharpev  and  Schafek,  in  Quain's  Anat.,  ninth  ed.,  vol, 
II.,  p.  llSe^se^. ;  Marey — Du  Mouvement  dans  les  Fonctions  de  la  Vie,  1868; 
Wundt's  Physiologie  Humaine,  p.  372  et  seq.;  Beaunis'  Physiologie  ;  for  full 
details  as  to  the  experimental  study  of  the  functions  of  muscle,  see  account  by 
Michaki.  Foster,  in  Handbook  for  the  Physiological  Laboratory,  p.  341  ;  also 
Cvox's  Methodik  der  Physiologischen  Experimente  und  Vivisectionen,  Fiinftes 
Capitel.  For  sketches  of  apparatus,  see  the  Atlas  of  the  same  work,  and  also 
Gscheidlen's  Physiologischen  Methodik ;  Marev'.s  Animal  Mechanism,  chaps. 
IV.,  v.,  and  VI.  As  to  the  production  of  heat  in  muscular  work,  see  Mattedcci 
— Sur  les  Phenomenes  Physiques  et  Chemiques  de  la  Contraction  Musculaire 
(Comptes  Rend.,  1856,  t.  XLII.) ;  J.  Beclard — De  la  Contraction  Musculaire 
dans  ses  raports  avec  la  Temperature  Animale  (Arch.  G^ner.  de  Med.,  1861,. 
5«  serie,  t.  XVII.  p.  24) ;  Heidenhain — Mechanische  Leistung,  Warmentwicklung 
und  Stoffumsatz  bei  der  Muskelthatigkeit,  Leipsig,  1864  ;  Wundt— Physique 
Medicale,  p.  535.  The  best  general  account  of  the  action  of  poisons  and  drugs  on 
muscle  is  to  be  found  in  T.  L.  Brunton's  Pharmacology,  Therapeutics,  and 
Materia  Medica,  chap.  V.  See  also  papers  by  Gerald  F.  Yeo  and  Thkodore. 
Cash,  on  the  relation  between  the  active  phases  of  contraction  and  the  latent 
period  of  skeletal  muscles.  Journal  of  Phydology,  vol.  iv.  No.  2;  and  H.  Kronecker 
and  W.  Stirling  on  the  Genesis  of  Tetanus,  Journal  of  Physiology,  vol.  i.  Nos.  4 
and  5. 


Chap.  XVIIL— THE  ELECTRICAL  PHENOMENA  OF  MUSCLE. 

"We  have  already  seen  that  when  the  stimulus  transmitted  by  a  motor 
nerve  reaches  a  muscle,  molecular  changes  of  a  chemical  character  are  set 
up  in  the  latter  which  result  in  the  production  of  motion,  of  heat,  of 
sound,  and  of  various  chemical  substances,  such  as  carbonic  acid,  para- 
lactic  acid,  etc.  One  would  naturally  expect  that  such  changes  would 
be  associated  wath  electrical  disturbances,  seeing  that  chemical  changes- 
are  so  often,  if  not  invariably,  linked  ynth.  electrical  phenomena.  The 
stages,  however,  by  which  the  existence  of  electrical  phenomena  in  living 
muscle  and  in  other  living  structures  has  been  satisfactorily  established 


THE  ELECTRICAL  PHENOMENA   OP  MUSCLE.  437 

forms  a  chapter  in  science  so  interesting  and  so  suggestive  that  I  shall 
now  place  a  short  account  of  them  before  the  reader,  and  gradually  lead 
him  to  our  present  position  with  regard  to  these  phenomena. 

The  discovery  of  animal  electricity  dates  from  1786.  It  is  said  that 
Madame  Galvani,  the  wife  of  Luigi  Galvani  (1737-1798),  in  preparing 
some  frogs  for  culinary  purposes,  observed  that  the  apparently  dead 
animals  became  convulsed  when  brought  into  the  neighbourhood  of  a 
frictional  electrical  machine  in  action.  Her  husband,  who  was  jjrofessor 
of  anatomy  and  physiology  in  Bologna,  had  his  attention  directed  to  these 
phenomena,  and  found  that  the  convulsions  occurred  at  the  instant  a 
spark  was  emitted  from  the  conductor,  provided  some  metallic  substance 
was  in  contact  with  the  nerve  of  the  frog.  He  tried  the  same  experiment 
with  lightning,  and,  in  the  autumn  of  the  same  year,  endeavoured  to 
discover  the  action  of  atmospheric  electricity  on  the  prepared  legs  of  a 
frog  when  the  sky  was  stormless.  On  the  20th  of  September,  he 
suspended  three  frogs  to  the  iron  trellis- work  surrounding  the  roof  of  his 
house,  by  means  of  copper  hooks,  and  saw,  when  they  were  blown  about 
by  the  wind,  that  convulsions  were  caused  whenever  they  came  in  con- 
tact with  the  iron.  This  observation  con^dnced  him  that  an  electrical 
machine  was  not  required,  the  same  effect  being  produced  on  the  contact 
of  dissimilar  metals.  He  at  length  concluded  that  the  convulsions  were 
<lue  to  inherent  electricity,  that  is,  electricity,  to  use  his  own  phrase, 
secreted  in  and  originating  from  the  animal  tissues.^ 

Galvani  published  an  account  of  his  experiments  in  1791.^  At  this 
time  the  existence  of  a  "  nervous  fluid,"  a  something  which,  if  not  life 
itself,  was  considered  inseparable  from  it,  was  keenly  debated  by  the 
learned,  and  contended  for  by  the  animists.  Galvani's  discovery,  there- 
fore, riveted  the  attention  of  the  scientific  world — electricity  took 
the  place  of  the  nervous  fluid,  and  the  source  of  life,  and  the 
origin  of  the  bodily  and  mental  functions  were  now  ascribed  to  the 
•existence  of  a  new  principle,  which,  from  the  name  of  its  discoverer,  was 
<;alled  Galvanism. 

Among  the  many  distinguished  men  whose  attention  was  attracted 
toward's  Galvani's  discovery,  the  most  remarkable  was  Alexander  Volta. 
He  was  a  physicist  and  professor  of  natui'al  philosophy  in  the  University 
of  Pavia.     At  first  he  entered  fully  into  the  views  of  his  countryman, 

^  Most  of  the  historical  portion  of  this  chapter  was  written  by  the  author  for 
Hughes  Bennett's  Text-book  of  Physiology  in  1871.  Assistance  was  also  derived 
from  a  paper  by  Dr.  M'Gregor-Ilobertson,  in  Proceedings  of  the  Philosophical 
Society  of  Glasgow,  vol.  13,  No.  2. 

^  These  results  were  communicated  to  the  Institute  of  Bologna  in  1791,  in  a  paper 
entitled  "Aloysii  Galvani  de  virihus  Electricitatis  in  motu  mtisciclari  commentarius.'' 


4:38  THE  CONTRACTILE  TJSSUE^S, 

and  repeated  his  experiments.  But  in  his  hands  galvanism,  instead  of 
taking  a  })hysiological  and  medical,  took  a  physical,  direction.  Finding 
that  muscular  contractions  in  a  frog  could  be  produced  ordy  hy  the  con- 
tact of  dissimilar  metals,  he  at  length  dissented  from  Galvani's  theory  of 
animal  electricity.  Trying  by  the  same  means  to  produce  muscidar 
contractions  in  the  human  body  he  failed.  But  on  placing  a  metal 
above  and  below  the  tongue,  he  detected  a  peculiar  taste  at  the  moment 
of  contact.  This  experiment  had  been  previously  recorded  by  Sulzer,. 
and  laid  aside  only  as  curious,  but  in  the  hands  of  Volta  it  became  the 
groundwork  of  chemical,  or  Avhat  has  been  called  Voltaic,  electricity. 
In  opposition  to  Galvani,  therefore,  he  put  forth  the  opinion  that  the 
muscular  contractions  in  the  frog  had  nothing  to  do  with  animal,  but. 
were  caused  by  a  very  feeble,  artificial,  electricity,  which  Avas  ])roduced 
by  the  application  of  heterogeneous  metals  to  the  limbs  of  the  animals. 

In  reply  to  this  attack,  Galvani  pointed  out  that  the  contractions- 
might  be  occasioned  bj'  one  metal ;  but  Yolta  then  showed  that  the  two- 
extremities  or  surfaces  of  one  piece  of  metal  might  be  in  different  states- 
of  tension,  and  therefore  capable  of  exciting  electricity.  Galvani  then 
used  mercury  alone,  to  which  this  objection  could  not  apply,  and  dipping, 
the  muscles  into  one  part  of  a  trough  filled  with  it,  he  thus  succeeded 
in  causing  contractions.  But  Volta,  by  a  new  series  of  experiments,, 
demonstrated  that  mercmy  was  always  altering  under  the  action  of  the 
air,  and  that,  in  conjunction  Avitli  moisture,  it  could  produce  electricity 
independently  of  an  animal.  It  now  became  necessary  for  Galvani  to- 
show  that  contractions  took  place  Avithout  any  metal  at  all,  and,  aided 
by  his  nephew  Aldini,  he  succeeded  in  doing  so,  and,  as  he  thought,  in 
for  ever  silencing  his  formidable  opponent.  In  fact,  he  discovered  that 
on  dissecting  out  the  sciatic  nerve  of  a  frog,  but  leaving  one  end  in  connec- 
tion with  the  leg,  and  bringing  this  nerve  in  contact  with  the  muscles- 
externally,  the  latter  were  thrown  into  distinct  contractions.  He  alsa 
caused  the  limb  to  contract  by  simply  bringing  the  nerve  in  contact 
with  the  muscle  of  another  animal,  which  was  insulated  from  the  limb  of 
the  frog. 

His  theory  of  animal  electricity  now  was,  that  it  was  produced  in  the 
nervous  system,  and  especially  in  the  cerebrum.  The  internal  substance 
of  nerves  he  considered  to  have  great  conducting  powers,  but  their  oily 
surfaces  prevented  dispersion  through  the  body,  and  allowed  its  accumu- 
lation in  the  muscles.  These  last  he  compared  to  a  Leyden  jar,  the 
outer  surface  being  negative,  the  inner  positive.  The  nerve  was- 
analogous  to  the  conductor  of  the  jar.  When  the  nerve  connects  the 
inner  with  the  outer  surface,  there  is  a  discharge  of  electricity,  causing; 
irritation  and  contraction  of  the  muscles. 


THE  ELECTRICAL  PHENOMENA  OF  MUSCLE.  439 

Yolta  at  first  endeavoured  to  meet  these  facts  by  the  supposition  of  a 
mechanical  stimulation  of  the  nerves,  but  at  length  showed  that,  if  not 
caused  by  metals,  it  was  necessary  that  there  should  be  dissimilar  fluids 
and  tissues  which  were  capable  of  exciting  electricity.  It  was  admitted, 
even  by  Galvani's  followers,  that  it  was  essential  to  the  success  of  the 
experiment  that  the  muscle  with  which  the  nerve  was  in  contact  should 
be  moistened  with  blood  or  some  thick  fluid,  and  if  by  any  accident  the 
limb  remained  motionless,  it  was  only  necessary,  in  order  to  induce 
muscular  contractions,  that  the  parts  to  be  in  contact  should  be  moistened 
with  saliva,  brine,  mucus,  etc.,  or  still  better,  with  soapy  water,  and  best 
of  all,  with  a  solution  of  acids  or  alkalies. 

Galvani,  in  several  letters  to  Spallanzani,  endeavoured  to  weaken  the 
force  of  these  arguments,  as  did  Humboldt,  who  showed  that  contrac- 
tions resulted  when  the  circuit  consisted  only  of  nerve  and  muscle, 
without  the  interposition  of  blood,  mucus,  etc.  About  this  time,  1798, 
Galvani  fell  ill,  and  died  on  the  4th  December  of  that  year.  Volta's 
experiments,  on  the  other  hand,  were  continued  with  unabated  energy, 
and,  towards  the  end  of  1799,  he  invented  the  Voltaic  pile,  whereby  his 
opinions  were  supported  and  the  production  of  electricity  by  the  contact 
of  metals  and  a  fluid  was  completely  proved.  This  great  victory,  which 
Galvani,  by  his  death,  escaped  the  mortification  of  witnessing,  notwith- 
standing the  opposition  of  Humboldt,  Aldini,  PfaflF,  and  a  few  others, 
overthrew  the  idea  of  an  animal  electricity  for  the  space  of  twenty- 
eight  years.  During  this  period,  indeed,  its  existence  was  generally 
regarded  with  incredulity,  and  the  term  animal  magnetism,  a  designation 
not  infrequently  adopted  by  impostors,  only  tended  to  bring  it  still  more 
into  contempt.  Volta  died  in  1826,  and  it  is  curious  that  only  a  year 
afterwards,  Nobili  again  revived  the  idea  of  animal  electricity,  by  de- 
monstrating the  existence  of  an  electrical  current  in  the  frog.  But  in 
the  interval  of  twenty-eight  years.  Voltaic  electricity  had  made  wonder- 
ful progress.  In  the  hands  of  Sir  Humphry  Davy,  it  led  to  brilliant 
discoveries  in  chemistry,  and  its  subsequent  practical  applications 
constitute  some  of  the  wonders  of  physical  science  in  the  present 
age. 

In  1820,  Oersted,  a  Danish  philosopher,  discovered  electro-magnetism. 
He  showed  that  when  a  continuous  galvanic  current  passes  along  a  Avire, 
placed  above  or  below,  and  parallel  to,  a  magnetic  needle,  the  latter  is 
immediately  deflected.  This  led  Ampere  to  invent  the  astatic  needle, 
and  in  turn  enabled  Nobili  to  construct  a  galvanometer,  which  he  ren- 
dered exquisitely  sensitive  by  various  improvements.  He  prepared  a 
frog  after  the  method  of  Galvani,  and  having  introduced  its  two  legs 
into  two  glasses  of  salt  water,  he  united  the  two  vessels  by  filaments 


440  TEE  CONTliACTILE  TISSUES. 

of  moist  cotton  :  the  frogs  muscles  at  once  contracted.  Removing 
the  cotton  he  connected  the  two  glasses  through  a  galvanometer 
circuit,  and  he  observed  a  deviation  of  from  10°  to  30°,  showing  that  an 
electrical  current  was  passing  from  the  feet  to  the  head  of  the  animal.  By 
introducing  several  frogs  into  the  circuit,  he  increased  the  strength  of 
the  current.  The  galvanometer  of  Nobili  enaljled  physiologists  to  de- 
monstrate that  Galvani  and  Volta  were  both  right  and  both  wrong, 
(lalvani  Avas  right  in  maintaining  the  existence  of  an  inherent  animal 
electricity,  whilst  he  was  Avrong  in  supposing  that  the  contact  of  two 
metals  with  the  tissues  gave  a  proof  of  this.  Volta,  again,  was  right  in 
maintaining  that  galvanism  could  be  produced  independently  of  animals, 
but  wrong  in  denying  that  electrical  currents  existed  in  them.  By  the 
astatic  needle,  as  Du  Bois-Reymond  happily  remarks,  metallic  electricity 
was  enabled  to  atone  for  the  wrong  she  had  done  to  her  more  tender 
t^vin  sister  in  their  earlier  years. 

While  Nobili,  by  his  construction  of  a  galvanometer,  was  of  such 
essential  service,  he  Avas  led  into  the  error  of  supposing  that  the  deflec- 
tion of  the  needle  was  due  to  thermo-electricity.  It  was  ten  years  later, 
in  1837,  that  Matteucci,  of  Pisa,  showed  that  to  obtain  a  deviation  of 
the  galvanometer  needle,  it  Avas  not  necessary  to  prepare  the  frog 
according  to  Galvani's  method.  On  connecting  any  two  parts  of  its 
body,  as,  for  example,  the  head  and  legs,  by  means  of  the  galvanometer, 
he  at  once  obtained  a  deviation.  In  1841,  he  advanced  the  folloAving 
law :  "  The  interior  of  a  muscle,  placed  in  connection  Avith  any  part 
Avhatever  of  the  same  animal,  such  as  nerve,  surface  of  muscle,  skin,  etc., 
produces  a  current  AA^hich  goes  in  the  animal  from  the  muscular  part 
to  that  which  is  not  so."  In  this  paper,  he  first  described  his  muscular 
pile,  consisting  of  about  tAventy  frogs'  thighs  roughly  cut  across,  and 
arranged  end  to  end.  On  connecting  the  stump  of  the  knee  Avith  one 
AA^re  leading  to  the  galvanometer,  and  the  section  of  the  femur  Avith  the 
other,  the  needle  AA^as  at  once  deflected  so  as  to  indicate  a  current 
passing  upwards  in  the  pile  from  the  knee  to  the  thigh.  He  considered 
this  to  be  a  current  different  from  the  frog  current  of  Nobili,  and  he 
held  that  the  frog  had  tAvo  currents  (1)  the  muscular  current  (Nobili's) 
common  to  all  animals ;  and  (2)  the  sjjecial  current,  evolved  by  the 
muscular  pile,  peculiar  to  the  frog. 

In  1841,  Professor  Emil  Du  Bois-Reymond,  of  Berlin,  repeated 
Matteucci's  experiments,  and  further  investigated  the  subject  Avith  the 
aid  of  most  delicate  galvanometers,  and  other  ingenious  apparatus 
constructed  by  himself.  From  this  period  a  neAv  impulse  Avas  given  to 
the  experimental  investigation  of  animal  electricity. 

For  the  purpose  of  indicating  the  current  Du  Bois-Reymond  used  a 


THE  ELECTRICAL  PHENOMENA   OF  MUSCLE. 


441 


IFiG.  285.— Magnet  of 
Wiedemann's  Galvano- 
tmeter,  shown  in  Fig. 
:286. 


Fia.  2S6. — Wiedemann's  Galvanometer  or  Boussole.i 


Fig.  287.— Du  Bois-Reymond's  arrangement  of  Hauy's  bar  for  rendering 
Wiedemann's  Boussole  astatic. 

^  A  view  of  a  better  and  more  modern  form  of  this  instrument  is 
shown  m  M'Gregor-Robertson's  Physiological  Physics,  Fig.  56,  p.  105, 
.and  an  excellent  account  is  given  of  the  instrument. 


442 


THE  CONTRACTILE  TISSUES. 


reflecting  galvanometer  of  extreme  sensibility,  whose  oscillations  were 
controlled  by  a  magnet  in  its  vicinity. 

Various  forms  of  galvanometers  may  be  employed  in  ex])eriments  re- 
lating to  animal  electricity.  The  most  useful  for  ordinary  jmrposes  of 
demonstration  are — 


1.  Wiedinnann^s  Gulcanometer  or  Bovf>soh,  shown  in  Fig.  286.      It  consists  of  a 
thick  copper  cylinder,  A  (Fig.  286),  in  the  interior  of  which  a  magnetized  ring 

(Fig.  285)  is  suspended  from  the  top  of  a  glass  tube  by  a 
single  filament  of  silk.  From  the  ring  A,  in  Fig.  288,  an 
aluminium  rod  passes  up  to  B,  a  frame  which  holds  a  circular 
plane  mirror.  Plugs  of  copper  are  used  to  close  up  the  ends- 
of  the  chamber  in  which  the  circular  magnet  swings,  whilst 
the  chamber  containing  the  mirror  (not  shown  in  Fig.  286, 
but  placed  a  little  above  A)  is  closed  by  a  brass  cover  canying 
a  thin  circular  piece  of  glass,  so  that  the  mirror  can  be  seen. 
On  each  side  of  A  (Fig.  286)  the  coils  of  wire  B  B  slide  in  a 
wide  slot  so  that  they  can  be  brought  close  to  or  even  over 
the  copper  chamber  A.  Each  coil  contains  about  30,000 
turns  of  very  fine  wire,  and  the  resistance  is  equal  to  7,000 
ohms  for  each  coil.^  The  copper  chamber  damps  the  oscilla- 
tions of  the  magnetic  ring,  because  the  oscillations  of  the 
latter  set  up  induction  currents  in  the  opposite  direction  in 
the  copper,  and  these  react  on  the  ring,  so  that  it  quickly 
comes  to  rest.  The  ring  magnet  (corresponding  to  the 
needle  in  an  ordinary  galvanometer)  is  rendered  astatic  by 
the  arrangement  shown  in  Fig.  287,  called  Haiiy's  bar.  It 
consists  of  an  accessory  magnet,  S  N,  placed  in  the  magnetic 
meridian,  and  therefore  parallel  to  the  needle.  Its  north 
pole  should  be  pointing  north,  as  is  that  of  the  needle.  It 
is  supported  on  the  bar  e  f,  which  is  in  the  same  direction 
as  the  axis  of  the  coils,  and  the  magnet  can  slide  up  and  down 
the  bar,  which  is  graduated  into  centimetres.  The  magnet 
may  be  moved  from  a  distance  by  the  cord  m  n,  passing  from 
the  wheel  k  to  the  arrangement  of  pulleys  1  c,  shown  in  the 
figure,  and  thus  the  oscillations  of  the  ring  magnet  are  qnite 
under  control.     An  image  of  a  scale  placed  in  front  of  the 

Galvanometer.    A,  Mag-    mirror  may  either  be  watched  by  the  observer  through  a 
net;  B,  mirror;  C,  hook  ■'  jo 

for  suspending  by  silk    short  focus  telescope,  or  a  lamp  may  be  placed  in  front  of 

the  mirror  so  that  a  beam  of  light  is  reflected  from  it  on  to 
a  scale  placed  at  a  suitable  distance.  The  advantage  of  this  instrument  is  that  it- 
is  practically  an  aperiodic  or  dead  heat  galvanometer,  that  is  to  say,  when  in- 
fluenced by  a  current,  the  magnet  swings  slowly  and  comes  to  rest  without  oscil- 
lation, and  when  the  current  is  withdrawn  it  swings  back  again  to  zero  and  then 
comes  to  rest. 

2.  Thomson's  Reflecting  Galvanometer. — The  other  form  of  galvanometer  is  Sir 

^  The  instrument  is  also  provided  with  two  coils  of  low  resistance,  1  ohm,  suit- 
able for  thermal  currents  (p.  421). 


Fig.    288.— Magnet    and 
mirror  of   Wiedemann's 


THE  ELECTRICAL  PHENOMENA  OF  MUSCLE. 


443 


William  Thomson's  reflecting  gal- 
vanometer, seen  in  Fig.  289,  an 
instrument  more  sensitive  than  the 
one  above  described  and  more  stiit- 
able  for  refined  investigations.  This 
instrument  is  upon  the  same  prin- 
ciple as  the  ordinary  galvanometer, 
but  it  is  modified  by  having  the 
needles  constituting  the  astatic 
system  very  short  and  very  light, 
by  having  the  coils  of  wire  in  the 
l)obbins  brought  as  close  to  the 
needles  as  possible,  and  by  having 
a  small  silvered  mirror  attached 
to  the  uppermost  group  of  needles. 
A  lamp  is  placed  in  front  of  the 
little  mirror,  and  a  ray  of  light  is 
reflected  by  the  mirror  iipon  a 
scale  placed  at  a  convenient  dis- 
tance in  front  of  the  instrument. 
The  galvanometer  made  for  phy- 
siological purposes  has  a  resistance 
of  8,498  ohms  at  18°  C.  One 
Daniell's  element  gives  through  a 
circuit  of  254,970,000  ohms  resist- 
ance a  deflection  of  130  divisions 
on  the  scale,  and  throvigh  a 
resistance  of  33,146  meg-ohms^  a 
deflection     of     1    division.       It    is   F'O-    2S9.-Reflecting    galvanometer    of    Sir    William 

Thomson,    a,  Upper,  and  b,  lower  bobbm  of  nne  wire  ; 
therefore  an   instrument   of   great  a  small  mirror  is  attached  to  the  upper  group  of  mag- 

„•+„„„„    „„j    „f     Q-,7+„QTv,Q     ^qK     netic  needles  in  the  centre  of  (t;  c,  brass  rod,  bearing  d, 

resistance   and   of    extreme    deli-  ^  ^^^^^^^  ^^^^^^  ^^^  regulating  the  position  of  the 
cacy.  needles  underneath  ;  e  e  e  e,  binding  screws. 

3.  Lippmann's  Capillary  Electrometer.  The  action  of  the  substances  set  free  at 
the  electrodes  in  electrolytic  decomposition,  and  the  energy  shown  as  motion  in 
these  circumstances,  are  strikingly  manifested  by  the  behaviour  of  a  drop  of  mer- 
cury in  dilute  sulphuric  acid,  when  the  positive  pole  of  a  battery  is  put  La  con- 
nection with  the  mercury  and  the  negative  dips  into  the  acid.  The  mercury  extends 
towards  the  negative  electrode  during  the  passage  of  the  current,  becoming  covered 
with  a  film  of  sub-oxide,  which  dissolves  in  the  acid,  leaving  a  bright  surface. 
By  making  and  breaking  the  current  a  series  of  oscillations  is  set  up.  Movements 
in  the  mercurial  electrode  and  adjacent  acid  have  been  observed  by  many  phj'sicists, 
and  have  received  various  explanations.  Erman,  in  1809,  was  the  first  to  observe 
that  when  a  drop  of  mercury  was  placed  on  a  grooved  surface  between  the 
electrodes  it  moved  towards  the  negative  pole  ;  and  he  also  observed  that  "  a  drop 
of  mercury  in  a  horizontal  tube,  with  dilute  acid  on  both  sides,  moved  at  the 
passage  of  the  electric  current  through  the  tube  toward  the  negative  electrode."- 

.     1 A  meg-ohm  =  1,000,000  ohms. 

2  For  an  historical  account  of  this  subject,  see  Lippmann,  Annale'<  de  Chemie  et 
de  Physique,  1875,  p.  540. 


444 


THE  CONTRACTILE  TISSUES. 


This  latter  phenomenon  was  fully  investigated  by  Lippmann,*  aiul  led,  along  with 
researches  by  Quincke,  not  only  to  a  theoretical  explanation  of  electro-capillary 
action,  but  also  to  the  construction  of  the  capillary  electrometer.  It  is  now  known 
that  these  phenomena,  both  as  seen  in  the  experiment  with  the  globule  of 
mercury  and  in  the  capillary  tube,  are  due  to  a  change  in  the  surface  tension  pro- 
duced by  the  electrical  polarization  of  the  surface  of  tlie  mercury. 

Lippmann's  form  of  the  electrometer,  shown  in  Fig.  290,  consists  of  a  tube  of 
•ordinary  glass,  A,  1  metre  long  and  7  millimetres  in  diameter,  open  at  both  ends, 
and  kept  in  the  vertical  position  by  a  stout  support.  The  lower  end  is  drawn  to 
a  capillary  point,  until  the  diameter  of  the  capillary  is  '005  of  a  millimetre.  The 
tube  is  filled  with  mercury,  and  the  capillary  point  is  immersed  in  dilute  sulphuric 
acid  (1  to  6  of  water  in  volume),  and  in  the  bottom  of  the  vessel,  B,  containing  the 


Fig.  2P0.— Lippmann's  Capillary  Electrometer. 

acid  there  is  a  little  more  mercury.      A  platinum  wire,  a,  is  put  into  connection 
with  the  straight  tube  having  the  capillary  point,  and  another  platinum  wire,  )3, 

^  Lippmann,  Comptt.-i  Rendus,  1873,  p.  1407  ;  Annal.  de  Chem.  et  dt  Phys.  op.  cit, 
p.  494  ;  Poggendorf's  Annahn,  cxlix.  p.  547  ;  also  Phil.  Mag.  [4],  xlvii.  p.  281. 


THE  ELECTRICAL  PHENOMENA  OF  MUSCLE.  445 

enters  the  wide  tube,  B.  Finally,  arrangements  are  made  by  which  the  capillary 
point  can  be  seen  with  a  microscope,  M,  magnifying 
250  diameters.  The  appearance  of  the  tube  under 
the  microscope  is  shown  in  Fig.  291.  Such  an  in- 
strument is  very  sensitive  ;  and  Lippmann  states 
that  it  is  possible  to  determine  a  difference  of 
potential  so  small  as  that  of  the  tttJttt  of  a  Daniell. 
Lippmann  made  use  of  the  arrangement  shown  in 
Fig.  290  for  bringing  back  the  mercury  to  the  zero- 
point  when  it  had  been  pushed  up  the  capillary  tube 
by  the  action  of  a  constant  electro-motive  force  in 
the  direction  of  j3  to  a,  and  for  measuring  by  means        ^ig.  291.— Appearance  of  the 

of  a  manometer,  H,  the  pressure  in  mm.  of  mercury        capillary  tube  in  Lippmann's 

.  electrometer, 

required  to  bring  the  mercury  back.  In  the  appar- 
atus, T  is  an  India-rubber  bag  or  tube  capable  of  being  compressed  between  plates- 
approximated  by  the  screw  E,  so  that  pressure  is  exerted  on  the  upper  end 
of  the  long  vertical  tube,  and  the  amount  of  this  pressiire  is  measured  in  mm.  of 
mercury  by  the  manometer,  H.  Various  simpler  forms  of  the  capillary  electro- 
meter can  be  easily  made,  in  which  the  capillary  tube  rests  in  the  horizontal 
position  on  the  stage  of  the  microscope,  and  in  which,  also,  the  tube  may  be  so' 
fine  as  to  bear  examination  with  a  magnifying  power  of  400  diameters.^ 

The  special  value  of  the  capillary  electrometer  lies  in  the  quichiess  with  luhicJi  it 
responds  to  any  sudden  variation  in  the  e.  m.  f.  As  observed  by  Burdon-Sanderson,. 
with  reference  to  changes  in  potential  in  the  injured  heart  of  the  frog  while  alive,, 
it  is  striking  to  notice  "  that  the  movements  of  the  mercurial  column  not  only 
correspond  closely  in  time  to  the  actual  changes  which  they  represent,  but  express^ 
with  very  great  accuracy  the  difi"erences  of  potential  which  actually  exist  in  each 
successive  phase  of  a  variation."  The  oscillations  of  the  column  of  mercury  in  the 
capillary  tube  may  be  photographed  on  a  moving  sensitive  plate,  when  a  picture 
such  as  is  seen  in  Fig.  292  will  be  obtained,  which  shows  at  a  glance  gradual  or 
sudden  changes  in  potential. - 


Fig.  292. — Changes  in  potential  caused  by  the  induction  currents  from  the  secondary  coil 
of  an  inductorium  at  the  moments  of  closing,  c  ;  and  of  opening,  r  ;  r,  the  primary  cur- 
rent. From  a  photograph  by  Marey  of  the  oscillations  of  the  mercury  in  the  capillary 
tube  of  Lippmann's  electrometer. 

4.    The  Telephone.     By  this  instrument  sounds  may  be  heard  on  making  and 

^  See  author's  paper  on  Lippmann's  capillary  electrometer,  Proceedings  of  the 
Philosophical  Society  of  Glasgow,  vol.  xiv.  p.  37  ;  Burdon-Sandersou,  on  the 
electromotive  properties  of  the  leaf  of  Dionsea  in  the  excited  and  unexcited  states, 
Phil.  Trans,  part  i.  1882  ;  Loven,  Nordiskt  Medic.  Arkiv.  vol.  xi.  No.  14.  As 
to  a  form  made  by  Prof.  Dewar,  see  S.  P.  Thomson's  work  on  Electricity. 

-  Thus  Burdon-Sanderson  has  photographed  the  oscillations  caused  by  changes- 
of  potential  in  Dionsea  and  in  the  frog's  heart.  Royal  Institiition  Lecture,  1882. 


446 


THE  CONTRACTILE  TISSUES. 


breaking  the  current  from  a  muscle  at  rest.  The  current  shown  by  a  muscle  in 
-iction  cannot  be  so  detected.  The  telephone  has  not  been  of  any  special  service  in 
the  investigations  of  currents  from  animal  tissues. 

Method  of  Making  Experiments  with  Galvanometer. — The  very  sen- 
sitiveness of  the  galvanometer  is  one  of  its  chief  sources  of  error.  If 
the  ends  of  the  galvanometer  wires  are  connected  with  two  wires,  say  of 
copper,  the  ends  of  which  are  immersed  in  a  conducting  fluid,  a  deflec- 
tion of  the  needle  at  once  indicates  a  powerful  current,  because  the  two 
wires  are  not  in  an  absolutely  similar  electrical  state  ;  or  if  the  wires  are 
•directly  connected  with  the  tissue  to  be  examined,  another  powerful 
deflection  occurs,  because  electricity  is  evolved  at  the  point  of  contact 
of  the  Avires  and  the  moist  tissue. 

Further,  if  metallic  conductors,  say  composed  of  zinc,  coming  from 
the  galvanometer,  were  brought  into  connection  with  living  muscle, 
little  or  no  current  Avould  be  obtained,  and  even  if  there  were  a  current, 
it  might  be  due  to  contact  of  the  metallic  conductors  Avith  the  living 
tissue  exciting  electrolytic  decomposition.  Hence  it  is  necessary  to  have 
.a  fluid  interposed  between  the  metal  and  the  animal  tissue,  as,  for 
•example,  the  zinc  "wire  or  plate  forming  the  terminals  of  the  galvano- 
meter must  be  immersed  in  a  saturated  solution  of  sulphate  of  zinc. 
But  as  sulphate  of  zinc  solution  would  have  the  eff"ect  of  irritating  the 
living  muscle,  it  is  necessary  to  have  an  inactive  substance  between  the 
tissue  and  the  sulphate  of  zinc  solution.  All  these  conditions  are 
fulfllled  by  the  arrangement  of  Du  Bois-Reymond,  which  is  that  usually 

employed,  and  which  may  conveniently  be 
termed  the  non-polarizable  electrodes.  Many 
modifications  of  this  apparatus  have,  from 
time  to  time,  been  emjDloyed  for  particular 
purposes,  but  the  form  most  convenient  for 
demonstrating  the  principal  electrical  j^heno- 
mena  of  nerve  and  muscle  is  what  is  here 
described.  It  consists  (Fig.  293)  of  two 
troughs  made  of  zinc,  mounted  on  insulating 
plates  of  vulcanite.  The  inner  surfaces  of  the 
troughs  are  carefully  amalgamated,  and  they 
are  filled  nearly  full  of  a  saturated  solution  of 
sulphate  of  zinc.  Into  each  trough  is  then 
placed  a  small  cushion  of  clean  blotting  or 
rfilter  paper,  Avhich  Cjuickly  becomes  permeated  by  the  solution. 
Finally,  a  small  thin  film  or  plate  of  sculptor's  clay,  or  kaolin,  moistened 
with  a  half  per  cent,  solution  of  common  salt,  or  still  better,  with  saliva, 
is  laid  on  each  paper  pad.     These  clay-pads  are  for  guarding  the  tissue 


T'lG.  203. — Non-polarizable  elec- 
trode of  Du  Bois-Reymond.  c, 
zinc  trough  ;  v,  vulcanite  base ; 
s,  vulcanite  shield  to  keep  pad 
6  of  blotting  paper  in  position  ; 
p,  moist  clay ;  </,  handle,  at  end 
of  which  there  is  a  vulcanite 
knob  ;  k,  binding  screw. 


THE  ELECTRICAL  PHENOMENA  OF  MUSCLE. 


447 


from  the  irritant  action  of  the  sulphate  of  zinc.     Wires  are  conducted 
from  the  trough  to  the  galvanometer,  as  shown  in  Fig.  294,  and  it  is 


Fig.  294. — Diagram  of  arrangement  of  Du  Bois-Reymond.  a,  a, 
zinc  troughs  ;  b,  vulcanite;  c,  paper  pads  ;  d,  e,  moist  clay;  /, /, 
binding  screws  for  terminals  of  galvanometer  ;  g,  observe  the  bit 
of  paper  conducting  d  and  e,  thus  completing  the  circuit. 

convenient  to  have  a  key  interposed  in  the  circuit,  so  that  any  current 
from  the  troughs  may  be  j^ermitted  to  pass  to  the  galvanometer,  or  be 
shut  off  at  pleasure.  It  is  essential  that  no  currents  are  derived  from 
the  troughs  or  from  any  of  their  connections,  that  is,  to  have  the  appar- 
atus non-polarizable.  This  can  be  done  by  taking  extreme  care  in  all 
the  arrangements,  and  by  connecting  the  troughs  for  a  few  hours  before 
the  experiment  by  a  thick  copper  wire  (passing  from  /  to  /),  and  laying 
a  morsel  of  moist  blotting  paper  from  one  paper  cushion  to  the  other  so 
as  to  place  the  troughs  in  circuit. 

To  determine  in  what  direction  that  current  may  be,  a  preliminary 
observation  is  necessary.  To  one  wire  of  the  galvanometer  a  piece  of 
zinc  is  bound,  and  to  the  other  a  piece  of  copper.  The  two  being 
placed  in  circuit,  a  current  is  produced,  and  the  beam  of  light  moves  in 
a  particular  direction.  The  copper  pole  being  positive  to  the  zinc,  one  can 
find  in  which  direction  the  beam  of  light  will  move  if  a  particular  wire 
is  positive.  The  non-polarizable  electrode  to  which  this  wire  is  con- 
nected is  carefully  noted,  and  one  can  then  always  tell  in  which  direction 
the  needle  must  swing  if  this  be  the  positive  electrode.  Into  the  circuit 
of  the  electrode  and  galvanometer  is  placed  a  small  resistance  box  or 
shunt,  graduated  for  the  particular  galvanometer  used.  It  is  so  inter- 
posed that  one  of  the  brass  plugs  may  be  placed  in  one  of  four  different 
positions.     If  in  one,  the  current  is  short-circuited,  and  none  can  pass 


448  THE  CONTRACTILE  TISSUES. 

to  the  galvanometei" ;  if  in  another,  a  10th  })art  of  the  total  amount  of 
current  is  allowed  to  pass;  or  in  other  positions,  100th  or  1000th — the 
remainder  being  returned  to  the  electrodes.     With  the  aid  of  such  an 
arrangement,  Du  Bois-Keymond  obtained  a  current  from  the  inactive 
muscle  of  the  frog  equal  to  from  0"035  to  0'075  of  a  Daniell.     This 
maximum  effect  was  obtained  when  a  muscle  of  the  frog,  one  with  as- 
parallel  fibres  as  possible  (sartorius  or  gracilis,  Fig.  203,  .s;,  p.  355),  was 
removed  fi'om  the  body,  and  so  placed  on  the  electi'odes  that  one  clay  pad 
touched  the  centre  of  the  longitudinal  surface  and  the  other  the  centre 
of  a  carefully-made  transverse  section.     This  current  is  directed  in  the 
muscle  from  the  transverse  section  toAvards  the  longitudinal  surface — ■ 
that  is  to  say,  it  passes  out  of  the  muscle  by  the  longitudinal  surface 
and  retiu'ns  to  the  transverse  section.     Hence  the  rule  formulated  is — 
The  longihidinal  surface  is  positive  to  the  transverse  section,  tvhich  is  negative. 
A  point  in  the  equator  of  the  longitudinal  surface  is  most  positive,  the 
axis  of  the  transverse  section  is  most  negative.     As  you  proceed  from 
the  equator  towards  either  end  of  the  surface  the  positivity  diminishes, 
and  as  you  proceed  from  the  axis  of  the  section  toAvards  the  circum- 
ference the  negati\aty  diminishes.     To  put  this  in  another  way — On 
the  longitudinal  surface,  a  point  at  a  distance  from  the  equator  is  negative  to 
a  point  nearer  to  it ;  on  the  transverse  section,  a  point  at  a  distance  from  the 
axis  is  positive  to  a  p)oint  nearer  to  it.     If  tAvo  points  are  taken  on  the 
longitudinal  surface  of  a  regularly-formed  muscle,  one  on  either  side  of 
the  equator,  and  both  equidistant  from  it,  these  tAvo  points  are  iso- 
electrical,  that  is  of  equal  potential,  and  shoAv  no  current,  and  similarly 
with  tAvo  points  on  the  cross  section  equidistant  from  the  axis.     Fresh 
cross  sections  may  be  made,  and  fresh  longitudinal  surfaces  may  be 
formed,  still  the  muscle  cylinder  exhibits  the  same  phenomena,  and 
that  AA'hether  the  siu-faces  haA'e  been  formed  by  cutting,  heating,  the  action 
of  acids,  or  simply  b}^  drying  the  exposed  surface.     In  the  last  case, 
the   layer   of  dead  tissue  on  the  surface  acts  as  an  indifferent   con- 
ductor, and  leads  the  current  produced  in  the  liA'ing  portions  beneath  it. 
In  the  case  Avhere  the  cross  section  has  been  made  obliquely,  Du  Bois- 
Reymond  showed  that  the  greatest  positive  tension  is  toAA^ards  the  obtuse 
angle,  the  most  negatiA'e  point  towards  the  acute  angle — i.e.  a  point  in 
the  neighbourhood  of  the  obtuse  angle  is  positive  to  a  point  in  the 
neighbourhood  of  the  acute  angle,  eA^en  though  both  are  equidistant 
from  the  equator.      These  haA-e  been    called    "inclination   currents." 
The  relative  electrical  condition  of  different  points  is  best  iuA'estigated 
by  a  modification  of  the  non-polarized  electrodes  made  by  Du  Bois- 
Reymond  himself.     A  flattened  tube  of  glass,  r  (Fig.  295),  contains  a 
slip  of  amalgamated  zinc.    The  end  of  the  tube  is  closed  by  a  moistened 


TEE  ELECTRICAL  PHENOMENA  OF  M  USCLE. 


449 


piece  of  clay,  tlie  part  projecting  from  the  tube  being  pressed  to  a 
point  t,  and  the  tube  is  then  filled  "with  zinc  solution.  The  zinc  is 
fastened  to  a  brass  support,  to  which  a  wire  is  led  (Fig.  295). 


FrG.  295. — Non-polarizable  electrodes.     For  description,  see  text. 

See  also  the  non-polarizable  electrodes  of  the  form  used  by  Burdon-Sanderson 
in  Fig.  230,  p.  380.  Another  form  which  may  be  used  for  stimulating  proto- 
plasmic bodies  under  the  microscope  by  non-polarizing  currents,  or  for  leading 
currents  from  such  microscopical  structures  to  a  capillary  electrometer,  is  shown 
in  Fig.  296. 


Fig.  296. — Engelmann's  nnn-polarizable  electrodes  for  use  on  the  stage  of  the 
microscope,  a  a,  grooves  in  glass  slide,  with  holes  in  d  e,  into  which  glass 
tubes,  h  c,  tightly  fit ;  /  g,  tubes  containing  salt  solution,  or  saturated  solution 
of  sulphate  of  zinc  ;  b  c,  pads  of  paper  :  n  o,  zinc  rods  ;  m,  cover  glass  ;  /, 
glass  on  which  object  is  placed.  The  space  between  m  and  I  communicates 
with  b  and  c. 

The  fine  clay  points  can  then  be  placed  on  any  desired  part  of  the 
muscle.  As  the  muscle  preparation  slowly  dies,  the  amount  of  current 
diminishes,  till,  on  the  advent  of  rigor,  it  disappears.  In  regard  to 
temperature,  freezing  and  a  high  temperature  also  abolish  it,  but  with 
moderate  degrees  of  heat  it  increases. 

Differences  of  temperature  produce  specially  strong  currents,^  a 
warmer  part  being  positive  to  a  colder,  the  difference  between  the  two 
connected  points  being  alone  influential,  and  the  condition  of  the  parts 
lying  between  being  unimportant. 

A  method  of  accurately  determining  the  amount  of  cuiTent  obtained 
from  muscle  or  other  tissue  was  devised  by  PoggendorfF.     An  improved 

1  Hermann,  Handhuch  der  Physiologie,  1S79,  Bd.  I.  Th.  I.  s.  196. 

I.  2  F 


450 


THE  CUSTLIACTILE  TISSUES. 


form  of  the  arrangement,  by  Dn  Bois-Reymond,  is  shown  in  the  accom- 
panying diagram,  Fig.  297. 

The  idea  of  the  arrangement  is  to  send  throngh  the  galvanometer,  B, 
the  maximnm  strength  of  current  obtained  from  the  tissue  M,  placed 
on  the  electrodes,  T,  and  then  to  send  from  a  Daniell's  cell,  K,  hut  in  an 
opposite  direction,  a  jDortion  of  current  sufficient  to  counterbalance  the 
tissue  current.  The  needle  is  thus  sulijected  to  two  forces,  equal  in 
amount  but  opposite  in  direction,  and  it  therefore  swings  back  to  zero, 
its  remaining  there  indicating  the  balance  of  the  two  forces.  By  the 
arrangement  the  amount  of  current  from  the  Daniell  employed  can  lie 
regulated  at  will,  and  can  be  exactly  estimated.  It  therefore  becomes 
a  measure  of  the  force  it  counteracts.  This  is  called  the  compensation 
method. 

From  the  Daniell,  K,  wires  proceed  to  the  binding  screw  a  and  h  at 
each  end  of  the  long  compensator,  which  consists  of  a  stretch  of  platinum 
ware  of  uniform  thickness.  A  slider,  bearing  a  platinum  point,  c,  to 
make  contact,  is  movable  ujd  and  down  the  wire.  From  one  binding 
screw  of  the  compensator  a  wire  proceeds  to  one  terminal  of  the  gal- 
vanometer, through  a  commutator,  C,  the  other  terminal  being  con- 
nected with  the  slider  also  through  the  commutator.^ 

The  Daniell  cell  and  the  platinum  Avire  of  the  compensator  may  be 
considered  as  the  main  circuit,  and  the  galvanometer  circuit  as  a  branch 
from  it.  The  current  from  the  Daniell  may,  therefore,  pass  straight 
along  the  compensator  and  Ijack  to  the  cell,  or  a  portion  may  start  from 

the  binding  screw,  a,  go  through  the 
galvanometer,  and  regain  the  com 
pensator  by  the  connection  with  the 
slider  at  c.  The  strength  of  this 
portion  will  depend  on  the  resist- 
ance in  the  branch  circuit.  By 
varying  the  position  of  the  slider, 
the  relative  amounts  of  resistance  in 
the  two  circuits  are  altered,  and  so 
a  stronger  or  weaker  current  can  be 
sent  through  the  galvanometer  from 
the  Daniell,  according  as  the  slider 
is  nearer  h  or  a. 

The  distance  betAveen  a  and  c  is 
read  off  by  means  of  a  millimetre  scale  placed  beneath  the  platinum 
wire,  and  since  the  wire  is  of  uniform  thickness  throughout,  a  c  is  a 

^  A  ver}'^  convenient  form  of  long  compensator,  with  resistance  coils,  is  made  by 
Messrs.  Elliot  Brothers,  London. 


Fig.  297. — Arrangement  for  measuring  the 
e.  m.  f.  of  a  section  of  muscle. 


THE  ELECTRICAL  PHENOMENA  OF  MUSCLE. 


451 


nieasui'e  of  the  resistance,  and  therefore  a  measure  of  the  amount  of  cur- 
rent sent  through  the  galvanometer.  By  means  of  the  commutator  the 
Daniel!  current  can  be  sent  through  the  galvanometer  in  one  direction 
■or  another.  Thus  a  current  from  the  Daniell,  whose  amount  can  be 
measured,  can  be  sent  through  the  galvanometer  equal  in  amount  and 
opposite  in  direction  to  the  current  from  the  muscle,  the  one  compen- 
■satina;  for  the  other. 


In  experiments  on  the  electromotive  properties  of  muscle  and  nerve,  it  is 
necessary  to  have  a  convenient  form  of  apparatus  by  which  resistance  can  be 
introduced  into  electrical  circuits.  One  of  the  most  convenient  instruments  for 
physiological  purposes  is  the  rheochord  of  Du  Bois-Reymond,  shown  in  Fig.  298. 


Fig.  '20S. — Rheochord  of  Du  Bois-Reiinond. 

It  consists  of  a  long  thin  box  containing  lengths  of  German  silver  wire,  I,  I,  II, 
V,  and  X,  the  ends  of  which  are  attached  to  brass  plates,  1,  2,  3,  4,  5,  6,  on  one 
•end  of  the  upper  surface  of  the  lid  of  the  box.  Each  of  these  brass  plates  maj' 
be  brought  into  electrical  contact  wath  the  next  one,  by  inserting  a  cylindrical 
brass  plug  in  the  semi-circular  holes  between  the  plates.  Further,  from  the  first 
plate  s,  a  platinum  wire  h,  1  metre  long,  runs  to  a  peg  W,  passing  over  an  ivory  knife 
edge  a.  From  the  next  brass  plate  l-s-,  another  wire  c  runsto^W.  Running  along 
the  side  of  the  instrument  there  is  a  platform  Z,  carrying  two  steel  cylinders  filled 
with  mercury,  and  closed  at  the  broad  ends  with  small  corks.  The  platinum 
wires  pass  through  these  cylinders,  and,  as  the  latter  touch  each  other,  a  greater 
or  less  length  of  platinum  wire  can  be  thrown  into  the  circuit,  according  to  the 
position  of  the  slider  Z.  The  wires  I  and  I,  between  1  and  2  and  2  and  .3,  have 
the  same  resistance  as  the  platinum  wires,  if  Z  be  passed  as  far  as  a  ;  the  wire  II 
has  double,  the  wire  v  has  five  times,  and  the  wire  X  ten  times  the  resistance  of 
the  full  length  of  the  platinum  wires.  Suppose,  now,  a  current  entering  at  P,  if 
Z  be  pushed  up  to  the  left  as  far  as  it  will  go,  and  if  a  brass  plug  have  been  intro 
duced  between  each  pair  of  brass  plates,  the  current  will  meet  with  no  resistance, 
and  it  will  pass  straight  across  the  brass  plates  to  Q,  and  thence  back  to  the  bat- 
tery. It  will  be  seen,  however,  that  by  pushing  the  slider  Z  to  the  right,  when 
the  current  reaches  s,  it  will  pass  up  the  first  platinum  wire  to  the  steel  bottl 
through  which  it  passes,  thence  to  the  adjoining  steel  bottle,  and  thence  back  to 
the  plate  Is,  by  the  other  platinum  wire.  Resistance  has  thus  been  introduced. 
This  may  be  increased  by  taking  out  the  plug  between  la  and  2,  when  the  cun-ent 


452  THE  CONTRACTILE  TISSUES. 

must  pass  along  the  loop  of  silver  wire  I,  then,  by  taking  out  the  plug  between 
2  and  3,  along  the  loop  I,  and  so  on,  with  reference  to  the  other  loops.  If  the 
steel  bottles  are  pushed  up  to  a,  and  if  all  the  plugs  are  out,  then  the  maximum 
amount  of  resistance  has  been  introduced.  In  using  the  instrument  practically,  it 
is  always  introduced  in  short  circuit — that  is  to  say,  two  wires  are  connected  with 
P  and  two  with  Q.  One  pair  of  wires  is  connected  with  the  circuit  of  the  bat- 
tery, and  the  other  pair,  we  will  suppose,  with  the  galvanometer  circuit.  By 
throwing  resistance  into  the  battery  circuit,  more  current  will  pass  to  the  galvano- 
meter circuit,  and,  on  the  other  hand,  if  the  resistance  in  the  battery  circuit  be 
very  small,  very  little  of  the  current,  if  any,  will  pass  through  the  galvanometer. 

The  observations  made  by  Dii  Bois-Eeymond,  already  mentioned,  are 
seen  in  reefing  muscle — that  is  to  say,  in  living  muscle  in  an  inactive 
state.  If  the  muscle  has  been  prepared  Anth  the  nerve  attached,  and  if 
the  nerve  is  stimulated  so  as  to  tetanize  the  muscle,  an  apparent  diminu- 
tion in  the  muscle  ciu-rent  is  observed,  and  the  needle  swings  back  a 
considerable  distance.  Sometimes  the  dimin\ition  is  equal  to  40  per 
cent,  of  the  original  current.  This  is  called  the  negative  variation  of 
the  muscle  current.  If  the  tetanus  is  continued  the  diminution  becomes 
less  marked.  On  its  cessation  the  needle  swings  back,  but  never  quite 
up  to  its  original  position  when  the  current  of  the  resting  muscle 
aflected  it. 

It  has  been  ascertained  by  most  refined  methods  of  investigation, 
conducted  by  Von  Helmholtz,  that  the  commencement  of  negative 
variation  is  about  the  -^~  of  a  second  after  the  moment  of  the  excita- 
tion of  the  nerve.  But  Yon  Bezold  showed  that  in  the  nerve  itself 
there  elapses  about  the  -o^„  of  a  second  between  the  instant  when  the 
excitant  is  apjjlied  to  the  nerve  and  when  the  nerve  is  excited.  Con- 
sequently, the  commencement  of  the  negative  variation  of  the  muscle 
current  coincides  exactly  with  the  moment  of  the  excitation  of  the 
muscle.  The  negative  variation,  which  first  increases  and  then  de- 
creases, lasts  about  the  ^—^  of  a  second,  and  it  is  entirely  gone  before 
the  muscle  begins  to  contract — that  is  to  say,  it  occurs  during  a  portion 
of  the  period  of  latent  stimulation.  (See  p.  406.)  Bernstein  arrived 
at  the  conclusion  that  the  negative  variation  travels  with  a  rapidity  of 
about  3  metres  per  second,  which  is  the  same  rate  as  that  of  the  Avave 
of  muscular  contraction.  This  he  was  able  to  do  by  a  mode  of  experi- 
ment suggested  by  the  observations  of  Matteucci,  Yon  Helmholtz,  and 
others. 

Matteucci  was  the  first  to  observe  that  if  the  sciatic  nerve  of  one  prepared  limb- 
of  a  frog  (Fig.  300),  which  we  will  call  A ,  is  placed  over  the  muscles  of  a  similar 
limb,  which  we  will  term  B,  when  B  is  excited  to  contraction,  A  also  immediately 
contracts  ;  at  all  events,  the  contraction  of  A  occurs  apparently  at  the  same  time 
as  the  contraction  of  B.  This  phenomenon  is  termed  ^latleucci'n  indvctd  contractioiu 


THE  ELECTRICAL  PHENOMENA  OF  MUSCLE. 


453 


The  arrangement  is  shown  in  Fig.  300,  or  the  experiment  may  be  demonstrated 
±0  a  class  by  the  method  illustrated  in  Fig.  299. 


rY-\  £ 


riG.  299. — Arrangement  to  show  Matteucci's  induced  con- 
traction. Fl,  F2,  muscle  telegraphs ;  Fl.  connected  with 
muscle  r/il  and  F2  with  mi.  Current  from  inductorium  sent 
through  //il,  over  which  the  nerve  of  lai  has  been  laid.  When 
tn\  contracts,  mi  also,  and  apparently  simultaneously,  con- 
tracts, and  the  two  signals  are  moved.  II,  Secondary  coil 
at  a  distance  from  I,  the  primarj'.  In  circuit  of  I  is  a  voltaic 
<;ell,  with  a  key  at  X.  By  opening  and  closing  the  key  X, 
single  shock.s  are  obtained  from  II.  II,  with  dotted  outline, 
is  the  secondary  coil  brought  nearer  to  I,  the  primary. 


Fig.  300. — Arrangement  of  limhs 
to  show  Matteucci's  induced  con- 
traction. 


The  explan  ation  is  that  the  negative  variation  current  related  to  the  conti'action 
•of  B  (Fig.  300)  irritates  the  nerve  of  A.,  and  consequently  A  also  contracts. 

Von  Helmholtz,  in  his  earlier  studies  of  muscle,  observed  that  the  contraction 
of  the  second  muscle  {A  in  Fig.  300,  and  to2  in  Fig.  299)  occurred  about  the 
middle  of  the  latent  ptr'iod  of  the  first  {B  in  Fig.  300,  and  ml  in  Fig.  299).  This 
observation  was  repeated  by  Von  Bezold  with  the  artifice  of  causing  both  muscles 
to  record  their  curves  on  a  quickly  rotating  cylinder,  and  he  showed  in  this  way 
that  the  contraction  of  A  took  place  about  the  beginning  of  the  latent  period  of  B. 
Holmgren,  bj'  another  method,  observed  fluctuations  in  the  negative  variation 
■current.  Then  came  a  remarkable  series  of  experiments  by  Bernstein,  in  which 
he  succeeded  in  detecting  and  measuring  the  velocity  of  the  wave  of  negative 
variation  in  a  muscle  or  nerve.  His  method  essentially  consisted  in  irritating  at 
regular  intervals  a  muscle  or  nerve,  and  in  observing,  during  these  intervals,  the 
effect  of  the  electrical  irritations  on  the  electromotive  properties  of  the  muscle  or 
nerve.  Mechanical  contrivances  were  invented  for  the  pvirpose  of  throwing  into 
the  circuit  of  a  galvanometer  (during  or  immediately  after  the  short  periods  of 
stimulation)  the  currents  from  the  muscle  or  nerve.  In  other  words,  suppose  a 
eurrent  flowed  along  a  muscle,  by  Bernstein's  arrangement  this  current  could  be 
tapped  or  drawn  off  into  the  galvanometer  circuit  at  different  points  of  itspio- 
gress.  This  was  accomplished  by  an  instrument  invented  by  Bernstein,  called  the 
differential  rlieotome,  a  form  of  which,  simpler  than  that  devised  by  Bernstein,  is 
shown  in  Fig.  301. 


This  instrument  serves  the  purpose  of  stimulating  an  organ,  say  a 
nerve  or  a  muscle,  "with  a  series  of  induction  shocks,  and  then,  at  short 
intervals  of  time  after  each  stimulation,  the  length  of  which  may  be 
varied  at  pleasure,  of  switching  the  organ  into  a  galvanometric  circuit. 


454 


Tilt:  CONTliACTlLE  TISSUES 


The   rhcotomc   lias   been  of  great  sci\ife  in    electro-physiology,  and 
merits  here  a  short  description. ^ 


Fig.  301. — Rheotome  of  Hermann.  From  a  photogvaph  of  the  instru- 
ment in  the  Physiological  Laboratory  at  Oxford.  For  tlescriijtiou 
see  text. 

The  wheel,  W,  makes  say  10  revolutions  per  second.  The  primary  circuit  of  the 
inductorium,  of  which  the  upper  pair  of  coiled  wires  form  jjart,  is  open,  excepting 
when,  as  happens  each  time  W  revolves,  the  needle  at  o'  strikes  the  wire  at  e,  the 
brush  being  at  the  same  time  in  contact  with  the  block.  The  other  two  coiled 
wires  are  those  of  the  galvanometric  circuit.  These  end  in  the  blocks  h  and  V ,  so- 
that  the  galvanometer  circuit  is  closed  only  when  both  brushes  are  in  contact  with 
them.  As  one  of  these  blocks  slides  on  the  other,  the  duration  of  the  contact  can 
be  varied.  In  using  the  instrument,  the  zero-position  of  the  disk  miist  be  lirst 
determined,  that  is,  the  position  in  which  it  must  be  placed  in  order  that  the 
galvanometer  circuit  may  be  closed  at  the  xavu  moment  that  the  needle  touches  the 
wire.  This  having  been  done,  the  shifting  of  th6  disk  by  one  division,  in  the- 
direction  of  the  hands  of  a  watch,  t/e/er.s  tlie  galvanometric  contact  by  one  hun- 
dredth of  a  revolution  period,  and  so  on.  It  will  be  understood  that  in  an 
observation  with  the  repeating  rheotome  the  successive  galvanometric  effects  sum 
together. 

Theories  of  the  Mmde  Chirrents. — These  may  be  Ijriefi}-  alluded  to  as- 
three  in  number. 

1.  The  Electro-capillari/  Theorij  of  Becquerel.^ — He  showed  that  electro- 
chemical circuits  may  exist,  as  in  the  body,  without  the  existence  of  a 

^  I  have  to  thank  Prof;  Burdon-Sanderson  for  aiding  mc;  witli  regard  to  this- 
instrument. 
-  Becquerel,  Cojupfe^:  Benda-^,  1870. 


THE  ELECTRICAL  PHENOMENA  OF  MUSCLE.  455 

metal.  Two  liquids  of  a  different  nature,  separated  by  a  narrow  slit  or 
series  of  pores,  or  by  an  organic  membrane,  may  give  rise  to  a  current ; 
the  wall  which  is  in  contact  with  the  liquid  next  the  acid  acts  as  the 
negative  pole,  while  the  opposite  wall  is  the  positive — the  walls  of  the 
capillary  spaces  acting  as  solid  conductors.  According  to  Becquerel, 
the  tissues  of  the  body  present  an  infinite  number  •  of  electro-capillary 
couples,  which  give  origin  incessantly  to  electric  currents.  Thus,  in 
the  capillaries  of  the  tissues,  the  face  of  the  capillary  wall  in  contact 
vnXh.  the  blood  is  the  negative  pole,  whilst  the  face  in  contact  with  the 
fluid  bathing  the  tissues  is  the  positive  pole.  This  theory  rests  on  an 
insufficient  basis  of  fact,  and  does  not  account  for  the  phenomena. 

2.  The  Physical  Theory  of  Du  Bois-Eeymond.'^ — If  we  take  a  cylinder 
of  zinc,  having  a  l)it  of  copper  soldered  on  each  side,  and  plunge  it  into 
water,  there  are  formed  an  infinite  number  of  isolated  currents,  which 
travel  through  the  water  from  the  zinc  to  the  copper,  and  a  part  of 
which  may  be  conveyed  by  conductors  applied  to  the  zinc  and  to  the 
copper.  If,  then,  a  galvanometer  be  interposed  in  the  circuit,  it  will  be 
found  that  the  zinc,  forming  the  centre  of  the  cylinder,  is  positive,  and 
the  copper,  forming  the  sides,  is  negative,  a  result  comparable  to  that 
obtained  from  a  muscle.  Du  Bois-Reymond  has  suggested  therefore  that 
each  muscular  fibre  is  composed  of  an  infinite  number  of  small  electro- 
motive elements,  analogous  to  the  cylinder  composed  of  zinc  and  copper 
above  described.  Each  little  element  would  have  a  positive  equatorial 
zone,  and  two  negative  polar  zones,  and  would  be  plunged  into  an 
intermediate  conducting  matter.  The  series  of  electromotive  elements 
in  a  muscle  might  be  represented  thus — 

or,  supposing  each  element  to  be  divided  into  two  dipolar  molecules, 
having  the  positive  poles  turned  in  the  same  direction,  thus — 

—  +  + +  + +-1- +  + +  +  — 

In  the  accompanying  figure  M  shows  a  dipolar,  and  L  a  tripolar 
arrangement  of  such  electromotive  molecules — the  darkly-shaded  por- 
tions of  the  circles  representing  the  negative  parts  (Fig.  302,  p.  456.) 

It  is  clearly  to  be  understood  that  those  electromotive  molecules,  or 
"carriers  of  electromotive  forces,"  do  not  exist  in  any  histological 
sense;  they  may  be  nothing  more  than  "the  foci  of  chemical  change." 

1  Du  Bois-Reymond,  Unttrsuchungen  iiber  Thierische  klectricitat,  1848  to  1860. 
See  also  a  translation  by  Mrs.  Lauder  Brunton  of  his  paper  "On  the  Secondary 
Electromotive  Phenomena  in  Muscles,  Nerves,  and  Electrical  Organs,"  in  Transla- 
tions of  Foreign  Biological  Memoirs,  1887,  edited  by  Professor  Burdon-Sanderson. 


456 


THE  CONTRACTILE  TISSUES. 


(Du  Bois-Reymond.)     The  existence  of  molecules  also  enters  into  the 
conception  of  the  i^hysicist  regarding  the  nature  of  electrolysis. 


P  M  N 

Fjg.  302. — Diagram  showing  the  hypothetical  molecules  of  Du  Bois-Reymond. 

Du  Bois-Reymond,  in  his  earlier  experiments,  thought  he  obtained  a 
current  from  an  uninjured  muscle — i.e.  from  one  whose  longitudinal 
and  transverse  sections  were  natural,  and  not  artificially  produced. 
Later,  hoM^ever,  he  discovered  that,  if  special  precautions  had  been 
taken  not  in  the  slightest  degree  to  injure  the  muscle,  no  stream  was 
obtained  in  the  resting  state,  though  on  the  production  of  tetanus  the 
usual  negative  variation  was  observed.  If  a  stream  were  obtained 
Avhen  the  muscle  was  at  rest  it  was  in  greatly  diminished  amount, 
and  might  even  be  in  a  direction  quite  contrary  to  the  usual.  Du  Bois- 
Reymond  explained  this  by  supposing  that,  in  the  uninjured  muscle, 
the  tendinous  end,  which  is  the  natural  transverse  surface,  contains  a 
layer  of  electromotive  molecules,  with  their  poles  reversed,  so  that 
their  positive  surface  is  towards  the  transverse  section.  This  layer  he 
called  the  parelectronomic  layer,  and  when  one  removes  it  by  making  an 
artificial  cross  section,  the  full  muscle  current  is  obtained. 

This  layer  Avith  reversed  poles  is  represented  in  the  figure  by  P, 
while  N  represents  the  arrangement  in  an  oblique  section,  giving  rise 
to  the  "  inclination  currents." 

3.  The  Contact  Theory  of  Hermann.^ — These  views  of  Du  Bois-Reymond 
have  found  an  ojDponent  in  Professor  L.  Hermann,  of  Ziirich,  who  con- 
cludes, from  many  carefully-made  observations,  that  in  the  absolutely 
uninjured  frog's  nmscle  there  is  no  current.  He  believes  that  the  cur- 
rent is  the  result  of  injury,  causing  death  of  a  small  part  of  the  muscu- 
lar fibre,  and  so  producing  difference  of  potential.  In  support  of  his 
views  he  adduces  many  arguments  and  observations.  There  are  few 
muscles  which  can  be  prepared  without  some  slight  injuxy,  since  in  the 
majority  of  cases  connective  tissue  fibres  pass  out  from  the  muscle 

•'L.  Hermann.  The  results  of  liis  numerous  investigations  are  summed  up 
in  Human  Phj/siolog;/,  translated  and  edited  by  Dr.  Arthur  Gamgee,  F.R.S. ,  etc., 
chap,  viii.,  and  the  most  recent  expression  of  his  views  is  contained  in  a  paper 
in  Burden-Sanderson's  Translations  {op.  cit.),  translated  by  Mr.  Francis  Gotch, 
entitled,  "  On  so-called  Secondary  Electromotive  Phenomena  in  Muscle  and  Nerve." 


THE  ELECTRICAL  PHENOMENA  OF  MUSCLE. 


457 


to  the  skin,  and  in  stripping  off  the  skin  the  fibres  are  torn,  and  an 
artificial  cross  section  produced.  Du  Bois-Eeymond,  therefore,  tried  to 
obtain  the  current  from  the  muscle  in  situ — i.e.  without  stripping  off 
the  skin — but  found  in  the  frog  strong  skin  currents  directed  from 
without  inwards,  which  interfered  with  the  experiment.  These  skin 
currents  are  abolished  by  corroding  the  skin,  e.g.  with  saturated  salt 
solution,  and,  when  this  has  been  done,  the  ordinary  muscle  stream  is 
obtained.  Hermann  objected  that  the  corrosive  agent  not  only  set 
aside  the  skin  current,  but  permeated  to  the  muscle  itself,  and  acted  on 
it,  producing  chemically  a  transverse  section,  so  that  the  current  ob- 
tained was  not  from  the  uninjured  but  from  the  injured  muscle.  In 
fishes,  which  exhibit  no  skin  current,  and  where,  therefore,  corrosion 
of  the  skin  is  unnecessary,  no  muscle  current  is  obtained  when  the  fish  is 
curarized  to  render  motion  impossible.  Hermann  also  points  to  the 
fact,  shown  by  Engelmann,  that  the  heart,  which  can  be  laid  bare  with- 
out injury  to  its  fibres,  shows  no  resting  current,  though  it  shows  a 
negative  variation.  Hermann  found  that  even  the  secretion  of  the 
skin  of  the  frog  applied  to  the  muscle  produced  by  its  action  a  current, 
indicating  injury  of  the  fibres.  Engelmann  also  showed  that  a  section 
jiroduced  sul)cutaneously  in  a  living  muscle  gave  rise  to  a  current, 
which,  however,  disappeared  on  the  repair  of  the  injury. 

From  such  facts  Hermann  concludes  that  striated  muscle  in  a  perfectly 
uninjured  conditian  is  absolutely  streamless,  and  that  the  muscle  stream  is 
connected  with  the  existence  of  an  artificial  transverse  section.     Ac- 
cording to  him,  a  muscular  fibre  exhibits  a 
current  only  when  one  part  of  it  is  dying 
and  the  other   part   is   still   living   proto- 
plasm, but,   as'  soon  as  the  whole  fibre  is 
dead,  the  stream  disappears.     In  order  to 
verify  this  view,  Hermann  devised  an  ap- 
paratus called  the  "  Fall  Rheotome." 

By  means  of  a  falling  weight,  F  (Fig. 
303),  shod  with  shagreen,  part  of  the 
aponeurosis  of  the  tendo  Achilles  of  a 
gastrocnemius,  M,  is  stripped  off,  and, 
almost  instantaneously  with  this,  the  galva- 
nometer circuit  is  closed,  and,  in  a  very 
short  time  thereafter,  opened  by  the  same 
weight(Fig.  304).  By  this  means,  and  through 
a  compensation  arrangement,  the  amount  of 
current  obtained  from  the  muscle  immed- 
iately  after   injury   is   measured.      A   second   similar   observation   is 


Pig.  303.— Fall-rheotome  of 
Hermann. 


458 


THE  CONTRACTILE  TISSUES. 


immediatelj'  made  on  the  same  muscle  now  injured.  Hermann  found 
that  there  Avas  a  deflection  of  the  needle  obtained  from  the  muscle 
immediately  on  its  injury,  but  the  second  observation  gave  a  very 
much  greater  deflection,  shoAving  that  after  the  injiuy  the  current  took 
a  little  time  to  develop.  This  time,  in  the  gastrocnemius  of  the  frog, 
Hermann  gives  as  -^^-^  of  a  second,  that  is  to  say  the  electrical  effect  is 
not  immediate,  but  takes  ^^  of  a  second  to  develop  after  injury. 
Hermann  admits  the  occurrence  of  negative  variation  in  the  injured 
muscle,  but,  since  he  denies  the  existence  of  a  stream  in  an  absolutely 
uninjured  resting  muscle,  he  cannot  admit  a  negative  variation  in  the 
uninjured  muscle.  Still,  on  stimulating  an  uninjured  muscle  Avhich 
exhibits  no  current,  a  deflection  of  the  needle  is  observed.  This  cur- 
rent, obtained  in  Cjuite  normal  muscle  by  stimulation,  Hermann  calls 
the  action  current,  which  passes  in  the  muscle  from  longitudinal  to 
transverse  surface.  The  time  of  occurrence  of  this  action  current  or 
negative  variation  has  been  fixed  by  Yon  Helmholtz  and  Von  Bezold  as 
preceding  the  contraction  of  the  muscle,  that  is  to  say,  during  the 
latent  period. 

By  means  of  the  rheotome  Bernstein  ob- 
tained by  stimulation  of  a  muscle,  which 
gave  no  current  while  at  rest,  not  only 
a  single  but  a  double  deflection  of  the 
needle,  the  first  in  the  negative,  the 
second  in  the  positive  direction.  This 
double  variation  was  found  to  propagate 
itself  through  the  muscle  at  the  same  rate 
as  the  wave  of  excitation.  The  "  negative 
variation '"'  then,  or  "  action  stream,"  is 
associated  with  the  passage  through  the 
muscle  of  a  wave  of  excitation.  During  the 
passage  of  the  Avave  each  irritated  muscle 
point  becomes  negative  to  a  point  at  rest, 
that  is,  when  the  wave  reaches  a  point 
it  becomes  negative  to  another  point 
beyond  the  Avave,  and  AA^hen  the  wave  has  passed  the  first  point 
it  returns  to  a  jjositiA'e  condition  in  relation  to  the  part  of  the  muscle  to 
which  the  Avave  has  noAV  passed.  The  one  point  being  first  negatiA'e  and 
then  positive  explains  the  double  deflection.  In  a  muscle  Avith  an  artificial 
cross  section,  the  second  phase  of  the  double  deflection  disappears,  and 
thus  the  negatiA'e  variation  is  accounted  for.  In  a  totally  tetanized 
muscle,  in  Avhich  the  stimuli  jjass  so  rapidly  that  the  irritation  AvaA^e  is 
everyAvhere  present,  no  "action  stream"  is  found. 


Fig.  304. — Diagram  showing  part 
(if  the  arran>;enieiit  of  the  "  Fall 
Rheotome."  The  falling  weight 
F  having  injured  the  muscle  in 
the  way  shown  in  Fig.  303,  is 
then  made  to  strike  against 
keys  a,  X,  O,  by  which  the 
galvanometer  circuit  can  be 
closed  and  then  opened,  or  other 
effects  produced  speedily,  the  one 
after  the  other. 


THE  ELECTRICAL  PHENOMENA   OF  MUSCLE.  459 

The  Current  in  a  Livimg  Man. — Such  is  a  general  statement  of  the 
facts  offered  by  Du  Bois-Eeymond  and  Hermann  for  and  against  the 
theory  of  an  electrical  current  in  normal  living  muscle.  If  Du  Bois- 
J?,eymond  were  correct  it  "vvas  natural  to  suppose  that  the  muscles  of  a 
living  man  would  show  a  considerable  current,  and  a  negative  variation 
on  voluntary  contraction.  But  Du  Bois-Reymond  completely  failed  to 
detect  a  current  from  the  living  muscles  of  man  at  rest.  If,  however,  one 
dips  both  hands  into  ^ailcanite  troughs  filled  with  salt  solution  and 
connected  with  the  galvanometer,  and  then  voluntarily  contracts  the 
muscles  of  one  arm,  the  needle  is  deflected  to  one  side  ;  if  the  muscles 
of  the  opposite  arm  are  contracted,  the  needle  swings  in  the  opposite 
direction.  This  Du  Bois-Reymond  accounted  a  negative  valuation. 
But  Hermann  declares  it  to  be  no  muscle  current  at  all,  but  to  be  due  to 
a  secretion  stream  directed  from  Avithout  inwards  on  the  irritated  side — 
a  skin  current.  In  his  experiments,  stimulation  produced  sweating  and 
the  electric  current,  but  when  atropia  Avas  given  both  disappeared. 
"  A  man,"  he  says,  "  paralyzed  by  curare  would  show  the  Du  Bois- 
'Reymond  current  in  spite  of  the  absence  of  contraction,  and  a  man 
under  the  influence  of  atropia  would  not  show  the  current  in  spite  of 
the  occurrence  of  contraction."  ^  That  is,  in  the  former  case,  stimula- 
tion could  not  produce  contraction  on  account  of  the  curare,  but  it 
would  produce  sweating,  and  a  current — a  secretion  stream — would 
appear ;  in  the  latter  case  it  would  produce  contraction,  but  on  account 
of  the  atropia  there  could  be  no  sweating  and  there  would  be,  therefore, 
no  current. 

To  the  Du  Bois-Reymond  theory  of  polar  particles,  or  the  pre- 
existence  theory,  Hermann,  therefore,  opposes  what  he  calls  a  difference 
theory  because  it  refers  all  electromotive  effects  of  muscle  to  two  kinds 
of  physiological  change.  The  first  part  of  the  theory  is  that  ihe  dying 
poiiion  of  the  substance  behaves  itself  negatively  to  the  living,  and  the  electro- 
motive force  has  its  seat  in  the  demarcation  zone  between  the  living  and 
the  dying.  To  this  he  adds  a  rider  that  not  only  death  but  irritation  as 
well  causes  the  affected  substance  to  become  negative  to  the  unaffected  portion. 

Hermann  enunciates  his  views  in  the  following  four  propositions — 

(1)  "Localized  death  in  continuity  of  protoplasm,  whether  caused  by  injury  or  by 
metamorphosis  (mucous,  horny),  renders  the  dead  part  negative  electrically  to  the 
unaltered  part ;  (2)  Localized  excitation  in  continuity  of  protoplasm  renders  the 
excited  part  negative  electrically  to  the  unaltered  part ;  (3)  Localized  waiming  in 
continuity  of  protoplasm  renders  the  warm  part  positive,  localized  cooling  the 
cold  part  negative  to  the  unaltered  part ;  (4)  protoplasm  is  strongly  polarizable 

^  Hermann,  Handbuch  der  Phys.,  Bd.  I.  Th.  I.  .s.  224  u.  225. 


4G0  THE  CONTRACTILE  TISSUES. 

on  its  limiting  surfaces  (first  shown  as  regards  the  protoplasm  enclosed  in  tubes 
of  muscles  and  nerves)  ;  the  polarization  constant  decreases  on  excitation  and  on 
dying."  ^ 


Chap.  XIX.  -SUMMARY  OF  THE  PHENOMENA  OF  A  LIVING 

MUSCLE. 

When  the  energy  which,  for  want  of  a  l)etter  term,  is  called  nerve 
force  reaches  a  muscle  fibre,  it  acts  on  the  motor  end-plate,  probably 
setting  up  molecular  changes  in  it  which  are  propagated  to  the  con- 
tractile substance  of  the  muscle.  These  molecular  changes  raj^idly  pass 
towards  each  end  of  the  fibre  and  they  occur  simu.ltaneously  with,  and 
are  the  source  of,  the  action  current  or  negative  variation.  According 
to  Du  Bois-Reymond,  this  wave  of  negative  variation  is  due  to  the 
polarization  of  hypothetical  electromotive  molecules,  while  the  rival 
theor}'  of  Hermann  assumes  that  the  result  of  the  nerve  stimulation  is 
to  produce  negativity  at  the  point  stimulated,  and  that  this  negativity 
(as  regards  other  points)  passes  from  point  to  point  along  the  muscle, 
thus  producing  a  current,  but  it  is  important  to  notice  that  the  fad  of 
the  propagation  of  a  wave  of  electrical  disturbance  has  been  established 
and  is  independent  of  the  theories  offered  as  to  its  explanation.  The  short 
period  during  which  the  action  current  passes  through  the  fibre  does  not 
exceed  the  y^^-  of  a  second,  and  for  the  longer  period  of  the  yi-„  of 
a  second  the  fibre  is  apparently  inactive.  This  is  the  period  of  latent 
stimulation,  and  during  this  period  molecular  phenomena  are  occurring 
which  are  antecedent  to  contraction.  It  is  highly  probable  also  that 
during  the  period  of  latent  stimiilation  energy  is  liberated  as  heat,  but 
ii  portion  of  the  heat  of  muscular  tissue  is  probably  evolved  during  the 
succeeding  phase  of  active  contraction.  At  the  end  of  the  latent  period, 
the  fibre  contracts,  and  during  the  contraction  of  a  number  of  fibres 
existing  together  in  the  organ  we  term  a  muscle,  a  sound  is  produced — 
the  muscle  sound.  The  muscle  fibre  then  relaxes  and  the  katabolic 
products  of  the  nervous  stimulus  are  then  quickly  removed  and  the  muscle 
substance  is  built  up  anew.  Another  consequence  of  the  molecular  dis- 
turbance excited  by  the  nervous  stimulus  is  the  increased  production 
of  carbonic  acid  and  probably  of  other  waste  products  and  the  increased 
consumption  of  oxygen.  This  resum^  embraces  the  principal  phenomena, 
but  others  have  been  mentioned  in  the  preceding  pages.  The  student 
should  make  himself  master  of  the  physiological  changes  in  muscle  as 
they  illustrate  in  a  striking  way  the  anabolic  and  katabolic  processes 
occurring  in  living  matter,  and  he  will  see  that  many  of  the  processes 
^  Burdon-Sanderson's  Translations,  op.  cit.  p.  328. 


TEE  PHENOMENA  OF  THE  ELECTRIC  FISHES.  461 

happening  in  other  tissues,  such  as  in  glands,  in  the  sense  organs,  and 
even  in  the  central  nervous  organs  are  analogous  to  those  of  muscular 
contraction. 

Chap.  XX.— THE  PHEISrOMENA  OF  THE  ELECTEIC  FISHES. 

The  phenomena  manifested  by  electrical  fishes  have  in  recent  years 
attracted  the  attention  of  various  phj^siologists  as  bearing  on  the  mode 
of  action  of  muscles,  and  especially  of  nerves.  The  indefatigable 
labours  of  Sachs,  Fritsch,  Ranvier,  and  many  others,  by  which  they 
have  been  able  to  describe  the  histological  structure  of  electric  organs, 
and  the  elaborate  researches  of  Du  Bois-Reymond  and  of  Sachs,  and  more 
recently,  in  this  countr}',  of  Burdon-Sanderson  and  Gotch,  on  the 
electrical  phenomena  manifested  by  these  organs,  have  brought  to 
light  many  details  of  one  of  the  most  remarkable  structiu'es  in  the 
whole  realm  of  nature.  To  do  justice  to  this  subject  would  lead  me 
beyond  the  space  at  my  disposal,  but  I  will  attempt  to  give  a  brief 
account  of  the  chief  facts,  because  a  general  knowledge  of  these 
cannot  fail  in  being  both  interesting  and  suggestive  to  the  physiological 
student. 

About  fifty  species  of  fishes  are  known  or  are  believed  to  possess. 
electrical  organs,  and  to  have  the  power  of  communicating  electrical 
shocks.  This  may  possibly  be  an  over  estimate  of  the  number,  and  at 
all  events,  the  electrical  properties  "of  not  more  than  five  or  six  have 
been  investigated.  From  one  point  of  view,  it  is  remarkable  that 
any  animal  should  possess  an  electrical  apparatus,  but  yet  when  one 
considers  the  value  of  such  an  organ  to  the  animal,  as  a  weapon  of 
offence  or  of  defence,  it  may  appear  strange  that  an  electrical  organ  has 
been  found  only  in  a  few  fishes. 

The  electrical  fishes  best  known  are  Torioedo  Galvani,  or  T.  marmorata, 
and  some  other  species  of  torpedo  found  in  the  Adriatic  and  Mediterranean 
seas ;  Gymnotiis  eledricus,  an  eel  living  in  the  lagoons  in  the  region  of 
the  Orinoco  in  South  America ;  and  Malapterurus  eledricus,  the  ra"  ash, 
or  thunderer  fish  of  the  Arabs,  a  native  of  the  Xile,  the  Xiger,  the 
Senegal,  and  other  African  rivers.  In  addition  to  these,  we  know  of 
Mwmyrus  longipinnis,  M.  doi'salis,  and  M.  anguilloides,  fishes  allied  to  the 
jjike  family,  found  in  the  Nile  ;  Rhinobatus  eledricus,  a  ray  from  Brazilian 
seas ;  and  Tridiiurus  eledricus,  a  ribbon-like  fish  found  in  the  Indian 
Ocean.  The  common  skate  of  our  own  coasts,  Fucia  batis,  also  possesses, 
an  electrical  organ,  first  described  by  Stark  in  1844,  afterwards,  in 
1847,  by  Robin,  and  the  electrical  properties  of  which  have  been 
recently  investigated  by  Burdon-Sanderson  and  Gotch.      It    will    be 


462 


THE  CONTRACTILE  TISSUES. 


observed  that  the  electrical  fishes  do  not  liclont;-  to  one  class  or 
group,  and  that  some  are  found  in  fresh  water,  while  others  inhabit 
the  ocean. 

Electrical  fishes  have  been  known  from  early  times.  Aristotle 
describes  the  benumliing  shocks  of  the  torpedo,  as  recognized  by  fisher- 
men ;  and,  in  a  recent  work  on  the  malapterurus,  Fritsch  figures 
an  ancient  Egyptian  carving,  executed  3,000  years  before  the  Christian 
era,  in  which  fishes,  like  malapteruri,  are  distinctly  seen.  It  was  not 
until  1773,  however,  that  Walsh  showed  experimentally  that  the  shocks 
of  the  toi'pedo  are  electrical  in  their  nature.  Since  that  period,  many 
investigations  have  been  made,  both  as  to  the  structure  and  as  to  the 
functions  of  the  electric  organs. 

1.  Torpedo. — The  electric  organs,  two  in  number,  are  large,  flat, 
kidney-shaped  bodies,  placed  on  each  side  of  the  head  and  gills.  The 
organ  is  composed  of  a  number  of  hexagonal  prisms,  placed  vertically 
Jietween  the  dorsal  and  abdominal  integuments,   and   each   prism   is 

divided  by  a  series  of  delicate 
membranous  plates  or  diaphragms 
nttached  by  their  edges  to  the 
aponeurotic  sheaths  separating  the 
})risms  (Fig.  305).  The  plates  are 
separated  from  each  other  by  a  jelly- 
like albuminous  fluid.  About  30 
plates  occur  in  each  mm.,  linear 
measurement,  of  a  prism,  and  a,  i)rism 
of  medium  height  contains  about 
615  jjlates.  Each  organ  contains 
say  800  prisms,  and  thus  there  are 
roughly  about  500,000  plates  in 
each  organ,  or  1,000,000  in  both 
organs.  This  powerful  electric  bat- 
tery, thus  divided  into  compartments 
is  richly  supplied  with  large  nerves. 
These  are  (1)  a  large  branch  from 
the  trigeminal,  and  (2)  four  branches 
from  the  vagus  which  spring  from 
a  large  lobus  dectricus  between  the 
corpora  higeniina  and  the  medulla 
■ohlongata.  According  to  Pacini,  the  nerves  enter  the  laminte  at  the 
points  of  their  attachment  to  the  prisms,  and  are  disti'iljuted  to  their 
under  surface,  and  in  the  fluid  between  that  surface  and  the  next 
lamina       They  ramify  here  in  a  very  vascular  nucleated  tissue.     Each 


Via.  305. — Torpedo  Galvani,  showing  the 
prisms  fi-oni  the  dorsal  surface,  and  the 
gi-eat  nerve  trunks,  b,  ending  in  the  smaller 
nerves  a,  distributed  to  the  prisms. 


THE  PHENOMENA  OF  THE  ELECTRIC  FISHES. 


463 


prism  presents  a  structure  somewhat  analogous  to  that  of  a  voltaic  pile. 
The  piles  are  vertical  and  the  plates  horizontal.  Savi,  in  1844,  observed 
that  the  nerves  ended  in  the  electric  plates  in  the  form  of  a  rosette. 

According  to  Ewalcl,  one  of  the  most  recent  writers  on  the  subject,  the 
electric  nerves  pass  through  the  gills  and  enter  the  electric  organ  as 
four  large  branches  and  one  smaller  branch.  They  then  divide  freely, 
and  run  between  the  prismatic  columns,  always  ending  near  the 
middle  of  the  column.  From  these  smaller  branches  still  smaller 
ones  originate,  each  consisting  of  three  or  four  fibres,  and  these 
spread  out  obliquely  over  the  lateral  siu-face  of  the  column.  Each 
nerve  fibre  divides  into  from  12  to  25  delicate  nerve  filaments, 
called  by  "Wagner,  their  discoverer  (1847),  nerve  tufts  (nervenbiischel) 
(Fig.  306).  Each  nerve  tuft  gives  off  as  many  fibrils  as  there 
are  plates  in  the  column,  each  jDlate  being  supplied  Avith  one   fibril. 


Fig.  306. — Xerve  tuft  in  tor- 
pedo, showing  numerous 
little  branches  coming  off 
from  the  larger  nerve. 


Fig.  307. — Terminations  of  nerve  on  the  plate  of 
the  prism  of  a  torpedo,  seen  after  the  action  of 
osmio  acid,     x  800  d. 


Fig.  308.— Diagram  of  prism  of 
torpedo,  showing  11  plates, 
each  supplied  by  its  nerve 
fibre,  issuing  from  the  chief 
nerve  A,  so  as  to  form  one  of 
Wagner's  tufts. 


The  main  nerve  reaches  the  centre  of  the  column,  and  the  branches 
given  off  from  it  to  the  individual  plates  lie  almost  in  a  straight  line  or 
plane  parallel  to  the  axis  of  the  column.  These  fibrils  do  not  pass  to 
the  plates  by  the  shortest  course,  but  only  the  shortest  fibres  go  directly 


464 


THE  CONTRACTILE  TISSUES. 


to  the  plates,  the  majority  making  a  hook-shaped  bend,  and  then  each 
reaches  its  appropriate  plate  after  a  course  of  greater  or  less  length. 
This  arrangement  is  seen  in  Fig.  308.  When  a  fibril  reaches  a  plate,  it 
divides  dichotomously  again  and  again  so  as  to  form  an  expansion,  as 
seen  in  Fig.  307,  and  it  is  remarkable  that  the  arrangement  of  the 
divisions  of  the  fibril  on  one  plate  corresponds  almost  exactly  Avith  that 
on  neighbouring  plates.  The  final  little  twigs  of  nerve  end  by  forming 
an  anastomosis  with  adjoining  fibrils,  and  thus  produce  what  may  be 
called  an  electrical  end-plate.  The  fact  that  a  single  nerve  fibre,  by 
splitting  into  fibrils  supplies  from  1 2  to  25  plates,  shows  that  all  those 
plates  may  be  thrown  into  electrical  activity  at  the  same  time  by  one 
nervous  impulse. 

Eanvier  describes  the  structures  between  each  pair  of  plates  of  the 
torpedo  as  consisting  from  below  upwards  of  (1)  a  first  layer,  or  nervous 
layer,  formed  of  two  portions — (a)  a  superficial  portion  containing  the 
plexus  of  nerve  fibrils  above  described,  and  {b)  a  deeper  layer  showing 

peculiar  finger-shaped  projections 
called  electric  hairs  by  Ranvier,  and 
lying  side  by  side  so  as  to  give  the 
appearance  of  a  palisade  (Remak) ; 
(2)  a  second,  or  intermediate  layer, 
also  consisting  of  two  parts — (a)  a 
superficial  or  ventral  portion,  finely 
granular,  next  the  palisade  of  elec- 
tric hairs,  and  (Ij)  a  deeper  portion, 
more  coarsely  granular  than  a,  and 
containing  nuclei ;  (3)  a  thin  clear 
layer,  called  by  Eanvier 
lamella ;  and 
tive  tissue, 
Above  this, 
or  nervous 
and  so  on. 
in  Fig.  309 


the    dmsal 

of  connec- 

partition. 


(4)   a   layer 

,  forming  a 
we  again  find  the  first 
layer  above  described, 
These   layers  are  shoAvn 

according  to  Eanvier. 


This  remarkable  organ  is  now  known 
to  be  related  to  muscular  tissue. 
Fritsch,  by  studying  the  development 
of  the  torpedo  at  Naples  and  Villa- 
franca,  has  found  that,  as  previously 
shown  by  De  Sanctis,  the  torpedo, 
in  its  ontological  history,  passes  through  a  squaliform  stage,  a  rajform 
stage  and  a  torpedo  stage ;  in  the  first  resembling  shark-embryos  in 


Fig.  309. — Attachment  of  the  electric 
plates  of  torpedo  to  the  sheath  of  the 
prism,  c/,  sheath  of  jsrism  ;  v,  ventral 
or  nervous  plate  ;  </,  dorsal  plate  ;  e, 
fine  layer  of  connective  tissue  ;  h,  in- 
termediate layer  ;  n,  nuclei  of  this 
layer ;  a,  a  portion  reflected  from  the 
plate. 


THE  PHENOMENA  OF  THE  ELECTRIC  FISHES.  4G5 

the  second  the  common  ray  or  skate,  and  in  the  third,  by  the  for- 
mation of  the  electric  organ,  it  becomes  a  true  torpedo.  At  an  early 
stage,  the  tissue  of  the  electric  organ  is  like  that  of  embryonic 
muscle,  showing  numerous  nuclei,  and  even  a  distinct  longitudinal  and 
a  more  faint  transverse  striation  may  be  seen.  Somewhat  later,  the 
striations,  both  longitudinal  and  transverse,  disappear,  the  nuclei 
become  larger  and  more  numerous,  and  the  disc-like  arrangement  of 
plates  begins  to  appear.  The  process  goes  on  until  the  slight  resem- 
blance to  muscle  is  entirely  lost.  There  can  be  no  doubt  that  the 
electric  organ  takes  the  place  of  the  outer  gill  muscles  of  the  fifth  gill 
arch.  These  muscles  in  ordinary  rays  and  in  sharks  constitute  powerful 
organs  for  moving  the  lower  jaw ;  but  in  the  torpedo  these  jaw  muscles 
are  absent,  and  in  their  place  we  find  the  electric  organ. 

In  the  electric  lobe  of  torpedo,  numerous  large  round  ganglionic  nerve 
cells  exist,  similar  in  appearance  to  those  described  and  figured  in 
treating  of  the  nerve  centres  of  Gymnotus  (p.  468). 

2.  Gymnotus  electricus. — This  fish  possesses  four  electric  organs,  two 
on  each  side,  stretching  from  the  pectoral  fins  to  near  the  end  of  the 
tail.  The  proportional  size  of  the  electric  organs  to  the  body  is  much 
greater  in  the  gymnotus  than  in  the  torpedo,  the  viscera  of  the  animal 
occupying  only  a  small  portion  of  the  anterior  part  of  the  body.  Each 
electric  organ  consists  of  a  series  of  horizontal  membranes  or  plates 
arranged  in  the  longitudinal  axis  of  the  body  nearly  parallel  to  each 
other.  Each  trough  is  divided  by  thin  vertical  laminte  or  diaphragms. 
According  to  Pacini,  each  lamina  is  not  simple  as  in  the  torpedo,  but 
it  may  be  regarded  as  consisting  of  two  layers  separated  by  a  fluid. 
The  posterior  layer  is  a  delicate  fibrous  structure,  and  in  it  alone  the 
nerves  ramify.  The  anterior  is  composed  of  vascular  nucleated  tissue. 
The  fluid  between  the  two  layers  of  the  laminse  diff'ers  in  character 
from  that  in  the  interspace  iDetween  the  posterior  and  the  anterior  layer 
of  the  next  lamina,  but  both  fluids  are  of  an  albuminous  character.  In 
the  gymnotus,  the  batteries  are  horizontal  and  the  plates  vertical — an 
opposite  arrangement  to  that  described  in  the  torpedo. 

A  more  careful  examination  than  was  possible  to  Pacini  has  enabled 
Fritsch  to  give  a  more  detailed  and  accurate  description.  According  to 
Fritsch,  the  electric  organ  consists  of  a  series  of  partitions  of  connective 
tissue,  between  which  lie  the  electric  plates.  These  contain  a  peculiar 
yellowish  albuminoid  material.  The  anterior  surface  of  the  plate  is 
covered  with  a  number  of  elongated  papillge  (anterior  papillse),  having 
rounded  ends  (Fig.  310),  and  in  these  papillae  there  may  be  seen 
granular  amoeboid  cells.  Between  the  papillse  and  the  anterior  parti- 
tion of  connective  tissue  there  is  a  transparent  mucoid  fluid,  in 
I.  2g 


4G6 


TtlE  CONTHACriLE  TISSUE>\ 


rfT^"-'       cC^^ 


Fig  310. — Yei'tical  section  through  one  of  the 
plates  of  the  electric  organ  of  gymnotus,  about 
l.SOO  diameters  (?) ;  serui-diagrammatic,  to  show 
all  the  structures.  P,  Pacini's  line  ;  'p,  anterior 
papillse ;  p',  posterior  papillae ;  st,  bacillary  layer ; 
p",  thorn  i^apilla ;  6,  amoeboid  cells  in  thorn 
papilla ;  observe  the  nerve  fibre  entering  the 
apex  of  this  papilla,  a,  nuclei  of  connective 
tissue  ;  el,  peripherical  electrical  nerve  ;  c,  c, 
nuclei  of  nei-ve  fibres  ;  d,  blood  corpuscles  in 
A'essel  ;  V,  posterior  surface  of  lamella  ;  tm, 
mucous  tissue  between  the  anterior  papUlaj  and 
the  next  lamella ;  s',  aponeurosis  between  the 
plates;  v  blood-vessel. 


which  a  few  cells  like  those  of 
connective  tissue  are  interspersed. 
The  middle  of  the  plate  is  trans- 
parent and  homogeneous  in  a 
fresh  condition,  but  soon  after 
removal  from  the  body  there 
appears  a  thin  dark  line,  called 
FacinVs  line,  dividing  the  plate 
into  two  parts.  The  posterior 
surface  of  the  plate  is  also  thrown 
into  papillse  (posterior  pajnlke)  of 
Aery  various  sizes,  constituting 
the  hacillary  layer,  some  being 
merely  short  rounded  projections, 
Avhile  others  called  tJm-n  papilla.'' 
are  long,  conical  in  shape,  and 
reach  nearly  to  the  posterior 
partition  of  connective  tissue. 
These  have  been  supposed  to  be 
supporting  pillars,  but  they  are 
regarded  by  Fritsch  as  really 
parts  of  the  electric  plate,  in  which 
the  electric  nerves  terminate. 
This  "vdew  is  clearly  borne  out 
by  Fig.  310  copied  from  one  of 
Fritsch's  drawings. 

The  ultimate  nerve  fibrils  pass 
along  the  anterior  surface  of  the 
partitions  and  shortly  before  en- 
tering the  papillae,  and  on  the 
posterior  surface  of  the  electric 
plate,  they  lose  the  white  sub- 
stance of  Schwann  (medullary 
sheath),  the  axis  cylinder  alone 
entering  the  electric  plates  and 
mersfino;  into  their  substance. 
The  medullary  sheath  breaks  up 
into  fibres  containing  nuclei  here 
and  there,  analogous  to  the  nuclei 
of  Eanvier's  nodes  in  a  nerve-fibre. 
These  small  fibrils  pass  to  the  pos- 
terior surface  of  the  electric  plate. 


THE  PHENOMENA  OF  TEE  ELECTRIC  FISHES. 


467 


The  microscopical  examination  of  the  electric  organ  of  the  gymnotus 
leads  to  the  conclusion  that  the  plates  arise  from  embryonic  muscle, 
each  plate  being  equivalent  to  a  number  of  primitive  bundles  cemented 
together.  In  some  preparations,  the  plates  may  be  found  broken  into 
parts  corresponding  to  the  individual  bundles,  or  rather  to  the  primitive 
•cylinders  or  fibres  of  eml^ryonic  muscle,  a  longitudinal  cleavage  taking- 
place  like  what  may  be  seen  in  muscle.  Sometimes,  again,  the  plates 
•cleave  transversely,  along  Pacini's  line,  a  division  analogous  to  that  of 
muscle  into  Bowman's  discs  (p.  309). 

While  the  nerve  cells  in  the  central  nervous  system  of  the  torpedo 
are  located  in  one  organ,  the  electric  lobe,  those  of  the  gymnotus  occur 
throughout  the  greater  part  of  the  length  of  the  spinal  cord.  This 
organ  in  the  gymnotus  is  not  specially  large,  „^ 
and  it  is  of  the  usual  shape.  In  the  anterior 
l^art  of  the  body  of  the  fish  it  is  somewhat 
flattened,  it  is  rounder  about  the  middle  of 
the  body,  and  is  again  flattened  towards  the 
tail.  No  special  cells  connected  with  the 
electric  nerves  occur  in  the  encephalon.  In 
the  spinal  cord,  however,  special  strands  or 
columns  exist,  one  in  each  lateral  half  of 
the  cord.  These  ganglion  cells  are  so  situated 
in  the  grey  matter  of  the  cord  as  to  surround 
the  central  canal  like  a  cylinder,  open  in- 
feriorly,  supposing  the  cord  to  be  placed  in 
the  natural  position  of  the  fish,  with  the 
back  upwards  and  the  belly  downwards. 
The  cells  are  seen  in  Fig.  311,  which  repre- 


Cuo 


J  a 


S.T. 

Fig.  31 1.— Kight  half  of  spinal  cord 
of  a  small  gymnotus,  seen  in  trans- 
ients one  half  of  a  transverse  section  of  the  "^^^^^  section,  x  30  d.  sr,  substantia 

reticularis  anterior  ;  sr' ,  substantia 

•cord.       Broad    axis    cylinders    arise    from    the  reticularis  lateralis ;  sr",  substantia 

11              1                            •  reticularis  posterior ; /a,  fasciculus 

poles    01    these    cells    and    run    out    into     the  anterior ;    cmt,  commlssura  trans- 

.  versa  ;  ne,  a  fe'w  small  nerve  cells  ; 

anterior  roots    01    the    spinal  nerves,  and  pass  '''<-'-e,  anterior  root  of  spinal  nerve; 

•■           ,           .                                 ,           .  >'<i.i),  posterior  root ; /i,  fasciculus 

on    to    tne    electric    organ    as    electric    nerves,  lateralis;  Cnc,  Central  canal  of  cord. 

rpi               J.        i>  J.1              1      i    •                                     1  Observe  the  large  ganglionic  cells 

ine  roots  01  these  electric  nerves   run  along-  in  the  grey  matter,  of  which  one  is 

side  the  ordinary  motor  roots  as  far  as  the  ^  "^"^  ^"^   '^' 

intervertebral  foramina.     The  remaining  poles  of  the  ganglion  cell ■ 

some  of  them  larger  than  others — run  into  the  neuroglia,  and  disappear 
in  the  direction  of  the  lateral  columns  and  of  the  commissure. 

The  electric  nerve-cells  are  of  a  roundish  form  (Fig.  312),  and  they 
consist  of  highly-granular  protoplasm,  from  which  very  distinct  poles 
{axis  cylinders)  emerge.  The  ordinary  multipolar  motor  cells,  charac- 
teristic of  the  spinal  cord  (Fig.  173,  p.  313),  become  the  fewer  the  more 


468 


THE  COS  TRACT  HE  TISSUES. 


numerous  the  electric  cells,  and  the  motor  cells  lie  exclusively  in  the 
anterior  coruua  or  horns  of  grey  matter.  The  shape  of  these  motor 
cclls  is  irregularly  ])olygonal,  often  Avith  concave  borders ;  there  is  less 
protoplasm,  and  the  poles  are  not  so  distinct  nor 
so  broad  as  is  the  case  with  the  electric  cells. 
According  to  Fritsch,  cells  transitional  from  the 
motor  to  the  electric  cells  may  be  observed.  The 
more  rounded  the  cell,  the  more  granular  the  pro- 
toplasm, and  the  more  distinct  the  poles,  the  more 
does  the  cell  become  of  the  electric  and  the  less  of 
the  motor  type.  Such  transitional  cells  occur  in 
the  inner  group  of  the  motor  cells  in  the  anterior 
cornua,  and  they  are  more  especially  present  in  a 
mass  of  grey  matter  in  the  cervical  region,  which, 
from  its  position,  is  analogous  to  the  vesicular 
column  of  Lockhart  Clarke,  seen  in  the  spinal 
cords  of  the  highest  vertebrates.  The  cells  in  this- 
grey  mass  are  few  in  number  and  small  in  size,, 
but  they  show  the  characters  of  electric  cells,  and 
they  send  their  poles  into  axis  cylinders,  passing- 
out  of  the  cord  by  the  anterior  roots.  Towards  the 
posterior  end  of  the  cord  the  electric  cells  become 
fewer  in  number,  and  gradually  their  characters  merge  into  those  of 
motor  cells. 

3.  Malapterums  eledricus. — The  electric  organ  in  this  fish  forms  a  layer 
beneath  the  skin,  enveloping  the  whole  body,  Avith  the  exception  of  the- 
head  and  fins.  A  layer  of  fat  separates  it  from  the  subjacent  muscles. 
The  ultimate  structure  shows  numerous  lozenge-shaped  spaces  or  loculi 
filled  with  fluid,  having  a  peculiar  layer  of  electric  tissue  on  two  sides 
of  the  lozenge-shaped  space,  as  shown  in  Fig.  313.  The  electric  tissue- 
consists  of  a  layer  of  granular  protoplasm,  containing  niiclei  (often 
double),  more  especially  towards  each  margin.  Both  borders,  and  more 
especially  the  inner  border,  show  a  delicate  striation,  which  really  con- 
sists of  tubular  pores,  represented  in  the  diagram.  Around  each 
nucleus  there  is  a  halo  of  clearer  protoplasm.  The  broad  firm  tubulated 
zone  is  distinct  from  the  more  slimy  inner  one.  Each  space  is  sur- 
rounded by  a  well  marked  fibrous  memljrane.  From  the  general  ap- 
pearance of  the  electric  tissue,  Fritsch  regards  it  as  consisting  of  a  layer 
of  modified  epithelial  cells  forming  giant  cells.  The  inner  free  surface 
is  bathed  in  a  mucoid  fluid.  In  the  epidermis  there  are  peculiar  club- 
shaped  cells,  having  double  nuclei  of  a  glandular  character,  which  are 
forms  transitional  into  those  constitutins;  true  electric  cells.     In  some= 


-Electric 
fi'om  the  middle  region  of 
the  spinal  cord  of  gymno- 
tus,  X  314  d.  a,  sheath 
of  neuroglia  ;  b,  smaller 
nerve  poles  anastomizing 
with  those  of  adjoining 
cells ;  c,  chief  nerve  pole, 
passing  into  axis  cylinder 
of  an  electric  nerve. 


THE  PHENOMENA  OF  THE  ELECTRIC  FISHES. 


409 


parts  of  the  body,  as  towards  the  tail,  the  lozenge-shaped  spaces  may 
be  found  without  any  electric  tissue,  and  transitional  conditions  also 
•occur.  Although  quite  different 
in  character  from  the  plates  or 
■discs  in  the  torpedo  and  the 
malapterurus,  being  epithelial 
instead  of  muscular,  the  lozenge- 
:shaped  arrangements  may  also  be 
■called  electric  discs.  The  num- 
ber of  these  discs  is  enormous. 
One  cubic  centimetre  of  the  elec- 
tric organ  of  a  middle-sized 
malapterurus  contains  14,000 ;  a 
transverse  section  through  the 
thickest  part  of  the  body  exposes 
-3,000,  in  a  row  from  head  to  tail 
1,600  are  found,  and  Fritsch 
•computes  that  the  total  number 
in  one  fish  amounts  to  2,000,000. 
On  tracing  the  nerve  into  the 
electric  organ,  it  is  found  that 
■only  the  axis  cylinder  enters  at 
•one  side  or  angle  of  the  space, 
and  that  it  insensibly  merges 
into  the  substance  of  the  electric 
tissue.  (See  Fig.  313,  n.)  The 
finest  nerve  fibrils  running  be- 
tween the  discs  have  an  ex- 
tremely thin  axis  cylinder  sur- 
rounded by  a  delicate  medullary 
.sheath  (white  substance),  and 
they  show  the  nodes  of  Eanvier. 
In  larger  nerves  no  longitudinal 
fibrillation  of  the  axis  cylinder  can  be  seen  under  the  action  of  osmic 
a,cid,  and  the  apparent  thickness  of  the  nerve  is  due  to  the  thick- 
ness of  the  medullary  sheath.  Xot  only  is  the  medullary  substance 
thicker,  but  the  nerve  fibril  is  surrounded  by  concentric  layers  of 
connective  tissue,  between  Avhich  even  delicate  capillaries  and  nerve 
fibrils  may  run.  When  the  nerves  are  traced  inwards  to  the  spinal 
cord,  they  are  all  found  to  spring  from  one  single  nerve,  the  electric 
nerve,  the  axis  cylinder  of  which  enters  the  cord  and  ends  in  a  process 
or  pole  of  a  gigantic  nerve  cell.     This  nerve  cell  has  numerous  proto- 


w  "  -,  ^ 

M    2    >    O 

^   «   ^   ^ 


470 


THE  COS  TRACTILE  TIS,^UES. 


I)lasmic  processes  which  coalesce  here  and  there  so  as  to  form  a  per- 
forated plate,  in  the  meshes  of  which  capillaries  and  nerve  fibres  may 
l)e  seen.  A  ganglionic  cell  of  similar  size  and  appearance  lies  in  the 
adjacent  half  of  the  spinal  cord,  and  both  cells  arc  connected  by  a 
commissure  passing  across  the  median  line.  Each  of  these  giant  nerve 
cells  measures  -21  mm.,  and  we  have  here  a  unique  example  of  an  organ 
being  supplied  by  one  nerve  cell. 

The  axis  cylinder  springing  from  one  of  the  poles  of  the  perforated 
nervous  plate  is  only  moderately  thick,  but  as  it  ultimately  supplies  a 
nerve  fibril  to  each  electric  disc,  the  sum  of  the  transverse  sections  of 
these  idtimate  fibrils  must  greatly  exceed  that  of  the  parent  nerve.  If 
we  call  the  transverse  section  of  the  parent  nerve  1,  the  total  trans- 
verse section  of  the  chief  larger  branches  Avill  be  represented  by  2,  and 
the  increase  goes  on  so  rapidly  that  the  sum  of  the  transverse  sections- 
of  the  ultimate  fibrils  reaches  the  enormous  amount  of  364,000,  showing 
the  remarkable  fact  of  a  gradual  increase  in  the  amount  of  matter  form- 
ino-  the  axis  cylinder  as  we  pass  from  the  spinal  nerve  cell  to  the 
ultimate  nerve  fibril.  It  would  appear  that  a  similar  increase  is  seen  in 
the  nerves  of  other  animals,  a  fact  not  yet  sufficiently  recognized  in 
theories  of  nervous  conduction.     (See  p.  316.) 

The  malapterurus  has  a  complete  lateral  nervous  system,  similar  tO' 
that  of  silurus,  and  Fritsch  states  that  the  electric  nerve  is  a  portion 
of  this  system  Avhich,  though  originating  from  the  trigeminus  nerve,. 
is  in  other  and  non-electric  malapteruri  connected  with  the  vagus. 

The  fresh  electric  organ  of  malapterun^s  was  found  by  Du  Bois- 
Reymond  to  have  a  neutral  reaction.  It  became  acid  on  the  third  day 
after  death.  After  immersion  for  five  minutes  in 
Avater  at  40°  to  50°  C.  it  gave  an  acid  reaction. 
Thrown  into  boiling  water,  pieces  of  electrical  organ 
became  acid,  thus  behaving  like  the  tissue  of  the 
central  nervous  organs,  and  not  like  muscle. 

4.  Baia  hutis,  or  Common  Skate. — Professor 
Burdon-Sanderson  and  Francis  Gotch  have  recently 
investigated  the  structure  and  functions  of  the 
electrical  organ  in  the  skate,  and  have  supplied 
me  with  the  following  short  sketch — ■"  On  each 
side  of  the  spinal  column  from  the  caudal  fin  to- 
about  half  way  up  the  tail  of  this  fish,  partly  in 
contact  ^^dth  the  skin,  and  partly  enveloped  in  the 
so-called  sacro-lumbalis  muscle  (Goodsir)  there  is  an  elongated  fusiform 
body,  consisting  of  a  number  of  longitudinal  series  of  discs  (Fig.  314).  It 
is  divided  by  septa  of  connective  tissue  into  tubes,  in  which  the  discs  are 


Fig.  314.— Diagram 
showing  the  geiieml 
arrangement  in  the 
skate  (liaia)  of  the 
discs  and  iinmcular 
fibres  as  seen  in  a 
longitudinal  section. 


THE  PHENOMENA  OF  THE  ELECTRIC  FISHES. 


471 


suspended  transversely  at  distances  of  about  'S  mm.  One  surface  of  the 
disc  is  directed  forwards,  and  is  flat ;  while  the  other  looks  backwards, 
is  slightly  concave,  and  shows  a  number  of  little  alveolar  depressions. 
One  of  these  discs  is  shown  in  section  in  the  sketch  in  Fig.  315.  Upon 
the  flat  surface  of  the  disc  is  the  nervous  membrane  which  in  structure 
corresjjonds  to  a  nerve-endplate  in  muscle.  The  alveoli  on  the  posterior 
surface  are  occupied  by  capillary  l)lood-vessels,  but  these  do  not  pene- 
trate the  disc.  The  substance  of  the  disc,  underneath  the  nerve 
membrane  (electric  membrane),  consists  of  fine  laminae,  parallel  to  its 
surface,  which  are  seen  in  section  as  striae.  But  towards  its  posterior 
surface  it  consists  apparently  of  structureless  material,  beset  -with 
numerous  nuclei." 


Fio.  315. — Semi-diagrammatic  view  of  a  disc  from  the  electric  organ  of 
the  skate,  o,,  a,  connective  tissue  with  capillaries  ;  b,  nerve  layer,  nerve 
endings  branching  dichotomously,  the  terminal  branches  all  tendintr  in 
the  direction  of  the  arrow  ;  e,  striated  layer,  which  corresponds  to  the 
bacillated  substance  of  g5'miiotus ;  d,  d,  processes  of  transparent  struc- 
tureless material,  containing  numerous  nuclei,  'corresponding  to  the 
thorn  papillae  of  a  gymnotus. 


The  electric  organ  in  the  skate  thus  resembles  that  of  the  gymnotus. 
The  organs  are  supplied  by  nerves  coming  from  the  ventral  or  motor 
roots  of  the  spinal  nerves,  and  these  run  along  with  the  motor  nerves 
going  to  the  muscles  of  the  tail.  I  am  not  aware  of  the  existence  of 
special  nerve  cells  in  the  spinal  cord. 

5.  The  General  Electrical  Properties  of  the  Electric  Fishes. — The  general 
phenomena  of  the  electric  fishes  may  be  illustrated  by  considering  in 
the  first  place  some  of  those  manifested  by  the  torpedo.  The  shock 
emitted  by  the  torpedo  is  weak  compared  with  that  of  the  malapterurus, 
but  as  pointed  out  by  Du  Bois-Reymond  the  strength  of  the  shocks  of 
the  torpedo  is  much  diminished  by  the  good  conductivity  of  the  sea  water 
by  which  the  fish  is  surrounded.  The  shock  of  the  torpedo  is  weaker 
because  less  current  passes  to  the  person  touching  it.     When  a  livin"- 


472  THE  CONTRACTILE  TISSUES. 

malapterurus  was  placed  in  salt  solution  its  shocks  became  much  weaker, 
indeed  Du  Bois-Reymoiid  states  "  it  apparently  lost  its  electrical  pro- 
perties." When  the  living  torpedo  is  touched  it  may  or  it  may  not  emit 
a  shock,  and  it  soon  becomes  evident  that  the  discharge  is  to  a  certain 
extent  under  the  control  of  the  will.  If  the  brain  be  removed  without 
injuring  the  electric  lobes,  irritation  of  one  or  other  of  these  lobes  will 
cause  an  electric  discharge  limited  to  the  side  corres})onding  to  the 
organ  irritated.  The  electric  lobes  are  thus  undoubtedly  the  electric 
centres.  These  may  be  also  excited  by  reflex  action,  that  is  to  say,  an 
irritation  of  the  skin  may  cause  a  reflex  discharge,  the  impression  being 
carried  to  the  nerve  centres  from  the  part  of  the  skin  irritated  by  the 
sensory  nerves  supplying  that  part,  and  on  reaching  the  electric  lobe 
charges  are  set  up  therein  which  resiilt  in  the  transmission  of  an  excita- 
tory change  along  the  electric  nerves  to  the  electric  organ.  Finally,  irrita- 
tion of  the  electric  nerves  themselves  causes  shocks,  but  these  are  weak 
in  comparison  with  those  obtained  by  directly  irritating  the  electric 
lobe.  The  reflex  "discharge"  of  the  fish  Avas  found  by  Marey  to  consist 
of  a  succession  of  shocks.  He  led  the  current  of  the  organ  through  a 
delicate  chronograph,  and  during  the  reflex  activity  of  the  organ  this 
vibrated,  thus  recording  the  rate  of  the  shocks  making  up  the  discharge. 
In  fresh  fish  the  rate  varied  from  as  many  as  200  a  second  to  70  a  second : 
but  it  soon  sank  to  20,  and  finally  to  only  1  or  2  per  second,  owing  to 
the  exhaustion  of  the  nervous  centres.  The  latent  period  of  the  dis- 
charge is  at  least  y^",  as  shown  by  recent  experiments  of  Gotch  upon 
the  discharge  in  curarized  torpedoes. 

Each  individual  excitatory  state  of  the  organ,  the  repetition  of  which 
makes  up  the  discharge,  may  be  evoked  in  a  cut-out  portion  of  organ 
by  mechanical,  chemical,  or  electrical  stimulation  of  its  nerve.  There 
is  a  distinct  interval  of  time  between  such  nerve  stimulation  and  the 
electromotive  response  of  the  organ.  This  is  partly  accounted  for  by 
the  slow  transmission  of  the  excitatory  process  from  the  jjoint  of  stimu- 
lation down  the  nerve  trunk,  the  rate  of  transmission  being  only  5  to  7 
metres  per  second.  Besides  this,  however,  there  is  a  true  latent  period, 
the  duration  of  Avhich  is  dependent  upon  the  temperature,  etc.,  of  the 
organ,  but  which,  ixnder  the  most  fiivourable  conditions,  is  not  less  than 
two"-  The  response  after  this  interval  begins  very  abruptly,  develop- 
ing a  high  electromotive  force,  and  then  subsides  at  first  rapidly,  and 
subsequently  more  slowly,  its  total  duration  amounting  to  about  tw"- 
The  discharge  is  therefore  analogous  to  tetanus  of  a  muscle  and  the  indi- 
vidual shocks  composing  it  to  the  individual  short  '  twitches  '  of  a  muscle. 
Physical  conditions  aff"ect  the  organ :  thus,  heating  to  22°  C.  stimulates  the 
organ  Avhile  cooling  makes  it  less  active.     The  administration  of  strychnia 


THE  PHENOMENA  OF  THE  ELECTRIC  FISHES.  473 

to  a  torpedo  causes  the  fish  to  emit  a  rajDid  series  of  shocks,  by  which  it 
soon  becomes  exhausted.  It  is  remarkable  that  the  response  of  the 
organ  to  excitation  of  its  nerve  is  not  in  any  way  affected  by  curare. 
This  was  shown  by  Moreau  in  1862,  and  the  recent  experiments  of 
Gotch  (ProceediiH/s  of  Physiological  Society,  1888)  fully  confirm  his  conclu- 
sions. The  reaction  of  the  organ  at  rest  is  neutral  but  it  becomes 
acid  by  activity.  Moreau  has  succeeded  in  charging  a  Leyden  jar  by 
the  shocks  of  a  torpedo. 

In  a  recent  research  on  the  electrical  organ  of  torpedo/  Mr.  Francis  Gotch 
arrives  at  the  following  conclusions — 

In  the  active  state,  the  ventral  surface  of  each  plate  becomes  negative  to  the 
dorsal  surface,  and  the  efifect  is  summed  up  so  that  the  dorsal  end  of  a  column 
becomes  positive  to  the  ventral  end.  The  electromotive  activity  of  the  organ  may 
be  produced  in  at  least  three  different  ways,  and  then  shows  itself  (a)  as  the 
response  of  the  organ  to  excitation  of  its  nerves,  whether  reflex  or  direct,  this 
nerve-organ  response  being  characterized  by  a  short  period  of  delay,  a  very 
rapid  development,  and  a  less  rapid  decline  ;  [h)  as  a  prolonged  after-effect 
following  the  passage  of  a  strong  cixrrent  through  the  substance  of  the  organ, 
and  which  therefore  follows  a  powerful  response  ;  and  [c)  as  a  prolonged  electro- 
motive change  following  mechanical  or  thermal  inji^ry  along  the  length  of  the 
columns  of  the  organ,  this  latter  being  the  electromotive  expression  of  a  prolonged 
local  excitatory  process  occurring  in  the  immediate  neighbourhood  of  the  injury. 

According  to  Pacini,  the  nerves  are  always  distributed  to  the  side  of 
the  electric  plate  which  becomes  negative  in  the  discharge.  This  law 
has  been  confirmed  by  all  later  researches.  In  the  torpedo,  therefore, 
as  the  nerves  are  in  the  lower  plate,  the  shocks  pass  from  the  belly  to 
the  back ;  in  the  gymnotus  the  posterior  surface  of  the  j^late  is  negative 
and  therefore  the  discharge  is  from  the  tail  to  the  head,  and  in  the 
malapterurus  the  negative  side  of  the  organ  is  anterior  and  thus  the 
current  passes  from  the  head  to  the  tail. 

An  electric  shock  may  be  obtained  from  the  gym,notns  by  touching  the 
fish  with  one  finger  or  with  a  conducting  substance  interposing  a  resist- 
ance similar  to  that  of  animal  tissue,  such  as  a  bit  of  wet  wood  or 
wet  leather.  Such  a  shock  is  slight  and  the  full  effect  is  obtained 
only  when  the  body  forms  part  of  a  complete  circuit  through  which  the 
greater  part  of  the  current  passes.  The  wider  apart  the  points  of  con- 
tact and  the  better  the  conducting  medium,  the  more  severe  is  the  shock. 
Dr.  Sachs  having  one  naked  foot  in  contact  with  the  head  and  the  other 
foot  with  the  tail  of  a  gymnotus  received  a  series  of  shocks  which  caused 
him  to  shriek  with  pain  and  stand  erect  as  if  petrified,  and  sometimes  a 
man  may  be  thrown  on  the  ground  by  a  single  shock.  Fishes  and  frogs 
^Fhil.  Trans.  1887,  p.  478. 


474  THE  CONTRACTILE  TISSUES. 

ill  the  water  along  with  a  gymnotus  are  killed  by  the  shock,  and  the 
electric  eel,  in  attacking  its  enemies,  throws  itself  into  an  arch  and 
touches  them  with  head  and  tail,  and  thus  gives  them  the  strongest 
possible  shocks  at  its  command.  If  the  current  is  sent  through  a  man's 
head,  he  sees  a  bright  flash  of  light.  As  already  stated,  the  current 
passes  in  the  fish  from  the  tail  to  the  head  and  any  point  of  the  surface 
of  the  fish  is  positive  to  any  posterior,  and  negative  to  any  anterior 
point.  The  fish  cannot  alter  the  direction  of  the  current,  but  it  can 
limit  the  amount  of  the  electric  organ  throAvn  into  action.  If  a  metallic 
circuit  is  made,  a  spark  may  be  obtained  on  brealcvu/  the  circuit  while  a 
current  is  passing,  but  a  spark  is  rarely  obtained  between  the  two  poles 
of  an  open  circuit.  The  ciUTcnt  will  not  illuminate  a  vacuum  tube.  It 
will  magnetize  a  needle.  It  is  remarkable  that  the  discharge  of  a 
gymnotus  will  not  pass  through  flame,  and  that  it  can  scarcely  be 
perceived  with  dry  copper  handles. 

If  a  section  of  the  electric  organ  of  a  gymnotus  be  laid  on  a  pair  of 
non-polarizable  electrodes  connected  with  a  galvanometer,  a  slight  cur- 
rent is  obtained.  The  organ  may  be  excited  to  action  by  mechanical, 
chemical,  or  thermal  stimuli.  The  organ  at  rest  is  alkaline  in  reac- 
tion ;  after  electrical  tetanus  or  that  produced  by  strj^chnia,  it  becomes 
neutral,  and  after  exjDosure  to  the  air  for  an  hour  or  two,  it  gives  an 
acid  reaction,  from  the  formation  of  lactic  acid.  The  time  of  the  electric 
discharge  is  about  equal  to  that  of  a  muscular  contraction. 

The  gymnotus  does  not  become  so  readily  fatigued  as  the  toi'pedo. 
Sachs  mentions  that  an  eel  which  in  the  course  of  an  hour  had  given 
about  150  discharges,  was  still  able  to  send  a  strong  shock  through  a 
circuit  or  chain  of  eight  persons,  the  first  of  whom,  touched  the  head  and 
the  last  the  tail. 

Du  Bois-Reymond  gives  a  very  interesting  account  of  the  malapterurux. 
Generally  the  fish  gives  one  or  more  discharges  on  being  touched,  but 
occasionally  it  maj-  not  give  a  shock,  even  in  escaping  from  the 
hand.  He  has  no  doubt  that  some  of  the  discharges  are  voluntary  and 
others  reflex.  Malapteruri  quickly  kill  other  fishes  by  electrical  dis- 
charges. A  frog  brought  into  contact  with  the  skin  is  tetanized.  As 
regards  the  strength  of  the  shock,  Du  Bois-Reymond  writes — ^ 

"In  comparison  with  its  size,  the  shock  of  the  malapterunis  is  surprisingly 
violent.  If  the  head  and  tail  of  a  powerful  fish  are  touched  with  the  fore-fingers 
in  the  water,  the  shock  does  not  extend  beyond  the  knuckles.     If  it  is  seized  with 

^  Du  Bois-Reymond,  "  Observations  and  Experiments  on  Living  Malapterurus." 
Burdon-Sanderson's  Biological  Memoirs.  Translation  by  Miss  Edith  Prance, 
p.  387. 


THE  PHENOMENA  OF  THE  ELECTRIC  FISHES.  475 

hands  thoroughly  wetted,  a  se\'ere  shock  is  felt  up  to  the  elbow.  If  it  is  touched 
with  one  hand,  a  pricking  sensation  is  experienced  in  the  skin,  a  burning  one  in 
wounds,  and  a  painful  shock  is  felt  in  all  the  joints  of  the  submerged  parts. 
The  best  way  to  take  the  shock  is  to  hold  with  wet  hands  ordinary  metal  handles, 
which  are  connected  with  the  linings  of  a  leading-otf  cover,  and  to  let  an  assistant 
put  this  on  the  fish.  As  one  is  accustomed  to  test  electric  shocks  in  this  way  and 
is  not  disturbed  by  anxiety  to  get  proper  hold  of  the  fish  without  hurting  it,  or  by 
the  feeling  of  repulsion  at  laying  hold  of  it,  one  can  better  judge  of  the  sensation 
caused  by  the  shock.  The  shock  does  not  seem  so  sharp  as  that  of  a  Leyden  jar. 
but  has  a  somewhat  swelling  character.  Several  maxima  may  be  frequently  dis- 
tinguished in  it.  By  sending  opening  shocks  of  an  induction  apparatus,  with  two 
Grove's  in  the  primary  circuit,  through  the  water  of  an  experimental  tub  by  means 
of  copper  plates  plunged  into  it,  having  first  approximated  the  secondary  coil  to 
the  primary  as  closely  as  possible,  the  shock  which  I  experienced  when  my  hands 
were  immersed  in  the  water  was  certainly  not  stronger  than  that  of  a  vigorous 
fish.  An  openmg  shock  with  the  coil  quite  pushed  in,  and  one  Grove  in  the  circuit, 
taken  directly  through  the  handles,  has  about  the  same  strength  as  such  a  shock." 
Mr.  Francis  Gotch,  in  a  communication  to  the  Physiological  Society,^  states 
"that  a  malapterurus  gave  to  the  fingers  a  smart  shock  which  became  un- 
pleasantly severe  when  both  the  head  and  tail  were  touched,  and  these  seemed 
comparable  wnth  the  break  shock  of  a  Du  Bois-Reymond  coil,  with  three  Daniell 
cells  in  the  primary  circuit  and  with  the  secondary  coil  pushed  quite  up.  A  shock 
could  also  be  obtained  by  placing  the  fingers  in  the  water  surrounding  the  fish  and 
then  exciting  the  animal  mechanically." 

The  discliarge  of  the  malapterurus  effects  the  electrolysis  of  iodide  of 
potassium  but  it  does  not  decompose  water.  Xo  sparks  could  he 
obtained  from  the  discharge  although  the  interval  between  the  metallic 
conductors  were  as  small  as  '01  mm.  Du  Bois-Reymond  also  made  slits 
in  tinfoil  not  wider  than  -0033  to  'OOS  mm.,  and  no  spark  across  the 
slit  was  noticed.  On  the  other  hand  the  secondary  current  of  the  in- 
duction coil  passed  over  this  slit  when  the  secondary  was  90  mm.  from 
the  primary  coil,  and  yet  these  induction  shocks  could  not  be  perceived 
by  the  tongue.  The  difference  between  the  behaviour  of  the  fish  and  of 
the  inductorium  is  due  to  the  fact  that,  in  the  case  of  the  fish,  most  of 
the  current  is  short-circuited,  and  the  shock  is  only  obtained  by  deriva- 
tion. Du  Bois-Reymond  -  puts  the  matter  thus  :  Suppose  two  ecjual 
currents,  la  and  Ih,  flowing  into  two  conductors,  A  and  B,  with  resist- 
ance A.  Suppose  also  the  end  of  conductor  B  be  connected  to  a  side 
conductor  \,  while  A  forms  part  of  an  unbranched  circuit.  It  can  then 
be  shown  that  if  the  resistance  A  of  the  two  conductors  be  increased  by 
the  same  amount,  Ih  will  lose  more  in  strength  than  la ;  or  to  state  it  in 
another  form,  as  the  actual  resistance  in  both  circuits  increases,  the 
difference  in  favour  of  the  current  in  the  conductor  A  (that  is,  the  un- 

^  Proceedin(js  of  the  Physiological  Society,  12th  December,  1885. 
-  Du  Bois-Reymond,  oj).  cit.  p.  394. 


47G  yV7£'  CUSTllACTILE  TISSUES. 

liranched  circuit)  increases.  Hence,  in  experimenting  with  the  fish,  it 
is  important  to  have  the  resistance  of  the  external  or  ex{)erimental 
tircuit  as  small  as  possible.  To  obtain  sparks,  the  circuit  must  be 
suddenly  opened  when  the  shock  is  strongest.  Du  Bois-Eeymond 
.-succeeded  in  passing  the  discharge  of  the  fish  through  the  primary 
coil  of  a  Ruhmkorff's  inductorium,  so  that  a  shock  AA'as  emitted  by  the 
secondary  coil.  Three  shocks  of  a  malapterurus  magnetized  needles 
37  mm.  long  by  •?  mm.  thick,  when  placed  in  the  central  cavity,  8  mm. 
wide,  of  a  coil  of  735  turns  of  copper  ware  -4  mm.  thick. 

Any  point  of  the  organ  nearer  the  tail  is  2:)ositive  to  any  point  nearer 
the  head,  and  the  intensity  of  the  shocks  increases  according  to  the 
distance  at  which  electrodes  leading  off  a  current  are  applied. 

It  is  remarkable  that  the  shocks  emitted  by  the  electrical  organ  pass 
through  the  body  of  the  fish,  and  that  the  accumulated  discharges  strike 
the  central  cerebro-spinal  system  vertically  to  its  axis.  This  of  course 
leads  to  the  c|uestion  of  how  far  the  nervous  organs  of  the  fish  arc 
-sensitive  to  electric  shocks.  Du  Bois-Eeymond  found  that  induction 
shocks  from  an  inductorium,  ha^dng  two  Grove's  elements  in  the 
primar}'  circuit,  killed  or  rendered  unconscious  such  fishes  as  tench, 
perch,  chuli,  pike,  and  silui'us,  and  the  same  current  tetanized  frogs, 
l)ut  a  malapterurus  was  apparently  unaflfected.  When  the  induction 
•shocks  were  made  much  stronger,  the  fish  noticed  them,  Imt, 

"  If  it  came  in  the  ueighboui-hood  of  the  electrodes,  where  the  current  densitj' 
was  greatest,  it  withdrew  hastily,  gave  a  shock  or  two,  and  sought  with  correct 
instinct  that  position  iii  which  its  axis  of  length  cut  perpendicularly  the  least 
dense  current  curves,  as  if  it  knew  the  laws  of  the  distribution  of  current  in 
non-prismatic  conductors."  -^ 

A  constant  current  from  30  Grove's  cells  did  not  appear  seriously  to 
inconvenience  the  fish,  but  here  also  "it  sought  that  position  which  is 
theoretically  the  most  protected."  These  experiments  clearly  show- 
that  malapteruri  have  a  certain  immunity  from  electric  shocks,  and  that 
they  do  not  suffer  from  their  own  discharges.  Xow,  if  Ave  consider 
that  sensor}'  nerves  require  a  certain  strength  of  stimulus  to  excite 
them,  and  that  electrical  currents  produce  peculiar  effects  on  nerves,  it 
is  clear  that  the  lower  limit  at  which  excitation  occurs  is  higher  for  the 
nerves  of  malapteriu'us  than  for  the  nerves  of  other  animals. 

When  the  electric  nerve  is  directly  irritated,   a  number  of  rapid 

shocks  are  emitted,  so  that  if  the  nerve  of  a  nerve-muscle  i^rejiaration 

(Fig.  261,  p.  401)  is  laid  on  the  organ  on  the  side  corresponding  to  the 

electric  nerve  irritated,   the  nuiscle    of  the  preparation  is  tetanized. 

1  Du  Bois-Eeymond,  op.  c'lt.  p.  -400. 


THE  PHENOMENA  OF  THE  ELECTRIC  FISHES.  477 

Du  Bois-Eeymond.  failed  to  get  evidence  of  a  current  from  the  electric 
nerve  when  it  was  placed  on  the  cushions  of  the  galvanometer 
(Fig.  294,  p.  447),  nor  did  he  observe  any  negative  variation  when 
it  was  irritated,  but  the  nerve  Avith  which  the  experiment  was  made 
was  in  a  very  exhausted  condition  (removed  2|  hours  after  the  circula- 
tion had  ceased),  and  he  states  that  "it  is  conceivable  that  a  more 
efficient  electrical  nerve  of  the  malapterurus  might  show  traces  on  the 
galvanometer  of  the  nerve-current  and  of  its  negative  variation." 

Mr.  Francis  Gotch,^  in  his  observations  on  a  malapterurus,  in 
which  he  used  both  the  galvanometer  and  the  capillary  electrometer, 
made  the  important  discovery  that  the  discharge  on  electrical  excitation 
of  the  skin  is  not  of  a  reflex  character,  but  is  the  result  of  a  direct 
excitation  of  the  electrical  organ  at  the  point  irritated  by  a  break 
induction  shock  with  1  Daniell's  element  in  the  primary  circuit  and 
the  secondary  coil  80  mm.  or  less  from  the  primary.  In  these  circum- 
stances the  latent  period  is  extremely  short.  Further,  the  molecular 
disturbance  set  up  at  the  point  irritated  is  propagated  through  the 
electrical  organ  at  the  rate  of  about  2-5  metres  per  second.  When  the 
fish  was  irritated  by  a  single  induction  shock  on  "  the  dorsal  surface 
between  the  eyes,"  a  long  discharge  took  place,  causing  tetanus  of  a 
nerve-muscle  preparation  in  contact  with  it,  the  individual  contractions- 
of  which  were  at  the  rate  of  10  per  second. 

As  regards  the  electrical  phenomena  of  the  skate,  Dr.  Burdon- 
Sanderson  has  communicated  to  me  the  following  facts — 

The  direction  of  the  discharge  is  towards  the  tail,  that  is  to  say,  it  is  such  that 
at  the  moment  of  activity  the  ends  of  the  electric  nerves  become  positive  to  the 
trunks,  in  accordance  with  the  law  of  Pacini.  The  discharge  may  be  induced 
in  the  living  animal  by  mechanical  stimulation  of  the  surface  of  the  body, 
and  then  consists  of  a  rapid  siiccession  of  similar  instantaneous  eifects.  In  the 
separate  organ  the  anterior  end  is  negative  to  the  posterior,  that  is,  there  is  an 
"organ  current"  in  the  same  direction  as  the  discharge.  This  difference  of 
potential  is  increased  enormously  by  increase  of  temperature  or  by  injuring  the 
surface.  The  electromotive  force  of  the  discharge  relatively  is  far  inferior  to  that 
of  torpedo  in  its  most  active  state.  The  discharge  can  be  heard  by  the  telephone, 
but  cannot  be  felt  by  the  fingers. - 

6.  Special  Electrical  Phenomena  of  the  Electric  Fishes. — Du  Bois- 
Reymond  and  Sachs,  and  more  especially  the  former,  have  discovered  a 
number  of  phenomena  which  are  of  profound  interest,   but  some  of 

^  Francis  G-otch,  Proceeding-'i  of  Physiological  Society,  op.  cit.  xxviii. 
■^  Goodsir  communicated  to  Du  Bois-Reymond  the  suggestion  that  the  electrical 
organ  of  the  skate  is  active  only  during  sexual  excitement. 


478  THE  COi^TltACTlLE  TISSUES. 

which,  from  their  very  nature,  are  difficult  of  explanation.  Thus  ])u 
Bois-Keymond  has  investigated  the  distribution  of  the  current  in  the 
torpedo,  and  has  shown  that  the  shock  })enetrates  the  hody  of  the  fish 
and  attains  a  greater  density  in  the  brain  and  spinal  cord  than  else- 
where. The  currents  floAving  in  the  back  from  the  bordei's  of  the  organ 
to  the  mesial  line,  and  in  the  belly  from  the  mesial  line  to  the  borders, 
pass  through  the  brain  and  cord,  as  this  "  is  the  shortest  path  between 
the  most  active  portions  of  both  organs."  The  greater  the  length  of  a, 
column  in  torpedo  (the  number  of  plates  being  constant  in  a  unit  of 
length)  the  greater  is  its  electromotive  force.  As  the  columns  arc 
longest  in  the  median  region  of  the  organ,  the  electromotive  force  of 
these  columns  is  greater  than  that  of  the  lateral  columns.  Hence,  in 
air,  a  current  flows  in  the  back  from  the  middle  of  the  organ  to  the 
borders,  and  in  the  belh^  in  the  reverse  direction.  In  salt  Avater, 
however,  the  currents  of  the  higher  cohmms  have  nearly  the  same 
strength  as  those  of  the  shorter  ones.  If  all  the  cohimns  in  both 
organs  were  of  the  same  length,  and  if  the  organs  Avere  united  in  the 
middle  plane,  then  the  most  positive  part  avouIcI  be  "  the  middle  of  the 
median  line"  on  the  back,  and  the  most  negative  the  corresponding 
part  on  the  ventral  aspect.  When  the  organs  are  separated,  then  the 
most  positive  part  is  nearer  the  inner  than  the  outer  border,  in  con- 
secpience  of  the  thinning  of  the  organ  toAvards  the  sides.  Hence  the 
inner  border  is  most  positive  dorsally,  and  most  negative  ventrally,  and 
therefore  a  current  floAvs  in  the  l:)ack  from  the  outer  border  to  the 
middle  line,  and  in  the  belly  in  the  reverse  direction.  Further  Du 
Bois-Reymond  has  shoAvn  that  the  curves  of  the  direction  of  the  currents 
passing  out  from  the  dorsal  surface  through  the  Avater  and  back  to  the 
ventral  surface  are  inclined  outAA^ards,  and  also  that,  in  consequence  of 
the  greater  inclination  of  the  median  columns,  by  making  the  current 
curves  still  more  oblique,  the  dorsal  surface  of  the  fish  Avhen  it  lies  half 
buried  in  mud  at  the  bottom  of  the  sea  is  more  protected  electricallj- 
than  the  ventral  surface  which  does  not  require  protection. 

By  the  organ  current  is  understood  a  current  existing  in  the  organ 
during  rest  and  passing  in  the  direction  of  the  shock.  Such  a  current 
exists  in  all  electrical  fishes.  Thus,  in  the  torpedo,  on  applying  the 
cushions  of  the  galvanometer  to  the  dorsal  and  ventral  sides,  after  the 
electric  lobe  of  the  brain  had  been  destroyed,  so  as  to  remove  from  the 
animal  the  poAver  of  giving  voluntary  electric  shocks,  a  current  Avas 
readily  passed  through  the  coils  of  the  galvanometer.  By  another 
method,  Du  Bois-Reymond  AA^as  able  to  examine  bundles  of  columns  of 
the  length  of  29  mm.,  and  Avhcn  these  Avere  placed  on  the  electrodes  so 
that  one  electrode  touched  the  end  and  the  other  the  side  of  the  column, 


THE  PHENOMENA  OF  THE  ELECTRIC  FISHES.  479 

a  current  was  obtained.  The  current  thus  obtained  from  bits  of  the 
organ  of  torpedo  was  remarkably  small,  "considerably  less  than  the  force 
of  the  nerve-current  in  frogs."  ^  Sachs  obtained  from  bits  of  the  organ 
of  a  gymnotus  40  mm.  long,  an  e.  m.  f.  of  from  '01 5  to  -030  (mean, 
•0225)  of  that  of  a  Daniell's  element.  With  strips  of  the  organ  of 
torpedo  29  to  12  mpi,  (mean,  20  mm.),  Du  Bois-Reymond  obtained 
•0085  of  a  Daniell's  element.  Double  this  would  have  been  -017,  thus 
a  little  less  than  that  of  a  gymnotus.  He  also  shows  that  the  e.  m.  f. 
of  a  single  plate  of  gymnotus  is  about  -00006  of  a  Daniell's  element, 
while  that  of  a  single  plate  of  torpedo  is  only  -0000117  of  a  Daniell's 
element,  or  about  3-3  times  less  than  that  of  gymnotus.'^  The  torpedo 
is  a  sea-water  fish,  Avhile  the  gymnotus  inhabits  fresh  water,  and  it  is 
remarkable  that  the  ratio  of  the  e.  m.  f.  in  the  two  fishes  is  almost  the 
same  as  that  of  the  resistance  of  fresh  water  to  salt  water.  (Christiani.) 
Each  plate  of  the  fresh-Avater  fish  has  a  larger  e.  m.  f.  than  that  of  the 
sea-water  fish  because  it  has  a  greater  resistance  to  overcome. 

The  organ  current  decreases  as  the  organ  dies,  but  in  the  cold  it  may 
remain  for  24  or  48  hours  after  the  death  of  the  fish.  Strips  of  the 
electric  organ  of  a  malapterurus  have,  in  the  hands  of  Du  Bois- 
Reymond,  yielded  no  organ  current,  but,  as  he  suggests,  this  may  be 
owing  to  the  weakness  of  the  animals  under  investigation. 

Du  Bois-Reymond  has  made  a  number  of  remarkable  observations  on 
the  polarizing  effects  produced  by  passing  currents  through  the  organ  of 
the  torpedo.  In  this  way  polarization  currents  are  produced.  If  the 
polarizing  currents  are  in  the  direction  of  the  natural  shock-current  of 
torpedo,  as  it  runs  in  the  body  of  the  animal,  that  is  from  belly  to 
back,  they  are  termed  homodromous,  and  if  in  the  opposite  direction 
to  that  of  the  natural  shock-current,  that  is  from  back  to  belly,  he 
calls  them  heterodromous.  "  Polarization  eff'ects  from  belly  to  back  are 
absolutely  positive,  and,  according  as  they  follow  an  absolutely  positive 
or  negative  polarizing  current,  they  may  be  considered  relatively  posi- 
tive or  negative."  The  character  of  the  polarization  efiect  seems  to 
depend  on  the  length  of  the  time  of  closing.  Thus,  with  homodromous 
currents,  a  long  closing  time  gives  a  polarization  relatively  negative, 
while  a  short  closing  time  gives  a  polarization  relatively  positive.  As 
functional  activity  diminishes,  positive  polarization  disapj^ears  and  then 

^  Du  Bois-Eeymond — Burdou -Sander-son's  Translations,  o^).  cit.  p.  441. 

2  The  e.  m.  f.  between  the  longitudinal  and  transverse  section  of  the  gastroc- 
nemius of  a  frog  is  about  -03  to  '08  Daniell,  and  that  between  the  longitudinal 
and  transverse  section  of  a  sciatic  nerve  of  a  frog  about  -02  Daniell.  Burdon- 
Sanderson  found,  on  an  average,  an  e.  m.  f.  between  the  lobe  of  the  leaf  of  JDiomea 
muscijnda  and  the  mid  rib  of  '006  Daniell. 


480  '^iiE  COS  TRACTILE  TISSUES. 

only  negative  polarization  remains.  With  homodromous  currents 
polarization  may  be  in  two  directions,  first  relatively  negative  and  then 
relatively  positive.  Since  shocks  of  very  short  duration  polarize  posi- 
tively, the  strength  of  the  normal  shock  of  the  organ  may  be  itself  in- 
creased. From  these  and  other  observations  Du  Bois-Reymond  infers 
that  "the  strength  of  the  homodromous  current  is  so  much  gi-eater  than 
that  of  the  heterodromous  that  the  relatively  positive  heterodromous 
polarization  is  constantly  masked  by  the  relatively  negative."  As  early 
as  1857,  Du  Bois-Reymond  observed  this  law  in  experimenting  "wdth 
fresh  strips  of  the  organ  of  malapterurus  "  in  which  positive  polarization 
appeared  in  full  force  in  the  direction  of  the  shock,  the  descending 
current  (homodromous  in  malapterurus)  Avas  always  greater  than  the 
ascending  (heterodromous)  in  the  relation  of  100  to  112,  116,  or  125, 
and  he  inferred  from  this  the  existence  of  a  polarization  current  which 
was  added  to  the  current  of  the  battery  passed  through  the  organ."  In 
some  of  his  more  recent  experiments  with  torpedo  he  found  the  strength 
of  the  homodromous  current  of  30  Grove's  elements  to  be  more  than 
tAvice  that  of  the  heterodromous  current.  The  e.  m.  f.  of  this  addi- 
tional polarization  current  must  be  assumed  to  be  high  when  the 
difference  between  the  effects  of  homodromous  and  heterodromous 
currents  is  so  great.  But  a  difference  of  current  strength  depends  not 
only  on  unequal  electromotive  forces,  but  on  unequal  resistances,  and 
hence  the  explanation  of  these  facts  may  be,  not  the  generation  of  a  new 
c.  m.  f.  bv  the  homodromous  ciuTent,  but  that  the  organ  conducts 
better  in  the  natural  direction  of  the  shock  cm-rent  than  in  the  reverse 
direction.  That  is  to  say,  the  resistance  is  greater,  in  the  organ  of 
torpedo,  in  the  doAvnward  than  in  the  upward  direction,  or  the  resist- 
ances are  irreciprocal.  This  irreciprocity,  or  inec(uality  of  resistance  in 
the  two  directions,  may  depend  on  some  peculiarity  of  the  organic 
molecules  during  life  as  it  gradually  disappears  as  the  organ  slowly 
dies,  or  it  may  at  once  be  removed  by  plunging  the  organ  into  boiling 
water.  In  later  researches,  Du  Bois-Reymond  found  that  the  irrecipro  • 
city  increases,  but  not  proportionally,  with  the  cuiTent  density,  or,  in 
other  words,  when  the  distance  of  the  secondary  coil  from  the  primary 
of  the  inductorium,  by  which  shocks  Avere  transmitted  through  the 
oro-an,  was  diminished  to  zero,  the  irrecipi^ocity  became  greater  than 
when  the  secondary  stood  100  mm.  from  the  primary.  At  100  mm.  the 
resistance  to  a  homodromous  current  to  that  of  a  heterodromous 
current  was  as  1-33  to  27-66,  giving  an  index  of  irreciprocity  of  -0481 
(that  is  1-33 -r  27-66),  while  at  zero  the  ratio  was  as  264*7  :  477,  or  an 
index  of  irreciprocity  of  -5549,  while  if  the  irreciprocity  had  been  in  direct 
proportion  to  the  current  density,  the  index  woidd  have  been  -8293. 


THE  PHENOMENA  OF  THE  ELECTRIC  FISHES.  481 

This  apparent  irreciprocity  exists  in  each  transverse  lamella  of  the  organ. 
A  careful  inquiry  into  the  conducti-vity  of  the  organ  of  torpedo,  enables 
Du  Bois-Eeymond  to  state  that — 

"  Even  in  the  homodromous  direction,  in  which  the  organ  conducts  best,  it 
conducts  scarcely  half  as  -well  as  frog  muscle  parallel  to  the  fibre,  and  7  "5  to  12 
times  worse  than  the  sea  water  of  the  aquarium.  The  ratio  would  be  still  more 
unfavourable  with  sea-water  from  the  Mediterranean,  which  conducts  nearly  150 
times  better  than  tap  water.  But  in  the  heterodromous  direction  the  organ  con- 
ducts even  20  to  58  times  worse  than  sea  water." 

In  summing  up  the  results  of  his  investigations  on  the  torpedo,  Du 
Bois-Eeymond  endeavours  to  show  the  important  part  played  by 
irreciprocal  conduction,  and  his  opinion  is  that  it  takes  the  place  of 
insulating   septa,   which   were   assumed   by  the   earlier   physiological 


Tig.  316. — Diagram  showing  the  current  curves  in  the  electrical  dis- 
charge of  torpedo. 

electricians  either  to  exist  permanently  around  the  organ  or  to  be  called 
into  existence  at  the  instant  of  the  discharge.  His  view  will  be  under- 
stood with  the  aid  of  the  diagram  in  Fig.  316.  Suppose  a  sino-le 
column  of  the  organ  of  a  torpedo  surrounded  by  a  conductino-  mass. 
The  current  curves  mil  issue  from  the  upper  end  and  pass  throuo-h  the 
conducting  mass  to  the  lower  end,  and  these  curves  will  be  symmetri- 
cally arranged  around  the  axis  of  the  column.  Suppose  also  the  column 
divided  into  an  upper  and  lower  portion  by  a  transverse  plane.  The 
part  above  the  transverse  plane,  0-0,  Fig.  316,  ^rill  be  the  positive  dorsal 
I.  2  H 


482  .  THE  CONTRA  CTILE  TISSUES. 

end  of  the  column,  and  the  part  l>elow  0-0  will  be  the  negative  ventral 
end.  All  the  curves  issuing  from  the  dorsal  end  will  pass  perpendicularly 
through  the  transverse  plane,  so  that  the  tension  of  this  plane  will  be 
zero.  In  the  column,  currents  will  flow  from  bell)-  to  back,  those  near 
the  axis  of  the  column  nearly  ])arallel  to  it,  while  those  nearer  the  lateral 
surfaces  are  more  divergent,  and  some  of  the  most  divergent  will  cut  the 
lateral  surface.  On  the  left,  the  figure  (Fig.  316)  shows  the  outermost 
system  of  curves  around  one  column  cutting  the  transverse  plane.  If 
now  a  second  column  be  placed  alongside  of  this  one,  the  current  curves 
on  the  two  halves  of  the  cohmins  in  apposition  will  be  compounded,  and 
so  with  a  third,  a  fourth,  or  an}'  number  of  columns  placed  side  by  side. 
Thus  the  density  of  the  current  in  1  will  be  doubled  by  that  of  2, 
trebled  by  that  of  3,  and  increased  7(-times  by  the  addition  of  n^^  column. 
Each  column  Avill  be  met  as  it  Avere  l>y  the  currents  of  the  others,  homo- 
dromously,  that  is,  in  the  direction  of  its  own  current.  Now  the  torpedo 
has  two  symmetrical  organs,  as  shown  in  Fig.  316,  in  which  D  V,  the 
sagittal  plane,  may  be  regarded  as  insulated.  Looking  at  the  left  of  the 
figure,  imagine  the  strip  "with  transverse  marks  to  represent  one  column, 
it  is  clear  that  the  currents  from  this  column  pass  heterodromously 
through  all  the  other  columns.  The  currents  issuing  from  the  axis 
of  the  column  pass  out  and  meet  the  small  fish  seen  in  the  diagram. 
The  little  fish  Avill  receive  a  shock  which  Avould  be  stronger  if  the  column 
under  consideration  were  insulated.  This  is  shown  in  the  right  of  the 
diagram,  when  the  shaded  portion  indicates  an  imaginary  arrangement 
for  insulation.  It  will  be  seen  that  a  larger  number  of  current  curves 
strike  the  little  fish  on  the  right  side  than  on  the  left.  The  insulation 
also  compels  currents  which,  on  the  left  side,  pass  through  part  of  the 
organ,  to  pass  on  the  right  side,  round  the  edges  of  the  organ.  Thus 
insulation  Avould  increase  the  action  of  an  electromotive  column  on  any 
part  of  external  space.  In  torpedo,  however,  the  columns  are  not 
insulated,  but  the  same  eff"ect  is  obtained  by  the  fact  that  all  the  currents 
passing  throiigh  the  organ  are  heterodromous,  in  which,  as  we  have 
seen,  the  resistance  is  much  greater,  and  consequentlj^  the  same  effect 
is  produced  as  if  the  columns  were  insulated.  That  is  to  say,  hy 
increasing  the  resistance  in  the  downAvard  direction,  the  density  of  the 
total  current  into  external  space  is  increased.  Each  column  conducts 
its  own  homodromous  current  but  offers  resistance  to  the  heterodromous 
currents  of  all  the  others,  and  consec[uently  the  heterodromous  currents 
are  forced  to  pass  round  the  edges  of  the  organ  as  if  it  were  composed 
of  a  non-conducting  substance.  The  part  of  the  animal,  however,  be- 
tAveen  the  median  borders  of  its  tAvo  electric  organs,  that  is  its  cerebro- 
spinal L!,xis,  is  traversed  by  the  strongest  floAV  of  current,  and,  Avith 


THE  PHENOMENA  OF  THE  ELECTRIC  FISHES.  483 

reference  to  this,  the  importance  of  the  fact  that  the  torpedo  and 
-electric  fishes  in  general  have  a  kind  of  immunity  from  the  effects 
of  electric  shocks  is  obvious. 

These  remarkable  results  of  Du  Bois-Reymond,  to  explain  which  he 
lias  advanced  the  beautiful  theory  above  set  forth,  have  not  been  un- 
questioned, and  in  a  communication  made  to  the  Royal  Society  by  Mr. 
Francis  Gotch,^  the  fact  of  the  existence  of  irreciprocal  conduction  in  the 
torpedo  has  apparently  been  disproved.  Du  Bois-Reymond's  method 
depended  on  observing  the  deflections  of  a  galvanometer  when  the 
polarizing  homodromous  or  heterodromous  currents  were  sent  through 
.a  strip  of  the  or-gan  and  also  through  the  circuit  of  the  galvano- 
meter. 

Gotch  discovered  that  intense  currents  of  short  dui'ation,  such  as 
Avere  used  by  Du  Bois-Reymond,  always  cause  "  an  excitatory  response  " 
in  the  tissue  of  the  electric  organ  ;  that  the  intense  current  du.e  to  this 
response  is  added  to  the  homodromous  current,  and  the  result  is 
that  the  latter  must  be  stronger  than  the  heterodromous.  Thus, 
calling  the  homodromous  cixrrent  a,  and  the  heterodromous  h,  and 
the  "  excitatory  response  current  "  of  Gotch  c,  when  a  short  strong  cur- 
rent passes  upwards  (homodromous),  the  result  is  a  +  c;  but  if  the 
short  strong  current  passes  do^vnwards  (heterodromous),  the  result  is 
h  —  c.  By  means  of  a  fast  moving  rheotome,  Gotch  Avas  enabled  to 
"  switch  in  "  the  induction  currrent  only,  and  then,  on  passing  it  in 
■either  direction,  upwards  or  downwards,  the  resistance  is  found  to  be 
the  same,  that  is  to  say,  there  is  no  irreciprocity.  The  apparent 
irreciprocity,  therefore,  is  an  excitatory  phenomenon,  not  due  to  a 
cliff"erence  in  resistance,  but  to  the  adding  or  subtracting  of  an  addi- 
tional electromotive  force. 

Mr.  Gotch  has  also  made  the  remarkable  discovery  that  the  organ 
may  be  excited  in  a  secondary  way  by  its  own  discharge.  Strong 
healthy  fish,  in  the  summer,  when  excited  by  one  irritation,  gave  not 
•only  a  first  discharge,  but  also  in  quick  succession  a  second,  third, 
fourth,  and  so  on  at  intervals  of  about  —^  of  a  second,  each  succes- 
sive shock  becoming  weaker  than  the  one  before  it.  Thus,  as  clearly 
.stated  by  Mr.  Gotch — 

"  The  response  of  the  isolated  organ  to  nerve  excitation  is  multiple  ; 
:a  primary,  secondary,  tertiary  response  following  the  application  to  the 
nerve  of  a  single  stimulus.  Since  all  these  responses  produce  currents 
similarly  directed  through  the  columns  of  the  organ,  each  column  during 

^  Francis  Gotch,  M.A.  Oxon.,  B.A.,  B.Sc.  Lond.  Further  observations  on  the 
■electromotive  properties  of  the  electrical  organ  of  torpedo  marmorata.  Eead  before 
the  Royal  Society,  March  9th,  1888. 


484 


THE  CONTRACTILE  TISSUES, 


its  activity  must   reinforce   by  its  echoes  the  force  of  the   primary 
explosion,  both  in  its  own  substance  and  also  in  that  of  its  neighbours." 

The  brief  account  I  have  given  of  the  electric  organs  indicates  that 
such  investigations  Avill  probably  throw  light  on  the  obscure  relations 
that  exist  between  nerves  and  muscle  and  other  terminal  organs.     In 

the  case  of  torpedo,  gymnotus,  and  raia,  the 
nerve  termination  is  evidently  analogous  to 
a  motorial  end-plate  in  muscle  (Fig.  317)^ 
and  in  malapterurus  to  the  terminations  of 
nerves  in  the  cells  of  glands  (Fig.  318).  The 
nerve  stimulus,  or,  as  it  may  be  put,  the 
molecular  disturbance  transmitted  along  a 
nerve  causes  changes  in  its  end-organ,  and 
these  are  propagated  to  the  surrounding 
substance.  These  changes  are  associated 
vnth  a  change  of  potential,  and  the  part 
becomes  negative.  A  wave  of  negativity 
passes  through  the  organ,  and  then  there  is. 
probably  a  physiological  result  according  to 
the  kind  of  organ  in  Avhich  the  changes  may  take  place.  If  it  be  a 
muscle,  the  chief  expression  of  the  change  is  a  variation  in  form  or 


FiG.  317.— Pictorial  end-plate 
in  muscle,     n,  nerve. 


Fig.  318.— Mode  of  nerve-terminations  in  glands,  according  to  Pfliiger. 
I.  Xerve  ending  in  a  group  of  cells,  but  not  apparently  uniting  -with  any 
of  them.  II.  Nerve  sending  branches  between  cells.  III.  Nei-ve  fila- 
ments apparently  continuous  with  substance  (nucleus?)  of  cells. 
IV.  Ganglionic  nerve  cell,  with  process  passing  to  seci-eting  cell. 
Pfluger's  observations  have  not  been  confirmed.  Kupfifer  describes  a 
similar  arrangement  in  the  salivary  gland  of  insects,  and  JIacallum 
believes  he  has  traced  nerve-endings  into  the  cells  of  the  liver. 


TEE  PHENOMENA  OF  THE  ELECTRIC  FISHES.  485 

■contraction ;  if  it  be  a  gland  cell,  the  chief  expression  of  the  change  is 
the  formation  of  certain  matters  or  metabolism ;  and  if  it  be  an  electrical 
•organ,  it  is  an  electrical  discharge.  In  all  these,  however,  similar 
phenomena  occur,  but  to  varying  amounts.  Thus,  call  contraction  a, 
■electromotive  phenomena  h,  and  metabolic  changes  c.  In  a  muscle,  a  is 
large,  and  h  and  c  relatively  small ;  in  a  gland,  a  probably  does  not 
•occur  as  an  active  contraction,  although  the  cell  may  slowly  change  in 
form  and  bulk ;  h  is  also  small,  but  c  is  relatively  large  ;  and  in  an 
electrical  organ,  there  is  no  evidence  that  a  occurs,  h  is  largely  shown, 
and  c  is  relatively  small.  Thus,  all  these  phenomena  are  linked 
together,  and  as  our  knowledge  advances  into  the  molecular  processes 
■of  the  one,  it  is  likely  soon  to  shed  light  on  the  other  two. 

Finally,  I  cannot  help  remarking  that  in  few  departments  of  physio- 
logical science  can  more  striking  examples  of  internal  adaptation  be 
found  than  in  the  construction  and  place  in  nature  of  the  electric  fishes. 
As  "v^Titten  by  Du  Bois-Eeymond,  we  have  in  them  "  surprising 
instances  of  that  organic  adaptiveness,  which  is  an  ever-new  source  of 
wonder  even  to  the  strict  adherent  of  mechanical  casuality."  It  seems 
to  me, — again  using  a  phrase  of  the  distinguished  Berlin  physiologist, — 
that  if  any  human  imitation  of  the  electrical  mechanism  of  a  torpedo 
or  gymnotus  could  have  been  the  outcome  only  of  the  "profoundest 
reflection  of  a  clever  brain,"  even  so  we  can  account  for  such  adapta- 
tions only  by  assuming  an  intelligent  consciousness  acting  behind  natiu-al 
phenomena. 

Consult  as  to  the  older  views  of  the  nature  of  electric  organs  : — John  Goodsir's 
Anatomical  Memoirs,  vol.  II.  p.  289  et  seq.  As  to  the  more  modern  histology  : — 
E,ANViER,  Histologie  du  Systeme  Nerveux,  vol.  II.  p.  157  et  seq.  ;  Carl  Sachs, 
Unterstichungen  am  Zitteraal  (Gymnotus  electricus),  1881  ;  Gustav  Fritsch, 
Das  Gehirn  unci  RiicJcenmarh  des  Gymnotus  electricus,  1881  ;  Gustav  Fritsch, 
Die  elelctrischen  Fische,  erste  Abth.  Malapterurus  electricus,  1887;  August  Ewald, 
ilher  den  Modus  der  Nervenvtrhreitung  im  elelctrischen  Organ  von  Torpedo,  1881. 
As  to  electro-physiology,  see  the  Translations  of  Du  Bois-Reymoxd's  Memoirs  in 
Burdon-Saxderson's  Biological  Memoirs,  1S87  ;  also,  Paper  by  Du  Bois- 
Keymond  in  Carl  Sach's  volume  above  mentioned  ;  Papers  by  Burdon-Saxder- 
SON  and  GoTCH,  communicated  to  the  Royal  Society,  already  referred  to,  1887-88  ; 
and  Paper  by  Gotch,  at  the  end  of  which  is  an  excellent  bibliography,  on  the 
electromotive  properties  of  torpedo  marmorata,  Phil.  Trans,  vol.  178  (1887)  B, 
pp.  487-537. 


487 


APPENDIX  I. 


Regarding  Reagents,  see  p.  260  ■  Modes  of  Isolation,  p.  265  ;  Modes 
of  Fixing,  p.  266;  Hardening,  p.  268;  Decalcification,  p.  268;  Staining, 
p.  270 ;  and  Investigation  of  Fresli  Objects,  p.  276.  By  the  following 
methods  preparations  may  be  made  similar  in  character  to  those  repre- 
sented in  the  page  or  pages  referred  to  under  each  method — 

SPECIAL  METHODS  OF  MAKING  HISTOLOGICAL  PREPARATIOXS. 

1.  Nuclei,  Method  No.  1,  p.  206.  The  reticulum  in  nuclei  can  be  readily  seen 
in  the  cells  in  the  skin  of  the  larvae  or  tadpoles  of  amphibia.  The  larvse  of  the 
triton  or  newt  are  easily  procured  in  the  months  of  June  or  July.  [Dr.  Macallum, 
of  University  College,  Toronto,  informs  me  that  the  phenomena  may  be  readily 
studied  in  the  epithelial  cells  of  the  skin  of  Kecturus.]  Fresh  specimens,  3  to  4 
cm.  long,  are  thrown  into  20  c.cm.  of  chromo-osmium-acetic  acid  (p.  261),  in  which 
they  quickly  die.  After  one  or  two  days,  cut  from  the  tail  a  portion,  1  c.cm.  long, 
or  peel  off  a  bit  of  skin  from  the  tail  with  the  forceps.  Scrape  off  with  a  scalpel 
some  of  the  epithelium;  the  remainingthin  portion  of  skin  is  hardened  in  50  c.cm. 
of  alcohols  of  gradually  increasing  strengths  (p.  267),  colour  in  saffranin  (p.  263), 
and  mount  in  dammar  varnish.  Striated  muscles  of  the  tail,  and  involuntary 
muscle  from  the  intestine,  also  give  beautiful  results  by  the  same  process.  See 
also  p.  271,  par.  3. 

2.  Karyokinesis,  Method  No.  2,  p.  213.  Place  for  two  days  portions  of  the 
anterior  segment  of  the  eyes  of  young  newts  in  chromo-osmium-acetic  acid  (p.  261), 
wash  thoroughly  in  water,  and  harden  in  alcohol  of  gradually  increasing  strengths 
(p.  267).  Two  days  later,  cut  out  the  cornea,  and  pull  off  with  the  forceps  a  thin 
lamina  of  corneal  tissue.  Colour  in  saffranin  (p.  263),  and  mount  in  dammar 
varnish,  so  that  the  convex  side  of  the  cornea  is  directed  upwards.  The  nuclei 
are  stained  red,  and  with  high  powers  karyokinetic  forms  will  be  seen. 

3.  Testis,  Method  No.  3,  p.  215.  Divide  into  two  equal  portions  by  a  trans- 
verse cut  the  testis  of  a  young  human  subject,  and  fix  both  portions  in  50  c.cm.  of 
Kleinenberg's  sulpho-picric  acid  (p.  261),  then  harden  in  30  c.cm.  of  alcohols  of 
gradually  increasing  strengths  (p.  267).  Colour  thick  transverse  sections  with 
carmine  (p.  2C2)  and  with  hematoxylin  (23,  p  262),  and  mount  in  dammar 
varnish. 

4.  Ttjbuli  Seminiferi,  Method  No.  4,  p.  216.  fix  portions,  2  cm.  broad,  of 
fresh  testis  of  ox  in  20  c.cm.  of  Mliller's  fluid  (p.  261),  and  at  the  end  of  fourteen 


488  APPENDIX  L 

days  transfer  them  to  alcohol  of  gradually  increasing  strengths  (p.  267).  Colour 
very  thin  sections  with  ha?inatoxylin  (p.  2(52),  and  mount  in  dammar.  The  smaller 
canals,  containing  developing  spermatozoids,  are  coloured  intensely  blue,  and  the 
nuclei  of  the  peripheral  cells  are  often  stained  more  deeply  than  the  nuclei  of  the 
cells  lying  near  the  lumen. 

5.  Spermatoblasts,  Method  Ko.  5,  p.  218.  Fi.x:  small  portions,  5  mm.  broad, 
of  testis  of  ox  newly  killed  in  10  c.cm.  of  chromo-osmium-acetic  acid  (p.  261).  At 
the  end  of  one  or  two  days,  wash  the  preparations  under  the  water  tap  for  one 
hour,  and  then  harden  in  20  c.cm.  of  alcohol  of  gradually  increasing  strengths 
(p.  267).     Colour  thin  sections  with  safiVanin,  and  mount  in  dammar. 

6.  Elements  of  testis.  Method  No.  6,  p.  218.  Place  a  portion,  1  c.cm.  in 
size,  of  fresh  testis  of  ox  in  20  c.cm.  of  Ranvier's  alcohol  (p.  260),  and  at  the  end 
of  five  hours  teaze  out  in  a  drop  of  the  alcohol.  Colour  while  under  the  cover- 
glass  (p.  277)  with  picrocarmine  (p.  262),  and  preserve  in  diluted  glycerine. 

(a)  To  see  liriiKj  spermatozoids,  place  on  a  clean  slide  a  drop  of  the  milky  fluid 
issuing  from  the  cut  surface  of  a  fresh  testis,  add  a  drop  of  salt  solution  (p.  260),  put 
on  a  cover-glass,  and  examine  with  a  high  power.  After  a  little  time,  allow  a 
drop  of  distilled  water  to  pass  under  the  cover-glass  (p.  277),  and  the  movements 
of  the  spermatozoids  will  cease.  Observe  the  different  forms,  oval  or  round,  of 
the  head.  Immature  spermatozoids  carry  a  little  behind  the  head  small  bits  of 
protoplasm.  To  preserve  spermatozoids,  allow  semen  diluted  with  water  to  dry 
on  a  slide,  place  a  cover-glass  on  it,  and  fix  with  cement. 

(6)  To  detect  semen  staiius  on  linen,  cut  a  bit  of  the  stained  portion,  5  to  10  mm. 
broad,  moisten  in  a  watch-glass  with  distilled  water,  for  from  five  to  ten  minutes, 
and  then  teaze  out  a  small  portion.  Then  mount  the  teazed  fragment  in  water, 
put  on  cover-glass,  and  examine  with  a  magnifying  power  of  500  diameters. 
Examine  the  edges  of  the  linen  fibres,  as  the  spermatozoids  adhere  to  these. 
Sometimes  the  heads  of  the  spermatozoids  break  off.  The  isolated  heads  may  be 
recognized  by  their  peculiar  brilliancy,  and  in  the  semen  of  man,  by  their  very 
small  size,  about  4  )x,  or  the  -g-g'-u-ij  of  an  inch. 

(c)  Spermatozoids  of  the  frog.  The  male  frog  is  recognized  by  well-developed 
warts  on  the  fore  feet.  Kill  the  animal ;  open  the  abdomen.  The  testes  are  two 
small  kidney-shaped  bodies  which  lie  at  the  sides  of  the  vertebral  column.  Cut 
one  testicle  by  a  transverse  incision,  squeeze  out  a  drop  of  fluid  on  a  slide,  dilute 
with  a  drop  of  salt  solution  (p.  260),  put  on  cover-glass,  and  examine.  The  sper- 
matozoids are  then  seen  to  have  very  long  slender  heads,  and  the  tails  so  thin  as 
almost  to  escape  notice.     Immature  spermatozoids  lie  in  clusters. 

7.  Ovary,  Method  No.  7,  p.  220.  Ovaries  of  small  animals  ai'e  to  be  fixed  as  a 
whole.  The  ovary  of  one  of  the  higher  animals,  or  of  a  woman,  should  have  a 
number  of  transverse  and  longitudinal  cuts  made  in  it  before  throwing  it  into  from 
100  to  200  c.cm.  of  Kleinenberg's  sulpho-picric  acid  (p.  261).  It  is  afterwards 
hardened  in  100  c.cm.  of  alcohol  of  gradually  increasing  strength  (p.  267).  Ova 
often  fall  out  of  the  larger  Graafian  vesicles,  and  many  sections  may  have  to  be 
made  to  secure  a  good  specimen.  Colour  with  h.-ematoxylin  (p.  262)  or  with  borax 
carmine  (p.  262),  and  mount  in  dammar. 

8.  Ovary,  Method  No.  8,  p.  221.     See  Method  No.  7. 

9.  Ovary,  Method  No.  9,  p.  222.     See  Method  No.  7. 

10.  Ovary,  Method  No.  10,  p.  223.     See  Method  No.  7. 

(a.)  Fresh  ova.  Obtain  the  fresh  ovaries  of  a  cow  from  the  slaughter  house. 
The  large  Graafian  vesicles  are  about  the  size  of  a  pea.     Cut  one  or  more  out  of 


METHODS  OF  MAKING  HISTOLOGICAL  PREPARATIONS.    489 

the  ovary  by  means  of  scissors.  Lay  the  isolated  vesicle  on  a  slide,  and  prick  it 
with  a  needle,  making  the  puncture  as  near  the  slide  as  possible.  The  liquor 
folliculi  flows  out,  and  among  cells  of  the  cumulus  ovigerus,  the  ovum  must  be 
sought  for  with  the  aid  of  a  magnifying  glass.  On  finding  it,  place  it  in  the 
middle  of  a  slide  in  a  drop  of  salt  solution,  surround  it  with  a  little  ring  of  paper, 
and  then  lay  the  cover-glass  gently  on,  so  as  to  avoid  pressure.  This  is  an  opera- 
tion much  easier  to  describe  than  to  perform. 

(6)  Ova  of  frog.  Lay  on  a  slide  a  bit  of  fresh  ovary  of  a  frog,  and  puncture 
all  the  black  ova,  so  that  the  contents  flow  oiit.  Place  the  remainder  in  a  watch- 
glass,  in  distilled  water,  and  wash  by  moving  the  contents  to  and  fro  with  needles. 
Place  the  watch-glass  on  a  black  background,  so  as  to  see  distinctly  the  unpig- 
mented  follicles.  Remove  a  bit  of  the  unpigmented  portion  to  a  slide,  cover  with 
a,  drop  of  salt  solution,  put  on  a  cover-glass,  and  examine.  Such  ova  have  a  very 
large  germinal  vesicle,  the  germinal  spot  disappears  early,  and  usually  cannot  be 
seen.  The  dark  patch  seen  is  the  yolk  nucleus.  Often  on  the  circumference  of 
the  ovum  a  delicately  striated  membrane  may  be  seen.  This  is  the  theca  folliculi 
with  a  single  layer  of  epithelial  cells. 

11.  Leucocytes,  Method  No.  11,  p.  295.  Clean  a  slide  and  cover-glass  carefully 
with  alcohol.  Place  on  the  slide  a  small  drop  of  frog's  blood,  lay  on  the  cover- 
glass,  and  fix  it  with  a  layer  of  paraffin  (p.  277).  Coloured  and  colourless  cor- 
puscles are  seen.  Examine  the  more  granular  colourless  corpuscles  carefully  with 
high  power.  The  movements  occur  slowly,  and  the  most  effective  way  of  being 
convinced  that  they  do  occur  is  to  make  drawings  of  the  same  leucocyte  at 
intervals  of  one  or  two  minutes. 

12.  Secreting  Epithelial  Cells,  Method  No.  12,  p.  297.  To  see  the  changes 
connected  with  secretion,  use  the  stomach  of  a  dog  or  cat  that  has  received  no 
food  for  a  day  or  so.  The  stomach  of  the  rabbit  is  not  suitable,  as  the  chief  cells 
are  small.  Portions  of  mucous  membrane,  1  cm.  broad,  are  placed  in  10  c.cm.  of 
absolute  alcohol,  and  the  alcohol  is  changed  in  half  an  hour.  Then  examine. 
The  human  stomach,  if  obtained  soon  after  death,  shows  the  gland  structure  even 
better  than  that  of  the  dog  or  cat,  as  the  gland  tubes  are  wider  apart.  Cut  very 
thin  sections.     For  further  details,  see  Stomach,  Vol.  II. 

13.  Blood  Corpuscles,  Method  No.  13,  p.  300.  Carefully  clean  with  alcohol  a 
slide  and  a  small  cover-glass.  Then  puncture  with  a  clean  needle  the  tip  of  the  finger. 
The  drop  of  blood  first  coming  to  the  surface  is  wiped  away  and  the  second  drop  is 
caught  on  the  cover-glass  and  the  cover-glass  is  placed  on  the  slide.  Seal  up  the 
preparation  with  a  little  paraffin.  Examine  with  high  power,  observe  rouleaux 
and  coloured  and  colourless  blood  corpuscles.  The  jagged  edges  of  many  corpuscles 
are  produced  by  evaporation.  After  removing  the  paraffin  from  the  rim  of 
the  cover-glass  on  the  one  side,  place  a  drop  of  water  on  the  edge  of  the  cover- 
glass,  thus  discolouration  of  the  blood  corpuscles  is  noticed,  while  the  water  be- 
comes yellowish,  the  blood  corpuscles  also  become  globular,  and  they  appear  as 
pale  spheres  which  disappear  entirely  at  the  close  of  the  experiment.  Then  study 
carefully  one  corpuscle. 

[a)  Small  blood  plates  or  plaques  are  obtained  if,  previous  to  the  puncture  of 
the  finger,  we  lay  on  the  tip  a  drop  of  a  filtered  mixture  of  5  drops  of  an 
aqueous  solution  of  methyl  violet  (p.  263)  along  with  5  c.  cm.  of  a  solution  of  common 
salt  (p.  260),  and  then  prick  the  finger  through  the  drop.  The  blood  issuing  out 
of  it  mixes  with  the  methyl  violet ;  a  drop  is  laid  on  the  under  surface  of  the 
cover-glass  and  examined  with  high  powers.     The  plaques  are  coloured  intensely 


490  APPENDIX  1. 

blue,  of  peculiar  brilliancy,  disc-shaped,  and  not  to  be  confounded  with  the  white 
corpuscles  likewise  coloured.  Their  quantity  varies  in  individual  cases.  Avoid 
confounding  the  blood  plaques  with  gi-anulated  impurities  which  may  be  even  in 
the  filtered  colour  solution. 

{}))  Coloured  blood  corpuscles  of  animals  (frog,  etc.)  should  be  taken  from  the 
newly-killed  animal  and  treated  according  to  Method  No.  13. 

(o)  Blood  stains.  Moisten  small  portions  of  the  stain  in  35  per  cent,  solution  of 
caustic  potash  on  the  slide,  teaze  small  portions  of  blood-stained  linen  in  a  drop  of  the 
caustic  potash.  Although  the  coloured  blood  corpuscles  of  our  domestic  mammalia 
are  smaller  than  those  of  man,  it  is  nevertheless  impossible  to  decide,  from  the 
size  of  the  blood  corpuscles,  the  question  whether  the  blood  originally  belonged  to 
man  or  to  some  other  mammal.  It  is,  on  the  other  hand,  easy  to  distinguish  the 
oval  blood  corpuscles  of  the  other  vertebrates  from  disc-shaped  ones  of  the 
mammalia. 

{d)  Blood  crystals  (pp.  119  and  129).  (a)  The  production  of  the  hs'min  crystals 
is  easy  (p.  129,  Fig.  53).  Cut  a  small  flap,  3  mm.  broad,  of  blood-soaked,  diy 
linen,  and  place  it  along  with  a  morsel  of  common  salt,  the  size  of  a  pin's  head,  on 
a  clean  slide.  Add  a  large  drop  of  glacial  acetic  acid  and  pound,  with  a  blunt 
glass  rod,  the  salt  and  the  linen  until  such  time  as  the  acetic  acid  assumes  a 
brownish  hue.  Do  this  rapidly  otherwise  the  acetic  acid  evaporates.  Then  gently 
heat  the  slide  over  the  flame  until  the  fluid  boils  up  07ice.  The  small  bit  of  linen 
is  now  removed  and  the  dry  brown  spaces  investigated  on  the  slide  with  high 
powers.  We  occasionally  perceive,  even  without  a  cover-glass  and  without  any 
preserving  fluid,  hroirn  crystals  of  hsemin  near  numerous  fragments  of  white 
crystals  of  common  salt.  For  preservation  cover  the  slide  at  once  with  a  larg  e 
drop  of  dammar  varnish  and  a  cover-glass.  The  form  and  size  of  the  ha?min 
crystals  vary.  We  may  obtain  from  the  same  blood  complete  crystals,  partly 
isolated,  partly  lying  crosswise  under  each  other,  partly  united  into  stars,  along 
with  forms  resembling  that  of  a  whetstone,  and  the  smallest  particles  may  scarcely 
exhibit  the  crystal  form.  The  discovery  of  hsemin  crystals  is  of  great  importance 
for  medico-legal  pui'poses.  It  is  often  thus  possible  to  discover  the  crystals  on 
portions  of  clothing,  but  it  is  often  difficult  to  furnish  proof  from  small  stains, 
especially  on  rusty  iron,  that  they  have  their  origin  in  blood.  The  instruments- 
and  reagents  to  be  employed  in  such  investigations  must  be  absolutely  clean. 

(e)  Hitmatoidin  crystals  (Fig.  52,  p.  129)  are  found  by  teazing  out  old  extravasa- 
tions of  blood,  which  to  the  naked  eye  are  recognized  by  their  rusty-brown  colour. 
Hffimatoidin  crystals  occur  in  apoplectic  cysts,  in  a  corpus  luteum,  etc. 

(/)  Hamoglohin  crystals  (Fig.  48,  p.  119)  are  produced  from  human  blood  (best 
from  the  splenic  vein)  only  with  difBculty.  We  sometimes  obtain  them  if  we  con- 
vey a  drop  of  the  blood  of  the  vein  of  the  spleen  to  the  slide,  and  after  five  minutes 
add  a  drop  of  water,  cover  the  whole  with  a  cover-glass  and  allow  it  to  stand  in 
the  light.  After  some  time  the  crystals  may  appear  on  the  margin  of  the  pre- 
paration. 

14.  Epithelial  Cells,  Method  No.  14,  p.  301.  Scrape  ofi"from  the  upper  surface 
of  the  tip  of  the  tongue  a  little  mucus  and  place  it  on  a  slide  with  a  drop  of  salt 
solution  (p.  260),  then  put  on  a  cover-glass.  Then  observe  the  flat  squamous  epi- 
thelium (Fig.  147,  1,  p.  301)  and  the  salivary  corpuscles  (Fig.  143,  h,  p.  296). 
Sometimes  also  one  may  find  a  dark  mass  of  fungus  threads  [Leptolhrix  huccalis). 
Stain  under  cover-glass  with  picrocarmine  (p.  277),  and  after  adding  a  little 
glycerine  the  preparation  may  be  kept. 


METHODS  OF  MAKING  HISTOLOGICAL  PREPARATIONS.    491 

15.  Bristle  Cells,  Method  No.  15,  p.  302.  Cut  from  the  bill  of  a  newly-killed 
duck  or  goose  the  yellowish  skin  passing  over  the  margin  of  the  mandible  and 
place  small  portions,  1  to  2  mm.  thick  and  1  cm.  long,  into  3  c.cm.  of  a  two  per 
cent.  solution  of  osmic  acid  along  with  3  c.cm.  of  distilled  water.  Leave  this  for 
twenty-four  hours  in  the  dark.  Then  wash  small  portions  for  one  hour  under  the 
tap  and  transfer  to  20  c.cm.  of  90  per  cent,  alcohol.  After  six  hours  cut  vertical 
sections,  mount  in  dammar.  Such  preparations  are  better  unstained.  (See  Touch, 
Vol.  II.) 

16.  Pigment  Epithrlixtm  of  Retina,  Method  No.  16,  p.  302.  Open  eyeball  of 
sheep  or  ox  in  water,  allow  retina  to  float  off,  and  on  the  surface  of  the  choroid 
behind  it  the  cells  will  be  found.  The  light  spots  in  the  cells  are  nuclei.  They 
are  not  readily  preserved,  but  sometimes  they  keep  well  in  a  drop  of  glycerine. 

17.  Simple  Cylindrical  Epithelium,  Method  No,  17,  p.  302.  See  Method 
No.  12. 

18.  Stratified  Pavement  Epithelium,  Method  No.  18,  p.  303.  Remove 
from  the  dead  body  of  a  cat  the  larynx,  trachea,  etc.  Place  the  preparation  for  a. 
period  of  from  two  to  six  weeks  in  from  200  to  400  c.cm.  of  Miiller's  fluid  (p.  261), 
wash  under  water  tap  for  one  hour,  harden  in  200  c.cm.  alcohol  of  increasing 
strengths  (p.  267).  At  the  end  of  eight  days  cut  transverse  and  longiti;dinal  sec- 
tions, through  vocal  cords,  through  trachea,  and  through  the  thyroid  gland ;  stain 
for  five  minutes  in  hsematoxylin  (p.  262),  and  mount  in  dammar. 

19.  Stratified  Ciliated  Epithelium,  Method  No.  19,  p.  304.  Found  in  regio 
respiratoria  of  nose.  Cut  small  portions,  5  to  10  c.  cm.  broad,  from  lower  portion  of 
septum  narimn,  fix  and  harden  in  20  c.cm.  of  absolute  alcohol.  For  fine  sections, 
use  nasal  mucous  membrane  from  rabbit.  Stain  with  haematoxylin  (p.  262)  and 
mount  in  dammar. 

Ciliary  motion,  p.  321.  Kill  a  frog,  lay  it  on  its  back,  and  remove  lower  jaw, 
by  using  scissors  ;  the  roof  of  the  mouth  is  thus  exposed.  Cut  from  the  roof  of 
the  mouth  a  small  strip  of  membrane,  5  mm.  long,  and  place  it  in  a  few  drops  of 
solution  of  common  salt  (p.  260)  on  a  slide,  and  cover  with  a  cover-glass.  With 
a  low  power  a  beginner  can  scarcely  perceive  anything,  unless  cun-ents,  in 
which  large  blood  corpuscles  swim,  direct  him  to  the  right  spot.  Put  on, 
therefore,  the  high  power  and  search  the  margins  of  the  preparation.  At  first  the 
motion  of  the  cilia  is  still  so  lively  that  the  observer  is  unable  to  distinguish  indi- 
vidual cilia,  the  entire  ciliary  margin  shows  a  wavy  motion  like  that  of  a  coriifiehl 
moved  by  the  wind.  After  a  few  minutes  this  rapid  motion  abates  and  the  cilia 
become  visible.  If  the  motion  is  stopped  it  may  be  started  anew  by  leading: 
through  one  drop  of  concentrated  caustic  potash ;  the  efi'ect  is,  however,  short- 
lived, so  that  the  eye  of  the  observer  must  not,  during  the  process  of  leading 
through,  leave  the  ocular.  The  addition  of  water  immediately  arrests  the  ciliary 
movement. 

20.  Fat  Cells,  Method  No.  20,  p.  305.  Take  from  the  axilla  of  a  human 
subject  a  small  fragment  of  the  reddish  yellow  gelatinous  fat,  teaze  out  with 
needles  on  a  dry  slide,  quickly  add  a  drop  of  salt  solution  (p.  260),  and  put  on  a 
cover-glass.  Thin  places  show  fat  cells.  Colour  under  cover-glass  (p.  277)  with 
picrocarmine  (p.  262),  and  mount  in  dilute  glycerine.  Always  examine  fat  cells 
in  a  solution  of  common  salt. 

21.  Involuntary  Muscle,  Method  No.  21,  p.  306.  Place  a  small  bit  of 
stomach  or  intestine  of  newly  killed  frog  into  20  c.cm.  of  caustic  potash  and 
treat  as  in  Method  No.  22  h. 


492  APPENDIX  I. 

22.  Striated  Muscle,  Method  No.  22,  p.  307.  (ti)  Trmisvemely  striated  mmcle 
fibres  of  the  frog. — Cut  with  the  scissors  in  the  direction  of  the  course  of  the 
■fibres  a  strip  of  muscle  1  cm.  long  out  of  the  adductors  of  a  newly  killed  frog ; 
teaze  a  small  part,  taken  from  the  inner  surface  of  the  strip,  in  a  drop  of  salt 
solution  (p.  260)  ;  then  add  a  second  larger  drop  of  the  same  fluid,  and  lay  on  a 
•cover-glass  without  pressure  ;  with  a  low  power  (50  d. )  observe  the  cylindrical 
shape,  the  various  thickness,  occasionally  even  the  transverse  striation  of  the 
isolated  muscle  fibres  ;  with  high  powers  (240  d.)  notice  the  distinct  transverse 
striation,  sometimes  pale  nuclei  and  glittering  granules.  Very  numerous  granules 
in  muscle  fibres  are  pathological.  In  cases  in  which  the  muscle  fibres  are  cut 
transversely,  we  may  perceive  the  muscle  substance  squeezed  out  of  the  tube  of 
"the  sarcolemnia.  {h)  Of  man. — Beautiful  transverse  striation  is  seen  on  human 
muscles  taken  from  a  fresh  subject.  For  preservation,  colour  under  the  cover- 
glass  (p.  277)  with  picrocarmine  (p.  262),  and  after  complete  colouring,  in  five 
minutes,  introduce  diluted  glycerine,  and  seal  up.  (c)  Sarcole.mma. — Allow  a 
couple  of  drops  of  water  to  flow  on  preparation  for  Method  No.  25  a.  After  two 
to  five  minutes,  observe  with  low  power  (50  d.)  how  the  sarcolemma  is  raised  up 
in  the  form  of  transparent  vesicles  ;  in  other  places,  where  the  torn  muscle 
substance  has  contracted,  the  sarcolemma  appears  as  a  fine  striation.  [d)  Nuclei. — 
Take  a  bit  of  preparation  for  Method  No.  25  a,  and  allow  a  drop  of  acetic  acid  to 
flow  on  it.  Even  with  low  powers  the  shrivelled  or  sharply  outlined  nuclei 
•appear  as  dark  or  spindle-shaped  lines,  (e)  Fibrils. — Place  a  fresh  muscle  of  a 
frog  in  20  c. cm.  of  chromic  acid  "l  per  cent.  (p.  261).  After  twenty-four  hours, 
teaze  in  a  drop  of  water,  and  thus  obtain  fibres  whose  ends  split  up  into  fibrils. 
If  a  permanent  preparation  is  desiderated,  place  the  muscle  in  water  for  one 
hour,  then  into  20  c.  cm.  of  33  per  cent,  alcohol  for  ten  to  twenty  hours  ;  or  pre- 
serve it  in  70  per  cent,  alcohol.  If  the  chromic  acid  is  exhausted,  protracted 
immersion  for  several  weeks  in  alcohol  frequently  changed  will  suit.  Allow 
picrocarmine  to  act  on  the  preparation,  and,  after  complete  colouration,  replace  it 
by  dilute  glycerine.  (/)  Terminations  of  the  muscle  fibres. — Place  the  fresh  gastroc- 
nemius of  a  frog  in  20  c.cm.  of  concentrated  caustic  potash.  After  thirty  to 
sixty  minutes  the  muscle  disintegrates  on  its  fibres  being  pressed  slightly  with 
a  glass  rod.  If  this  does  not  occur,  the  potash  has  been  too  weak.  Transfer  a 
number  of  fibres  into  a  drop  of  the  same  potash  on  the  slide  (the  fibres  cannot  be 
investigated  in  water  or  glycerine,  for  the  caustic  potash  thus  diluted  immediately 
destroys  the  fibres),  and  cover  cautiously  with  a  cover-glass.  With  low  powers, 
we  perceive  the  terminations  of  the  muscle  fibres  and  numerous  glittering  nuclei, 
some  of  which  may  be  vesicular. 

23.  Ramified  Muscular  Fibres,  Method  No.  23,  p.  307.  Cut  out  the  tongue 
from  a  newly  killed  frog  and  place  it  in  20  c.cm.  of  pure  nitric  acid,  to  which 
5  grm.  of  chloride  of  potassium  are  added.  Undissolved  KCl  must  still  remain  at 
the  bottom  of  the  vessel.  After  fifteen  hours,  raise  cautiously  with  glass  rods  the 
tongue  out  of  the  water,  and  place  it  in  .30  c.cm.  of  distilled  water,  which  is  to 
be  often  changed.  The  tongue  may  continue  in  this  up  to  eight  days,  but  it  may 
be  operated  upon  after  twenty-four  hours.  Place  it  in  a  small  test-tube  half 
filled  with  water,  and  shake  it  for  a  few  minutes  ;  thereupon  the  tongue  disinte- 
grates. Now  pour  the  whole  into  a  small  dish,  and,  after  one  hour  or  later,  place 
a  little  of  the  precipitate  formed  in  a  drop  of  water  on  to  a  slide.  Teaze  with 
needles  so  as  to  isolate  fibres.  Stain  with  picrocarmine  under  the  cover-glass 
and  preserve  in  dilute  glycerine. 


METHODS  OF  MAKING  HISTOLOGICAL  PREPARATIONS.    493 

24.  Striated  Mpscle,  Method  No.  24,  p.  311.     See  Method  No.  22  e. 

25.  Isolated  Muscle  Fibres,  Method  No.  25,  p.  313.     See  Method  No.  22/. 

26.  MrscLE  Fibre  of  Heart,  Method  No.  26,  p.  313.  Cut  out  a  papillary 
muscle  from  human  heart,  and  place  in  40  c.cm.  of  absolute  alcohol.  After  from 
twenty -four  to  forty-eight  hours,  it  is  suflBciently  hard  for  cutting.  Stain  with 
hsematoxylin  (p.  262),  and  mount  in  glycerine. 

27.  Gaxglio>-ic  Nerve  Cells,  Method  No.  27,  p.  314.  Teaze  out  a  small 
portion  of  the  gasserian  ganglion  of  a  sheep  in  a  drop  of  salt  solution,  and  colour 
with  picrocarraine  (p.  262). 

28.  Nerve  Cells,  Method  No.  28,  p.  314.  Take  some  grey  matter  from  the 
fresh  spinal  cord  of  an  ox  and  place  a  portion,  1  to  2  cm.  long,  in  50  c.cm.  of  very 
dilute  soliition  of  chromic  acid  (5  c.cm.  of  "5  per  cent,  solution  in  45  c.cm.  of  dis- 
tilled water).  After  changing  the  fluid  often  during  from  three  to  eight  days,  the 
grey  matter  will  be  found  to  be  macerated  to  a  soft  pulp.  Transfer  this  carefully 
with  a  spatula  into  the  undiluted  carmine  solution  (p.  262),  and  leave  it  there  for 
from  twelve  to  twenty  hours.  Then  transfer  into  50  c.cm.  of  distilled  water,  so- 
as  to  wash  out  part  of  the  colour,  and,  after  five  minutes,  spread  it  out  in  a  thin 
layer  on  a  dry  slide.  The  multipolar  nerve  cells  will  then  be  seen,  but  the  pro- 
cesses are  not  visible.  Allow  the  layer  to  dry,  cover  with  dammar,  and  place  a. 
cover-glass  gently  over  it. 

29.  Nerve  Cells  oe  Cerebrum  akd  Cerebellum,  Method  No.  29,  p.  314.. 
Same  process  as  detailed  in  Method  No.  28. 

30.  Medullated  Nerve  Fibres,  Method  No.  30,  p.  315.  Remove  the  sciatic^ 
nerve  of  a  newly  killed  frog,  cutting  out  a  portion  about  1  cm.  in  length.  Teaze 
a  small  bit  in  a  drop  of  a  solution  of  common  salt.  It  is  better  to  teaze  on  a  dry 
slide.  Apply  the  needle  to  the  lower  end  of  the  nerve,  so  as  to  pull  asunder 
the  fibrils  for  about  half  their  length,  with  a  drop  of  salt  solution  and  a  cover- 
glass.  The  thin  film  of  nerve  matter  contains  numerous  isolated  nerve  fibres.  Do- 
this  very  quickly  (say  in  fifteen  seconds),  so  that  the  nerA^e  fibres  do  not  dry. 

31.  Changes  of  the  Maerow  Sheath,  Method  No.  31,  p.  315.  Let  a  drop  of 
water  flow  from  the  rim  of  the  cover-glass  into  the  preparation.  Even  in  one* 
minute,  the  changes  shown  in  Fig.  176,  4,  p.  315,  may  be  observed. 

32.  Axis  Cylinder,  Method  No.  32,  p.  315.  Teaze  when  dry  (as  in  No.  30),. 
and,  instead  of  a  solution  of  common  salt,  add  a  drop  of  absolute  alcohol.  The 
discovery  of  the  axis  cylinder  requires  practice.     (See  Fig.  176,  5,  p.  315.) 

33.  Nerve  of  Rabbit,  Method  No.  33,  p.  315.  Remove  the  sciatic  nerve  of  » 
newly  killed  rabbit,  by  the  following  process,  without  touching  it  with  the  fingers. 
Push  a  long  splinter  of  wood  below  the  nerve  and  tie  the  nerve  to  the  ends  of 
the  splinter  above  and  below.  Then  divide  the  nerve  and  lift  out  the  splinter 
with  the  nerve  attached,  and  place  it  in  100  c.cm.  of  a  1  per  cent,  solution  of 
chromic  acid.  Axis  Cylinder.  After  twenty-four  hours,  the  ligatures  are  cut 
through  ;  a  small  portion  of  nerve,  "5  to  1  cm.  long,  is  cut  off,  and  teazed  into  fine 
bundles,  not  into  fibrils.  The  bundles  separate  in  the  solution  of  chromic  acid. 
After  twenty -four  hours  more,  they  are  transferred  into  50  c.cm.  of  distilled 
water ;  and,  after  two  to  tliree  hours,  they  are  hardened  in  alcohol  of  increasing- 
strengths  (p.  267).  It  is  well  to  leave  the  btmdles  a  longer  time,  say  from  one  to 
eight  weeks,  in  90  per  cent,  alcohol,  because  they  then  stain  easily.  After  com- 
plete hardening,  the  bundles  are  minutely  teazed  in  a  drop  of  picrocarmine,  and 
after  completed  colouration,  which  invariably,  after  the  duration  of  the  preceding 
hardening  in  alcohol,  takes  place  in  from  half  a  day  to  three  days.      Preserve  in 


494  APPENDIX  J. 

?ici<liilatccl  glycerine.  Tlie  nodes  are  not  so  distinct  as  in  fresh  preparations  or  in 
tliat  of  osmic  acid,  bat  are  to  be  recognized  as  tine  ti'ansverse  lines.  The  some- 
what shrivelled  axis  cylinder  and  nuclei  are  coloured  red.  The  axis  cylinder  not 
Tinfrequently  moves  out  of  its  place,  so  that  the  biconical  excrescence  does  not  any 
longer  lie  on  the  constrictions,  but  above  or  beneath  them. 

34.  NiTR.\TE  OF  Silver  on  Nerves,  Method  No.  34,  p.  316.  Make  the  following — 
Mix  10  c.cm.  of  1  per  cent,  solution  of  nitrate  of  silver  with  20  c.cm  of  distilled 
water.  Kill  a  frog,  open  the  abdouiinal  cavity,  remove  the  entrails,  so  as  to 
expose  the  nerves  lying  on  the  side  of  the  vertebral  column.  Rinse  out  the 
abdominal  cavity  by  pouring  distilled  water  over  it,  and,  after  the  water  has  run 
oif,  pour  about  one  third  of  the  solution  of  nitrate  of  silver  upon  the  nerves.  After 
two  minutes,  cut  out  the  delicate  nerves  carefullj^  and  place  them  for  half  an 
hour  in  the  remainder  of  the  nitrate  of  silver  solution.  Transfer  them  into  10 
c.cm.  of  distilled  water,  in  which  they  may  lie  from  one  to  twenty-four  hours.  If 
we  then  examine  the  nerve  in  a  drop  of  water,  we  recognize  with  low  powers  the 
-endothelial  sheath  (Henle'ii  sheath),  and  numerous  pigment  cells.  A  blood-vessel 
often  lies  near  the  nerve.  Teaze  a  bit  of  the  nerve,  cover  it  with  a  cover-glass, 
and  place  on  the  margin  of  the  cover-glass  a  small  drop  of  dilute  glycerine.  If  we 
now  examine  with  high  powers,  we  will  notice  little  coloured  constrictions  and 
axis-cylindei's.  Allow  the  preparation  to  lie  a  few  hours  exposed  to  daylight  (only 
a  few  minutes  in  sunlight),  and  the  blackening  of  the  parts  becomes  more  marked. 
It  is  at  tirst  difficult  for  the  beginner  to  recognize  the  swellings  on  the  nerve,  which, 
on  account  of  teazing,  are  often  widely  separated  from  the  constrictions.  After  a 
little  practice,  the  forms  are  easily  observed. 

35.  Non-Medullated  Nerve  Fibres,  Method  No.  35,  p.  316.  The  vagus  nerve 
of  a  rabbit  is  teazed  when  dry,  then  covered  with  a  few  drops  of  a  1  per  cent, 
solution  of  osmic  acid.  After  five  to  ten  minutes,  the  meduUated  nerves  are 
blackened.  Now,  let  the  osmic  acid  solution  run  off,  and  add  a  few  drops  of  dis- 
tilled water  ;  the  water  is  renewed  after  five  minutes.  After  other  five  minutes, 
pour  the  water  off,  add  a  few  drops  of  picrocarmine  to  the  preparation,  cover  it 
with  a  cover-glass,  and  leave  it  from  twenty-four  to  forty-eight  hours  in  a  moist 
■chamber,  then  replace  the  picrocarmine  by  acidulated  glycerine.  With  high 
powers  we  perceive  the  medullated  nerve  fibres  delicately  striated  longitudinally. 
They  show  a  blue-black  hue.  The  non-meduUated  fibres  are  similarly  striated, 
ibut  show  a  pale  grey  tint.  The  pale  nerve  fibres  not  infrequently  appear  to  run 
parallel  for  a  long  distance.  Similar  treatment  of  the  sympathetic  nerve  yields 
more  numerous  non-medullated  nerve  fibres,  only  this  nerve  is  more  difficult  to 
■discover.  Cut  through  the  great  cornua  of  the  hyoid  bone,  then  the  nerve  and  the 
hypoglossus  nerve  will  be  seen.  Behind  the  vagus  the  sj^mpathetic  lies,  and  it  is 
recognized  by  the  large,  oval,  yellowish-translucent  ganglion,  the  superior  cervical 
ganglion.  Teaze  out  a  bit  of  the  firm  part  of  the  nerve  below  the  ganglion.  The 
preparation  will  also  show  double-nucleated  ganglion  cells,  but  it  is  very  difficult 
to  isolate  the  cells  so  as  to  show  their  processes  or  poles. 

36.  Connective  Tissue,  Alethod  No.  36,  p.  323.  Connective  tissue  bundles. 
Intermuscular  connective  tissue.  The  thin  lamina  lying  between  the  serratus 
niagnus  and  the  intercostal  muscles  is  cut  into  small  strips,  1  to  2  cm.  long.  A 
very  small  portion  is  quickly  spread  out  with  needles  on  a  dry  slide,  and  covered 
with  a  drop  of  salt  solution  and  with  a  cover-glass.  We  observe  the  bundles  of 
-connective  tissue  pale  and  undulating. 

37.  Fine  Elastic  Tissue,  Method  No.  37,  p.   323.     To  the  last  preparation 


METHODS  OF  MAKING  HISTOLOGICAL  PREPARATIONS.    495 

(Method  No.  36)  add  a  few  drops  of  acetic  acid.  The  bundles  of  connective  tissue 
swell  and  become  gelatinous,  and  the  elastic  fibres  remain  unaltered,  and  appear 
as  sharply-defined  dark  culling  fibres. 

38.  Coarse  Elastic  Tissue,  Method  No.  38,  p.  323.  Larger  elastic  fibres  are 
obtained  by  teazing  the  fibres  of  a  small  portion  (1  cm.  long,  and  of  the  thickness 
of  a  pill),  of  the  fresh  ligamentum  nuchje  of  an  ox  in  a  drop  of  salt  solution.  Stain 
with  picrocarmine,  and  preserve  in  diluted  glycerine. 

39.  Transverse  Sections  of  Coarse  Elastic  Fibres,  Method  No.  39,  p.  323, 
are  obtained  by  drying  a  piece  of  the  ligamentum  nuchfe,  10  cm.  long,  1  to  2  cm. 
thick,  and  then  treating  it  by  Method  No.  45. 

40.  Fenestrated  Membranes,  Method  No.  40,  p.  324,  are  obtained  if  we  bring 
a  small  portion,  5  mm.  broad,  of  the  endocardium  on  a  slide  in  a  drop  of  water, 
and  allow  1  to  2  drops  of  caustic  potash  to  flow  under  the  cover-glass.  Examine 
the  margins  of  the  preparation.  The  basilar  artery  also  furnishes  fenestrated 
membranes.  Cut  from  the  artery  a  portion,  1  cm.  long,  lay  it  on  to  a  slide,  open 
it  longitudinally  with  scissors,  add  a  drop  of  water,  endeavour,  by  scraping  with 
a  scalpel,  to  separate  the  wall  of  the  artery  into  lam  elite.  Place  on  it  a  cover- 
glass,  then  add  caustic  potash,  and  the  small  holes  of  the  membrane  appear  like 
glittering  nuclei. 

41.  Mucous  Connective  Tissue,  Method  No.  41,  p.  325.  Fix  for  three  to  four 
weeks  the  umbilical  cord  of  a  human  embryo  of  three  to  four  months  (or  of  the 
embryo  of  a  pig,  3  to  6  cm.  long),  in  100  c.cm.  of  Miiller's  fluid.  Then  harden  in 
30  c.cm.  of  alcohol,  strengthened  by  degi'ees.  The  cord  will  still  be  very  soft ;  to 
obtain  transverse  sections  of  it,  embed  it  in  liver,  and  on  being  cut  it  must  be 
somewhat  compressed  by  the  fingers.  Stain  the  sections  in  picrocarmine  for  two 
hours,  or  with  hsematoxylin  for  five  minutes.  Examine  in  a  drop  of  distilled 
water  ;  the  delicate  processes  of  the  cells  and  the  bundles  of  connective  tissue  are 
invisible  in  glycerine  or  dammar  varnish.  Examine  pieces  remote  from  vessels. 
The  older  the  embryo  the  greater  is  the  number  of  the  connective  tissue  bundles. 
It  may  be  preserved  in  dilute  glycerine. 

42.  Connective  Tissue,  Method  No.  42,  p.-  326.  Connective  tissue  cells  are 
made  visible  by  addition  of  a  drop  of  picrocarmine  to  preparation  No.  36  under 
the  cover-glass.  In  most  cases  we  perceive  the  nucleus  of  the  cell,  particularly 
where  the  cell  lies  on  connective  tissue  bundles.  We  may  also  perceive  the  pale 
j'ellow  variously-shaped  body  of  the  cell. 

43.  Spiral  Cells  in  Connective  Tissue,  ^Method  No  43,  p.  326.  Eemove  from 
connective  tissue  surrounding  the  vessels  of  the  cii'cle  of  Willis,  at  the  base  of  the 
brain,  a  fragment,  1  sq.  cm.  in  size,  wash  it  in  a  watch-glass  with  salt  solution, 
and  spread  it  out  with  needles  in  a  drop  of  this  solution.  Put  on  cover-glass. 
With  low  powers,  we  find  outside  of  numerous  fine  blood-vessels  the  usual  con- 
nective tissue  bundles,  but  also  more  sharply-outlined  shining  bundles,  which  are 
distinctly  higher  than  the  other  connective  tissue  bundles.  With  high  powers, 
we  can  distinguish  the  more  sharply  outlined  glittering  elastic  fibres,  and  in 
favourable  places  also  the  nuclei  of  the  connective  tissue.  Place 'such  a  bundle  in 
the  field,  and  then  add  a  few  drops  of  acetic  acid  under  the  cover-glass.  As  soon 
as  the  acid  reaches  the  bundle,  the  latter  swells,  the  fibrillar  character  disappears, 
and  there  appear  elongated  nuclei.  The  swelling  up,  however,  is  not  regular,  but 
divided  by  constrictions  into  sections  of  various  lengths.  With  weak  illumination, 
we  perceive  the  fibres  (cell  processes)  causing  the  constrictions.     To  demonstrate 


496  APPENDIX  I. 

the  cells  themselves  take  a  similar  preparation  from  a  ne-wly-born  child.     The 
manipulation  is  the  same  as  in  the  case  of  an  adult. 

4i.  Eyelid  to  show  Plasma  Cells,  Method  No.  44,  p.  326.  Fix  a  humaa 
upper  eyelid  in  100  c.cm.  of  O'o  per  cent,  solution  of  chromic  acid  for  one  to 
three  days,  and  harden,  after  two  hours'  washing  under  the  tap,  in  50  c.cm.  of 
alcohols  of  increasing  strengths.  Cut  thin  sections ;  stain  with  hematoxylin. 
This  is  difficult  with  fresh  sections,  but  succeeds  after  several  months'  hardening 
in  alcohol.     Mount  in  dammar. 

45.  Tendon,  Method  No.  45,  p.  327.  Cut  a  portion,  5  to  10  cm.  long,  of  a 
tendon,  and  let  it  dry  in  the  air  (not  in  the  sun).  Thin  tendons  (e.r/.  those  of  the 
flexor  digitalis  pedes)  are  sufficiently  dry  after  twenty-four  hours'  exposure  to  the 
temperature  of  a  room  ;  thicker  ones  require  several  days.  Next  make  with  the 
scalpel  {not  iiith  the  razor)  a  smooth  transverse  section,  and  then  cut  small  thin 
slices  from  the  tendon.  The  smallest  bits  are  thrown  into  water,  and  after  the 
lapse  of  two  minutes  stained  during  five  minutes  in  3  c.cm.  of  picrocarmine,  and 
mounted  in  dilute  glycerine.  Very  frequently  we  see  on  the  transverse  section  a 
striation  produced  by  the  mode  of  guiding  the  knife.  Place  a  second  section 
unstained  in  a  drop  of  water  on  the  slide,  and  then  allow  a  drop  of  acetic  acid  to 
flow  to  it  under  the  cover-glass.  The  marginal  parts  of  the  transverse  section 
immediately  become  much  swollen. 

Fibrils  in  tendon. — Place  a  portion  (2  cm.  long)  of  a  tendon  in  100  c.cm.  of 
saturated  watery  solution  of  picric  acid.  Next  day  tear  up  with  forceps  the 
tendon  in  the  direction  of  its  length  ;  take  out  from  the  interior  a  bundle  5  mm. 
long,  and  pull  it  asunder  on  a  dry  slide  ;  cover  it  with  a  drop  of  distilled  water, 
lay  on  a  cover  glass,  and  examine  with  a  high  power.  The  fibrils  appear  most 
delicate,  pale,  minute. 

46.  Tendon,  Method  No.  46,  p.  327.  In  order  to  study  the  more  delicate  tissue 
of  the  tendon,  the  cells,  and  their  processes,  place  portions  of  a  fresh  thin 
tendon  (e.g.  of  palmaris  longus),  3  cm.  long,  in  200  c.cm.  of  -5  per  cent,  solution 
of  chromic  acid  for  at  least  four  weeks,  changing  the  chromic  acid  solution 
frequently.  The  portions  are  then  washed  from  one  to  two  hours  under  the  tap, 
and  hardened  in  40  c.cm.  of  alcohols  of  increasing  strengths.  Transverse  sections 
are  cut  with  a  very  sharp  knife,  for  tendons  are  often  friable,  and  tend  to 
exfoliate.  The  sections  must  not  be  too  thin.  Mount  uncoloured  in  dilute 
glycerine.  Even  low  powers  show  delicate  forms  well  seen  when  light  falls 
obliquely  on  them  (see  Fig.  184,  p.  327,  B).  The  black  jagged  hollow  cavities  (z) 
enclose  tendon  cells. 

47.  Lymphoid  or  Adenoid  Tissue,  Method  No.  47,  p.  327.  Human  lymphatic 
glands  are  with  difficulty  recognizable,  as  the  entire  cortex  is  a  mass  of  tissue 
hanging  together,  in  which  lymphoid  tissue  is  irregularly  dispersed.  By  shaking, 
the  lymph  sinuses  of  the  gland  come  indistinctly  into  view,  the  protoplasmic 
matter  falls  out,  and  what  remains  appears  at  this  stage  as  I'ound  gaps.  On  the 
other  hand,  the  mesenteric  glands  are  well  adapted  for  showing  the  network  of 
trahecidce.  Place  portions  of  it,  2  cm.  long,  into  200  c.cm.  of  concentrated 
aqueous  solution  of  picric  acid,  and,  after  twenty-four  hours,  make  delicate 
sections  with  a  sharp  knife,  moistened  with  water.  This  plan  may  not  succeed  so 
well  as  after  fixation  with  alcohol,  but  thick  sections  are  useful.  The  sections 
are,  after  one  hour,  placed  in  100  c.cm.  of  distilled  water,  frequently  changed, 
and  then  stained  with  hsematoxylin  and  eosiu.  Mount  in  dammar.  The  tra- 
beculse  are  red  ;    the  lymphoid  tissue  blue.     The  leucocytes,  formerly  found  in 


METHODS  OF  MAKING  HISTOLOGICAL  PREPARATIONS.    497 

the  meshes,  are  loosened  by  the  picric  acid  treatment,  and  they  may  be  almost 
removed  by  shaking. 

48.  Hyaline  Cartilage,  Method  No.  48,  p.  329.  Cut  out  with  scissors  the 
thin  ensiform  cartilage  of  a  frog,  lay  it  on  a  dry  slide,  cover  it  with  a  cover-glass, 
and  investigate  quickly  with  high  powei'S.  The  cartilage  cells  completely  fill  up 
the  cartilage  spaces.     For  longer  observation,  add  a  drop  of  salt  solution. 

49.  Hyaline  Cartilage  of  Ribs,  Method  No.  49,  p.  329.  Without  further 
preparation,  make  fine  sections  with  a  dry  razor  ;  place  these  in  a  drop  of  water 
under  a  cover-glass.  Find  glittering  places  in  the  cartilage.  These  contain  solid 
fibres,  due  to  calcification.     Preserve  in  glycerine. 

Fresh  cartilages  are  not  readily  susceptible  of  colouring.  Place  them  in  absolute 
alcohol  or  in  MuUer's  fluid,  and  then  in  alcohol,  and  lastly  stain  with  hfematoxylin. 
Mount  in  glycerine.  Dammar  illuminates  too  strongly,  and  causes  the  finer  details 
to  disappear. 

50.  Elastic  Cartilage,  Method  Xo.  50,  p.  330.  Take  a  cartilage  from  the 
larynx  of  an  ox.  The  yellowish  colour  of  the  processus  voccdis  shows  elastic 
cartilage.  Cut  in  such  a  manner  that  the  boundary  between  elastic  and  hyaline 
cartilage  falls  in  the  section,  and  examine  the  sections  in  water.  Preserve  in 
glycerine.  The  development  of  elastic  fibres  may  also  be  studied  in  the  cartilages 
of  adult  persons,  especially  in  that  of  the  epiglottis  and  in  the  processus  vocalis  of 
the  arytenoid  cartilages.  This  kind  of  cartilage  stains  well  with  picrocarmine, 
the  cells  being  stained  red  or  pink  and  the  elastic  substance  yellow.  Mount 
stained  sections  in  dammar. 

51.  Connective  Tissue  Cartilage,  Method  No.  51,  p.  330.  An  intervertebral 
disc  of  an  adult  man  is  cut  into  portions  of  1  to  2  cm.  broad,  fixed  for  twenty-four 
hours  in  100  c.cm.  of  Kleinenberg's  sulpho-picric  acid,  and  hardened  in  50  c.cm. 
of  alcohols  of  increasing  strengths.  After  three  days'  immersion  in  90  per  cent. 
alcohol,  the  bits  are  coloured  strongly  with  borax  carmine  (p.  262),  again  hardened 
in  alcohol  and  then  cut.  Preserve  in  dammar.  Sections  through  parts  of  the 
margin  also  show  hyaline  cartilage  ;  sections  of  the  central  parts  of  the  disc  show 
groups  of  cartilage  cells. 

52.  Bone,  Method  No.  52,  p.  332.  Bones  to  be  used  for  sections  should  not 
be  dried  previous  to  maceration,  but  must  be  immersed  fresh  for  several  months  in 
water,  which  is  several  times  changed.  After  they  have  been  dried,  a  portion  is 
fixed  in  a  screw-vice  between  two  pieces  of  cork  or  layers  of  cloth,  and  a  trans- 
verse lamina,  1  to  2  mm.  thick,  is  cut  ofli'  with  a  thin  leaf  saw.  The  lamina  is 
firmly  attached,  by  means  of  sealing  wax,  to  the  lower  surface  of  a  cork  stopper 
(the  sealing  wax  must  entirely  cover  the  lamina),  the  whole  is  dipped  one  moment 
into  water,  and  then  filed  quite  even  with  a  fine  flat  file ;  then,  by  heating  the 
sealing  wax,  detach  the  lamina  of  bone  and  stick  the  smoothed  side  on  to  the 
stopper.  The  lamina  is  again  operated  upon  by  the  file,  until  it  has  become  so 
thin  that  the  sealing  wax  shines  through.  Then  lay  the  whole  in  90  per  cent. 
alcohol,  where,  in  a  few  minutes,  the  lamina  of  bone  is  easily  detached.  Now 
take  a  coarse  whetstone,  moisten  it  with  water  ;  produce  by  means  of  rubbing  with  a 
second  whetstone  a  little  paste.  Place  the  bone  lamina  in  it,  and  rub  it  on  both 
sides  with  a  circular  motion.  When  the  lamina  has  attained  the  requisite  thinness 
— the  operator  may  satisfy  himself  as  to  this  by  drying  it  between  filter  paper 
and  then  inspecting  it  with  a  low  power — smooth  it  on  both  sides  upon  a  fine 
whetstone  (the  method  is  exactly  similar  to  that  of  rubbing  on  the  coarse  whet- 
stone) ;  next  dry  it  with  filter  paper  and  polish  it  on  the  sides.     To  do  this,  nail 

I.  2  I 


4,98  APPESDIX  J. 

■A  small  portion  of  deerskin  (wash-leather)  smoothly  upon  a  board,  chalk  the 
leather,  and  rub  the  lamina  up  and  down  with  a  little  saliva  on  the  tip  of  the 
finger.  The  dull  lamina  soon  acquires  a  glittering  upper  surface.  Finally, 
remove  the  adhering  chalk  by  rubbing  on  fine  wash-leather.  The  lamina  is  dried 
and  placed  under  a  cover-glass,  which  is  then  sealed  round  with  cement. 

53.  Bone,  see  Method  Xo.  52. 

54.  Haversian  Canals  and  Bone  Lamell.*;.  Make  longitudinal  and  transverse 
sections  through  the  bone,  which  has  been  decalcified  according  to  the  fixation  and 
hardening  method,  in  3  to  9  per  cent,  nitric  acid,  and  again  hardened.  For  this 
purpose  select  a  metacarpal  bone  of  a  growing  individual.  Compact  portions  of 
larger  bones  [e.g.  the  femur)  require  too  long  a  time  (several  weeks)  for  decalci- 
fication. Let  the  periosteum  remain  on  the  bone.  For  longitudinal  sections  of 
the  Haversian  canals  very  thick  sections  ( 'o  mm.  and  more)  are  prepared,  which 
must  be  preserved  in  dilute  glycerine.  For  transverse  sections  and  systems  of 
lamellae  do  not  use  very  thin  sections ;  the  lamellae  are  best  perceived  if  we 
examine  the  section  in  a  few  drops  of  distilled  water,  and  turn  the  mirror  in  such 
a  manner  that  the  object  is  only  half  illuminated.  We  then  also  perceive  the 
delicate  striae  caused  by  the  small  bone  canals,  which  run  perpendicularly  to 
the  lamella?.  Preserve  in  dilute  glycerine,  which,  however,  renders  the  lamella' 
systems  partly  indistinct.  It  is  not  every  part  of  the  bone  which  displays  entire 
systems  of  lamelliB  ;  thus  the  outer  and  also  the  inner  ground  lamellae  are 
frequently  absent.  If  sections  are  made  near  the  epiphyses  we  perceive  how  the 
compact  substance  is  continued  into  the  small  trabecuhe  of  the  substantia  spongiosa. 
We  not  seldom  find  that  the  concentric  rings  of  the  Haversian  lamellre  are  divided 
by  an  irregular  line.  The  bone  already  formed  has  been  again  re-absorbed  up  to  this 
line.  All  that  lies  within  the  line  is  newly  added  bone.  These  formations  arc 
called  Haversian  spaces. 

55.  Bone,  Method  No.  55,  see  Methods  No.  52  and  54. 

56.  Bone  Marrow.  Procure  from  the  slaughter  house  the  vertebra  (cut  in 
halves)  of  a  newly  killed  calf  ;  scrape  off  with  a  scalpel  the  spongy  bone  substance, 
and  take  a  little  of  the  red  bone  marrow  from  the  deeper  part  of  the  spongiosa. 
Take  only  a  little  marrow,  as  much  as  covers  the  point  of  the  knife.  Place  a 
little  in  a  drop  of  salt  solution  on  a  slide,  stir  round  with  a  needle,  and  after  a 
small  piece  of  hair  has  been  placed  in  the  preparation,  cover  with  a  cover-glass. 

Usually  there  lie  in  the  preparation  a  few  small  bone  trabecule  of  the 
spongiosa,  which  prevent  the  cover-glass  from  lying  smoothl3\  The  larger 
trabeculag  or  spicules  must  be  removed  with  a  needle  previous  to  covering  the  pre- 
paration. If  we  examine  with  a  high  power,  we  perceive  over  and  above  the  small 
trabeculae,  fat  cells  and  red  blood  corpuscles,  marrow  cells  of  various  sizes  and 
giant  cells,  but  not,  or  only  seldom,  any  nuclei.  Now  let  a  few  drops  of  picro- 
carmine  flow  into  the  preparation  ;  the  nuclei  become  red  after  1  to  2  minutes,  but 
they  are  still  pale.  If  we  replace  the  picrocarmine,  first  by  means  of  salt  soluticm 
and  next  by  dilute  acidulated  glycerine,  the  nuclei  become  dark,  and  sharply  out- 
lined. A  hair  placed  below  the  cover-glass  prevents  many  cells  from  floating  away. 

57.  Sharpey's  Fibres.  Decalcify  a  hardened  humerus,  with  periosteum 
adhereat,  of  a  new-born  human  subject,  in  3  per  cent,  nitric  acid  (6  c.cm.  of  nitric 
acid  in  200  of  distilled  water),  and  make  delicate  transverse  sections  through  the 
diaphyses.  These  may  be  teazed  in  a  drop  of  salt  solution.  With  a  high  power  we 
perceive  in  certain  jDla^ces  the  pale  fibres  standing  out  freely.  The  fibres  may 
also  be  seen  on  the  surface  of  unteazed  sections.     The  fibres  are  very  pale  and 


METHODS  OF  2IAKIXG  HISTOLOGICAL  PREPARATIONS.    499 

rise  but  little  above  the  level  of  the  section.  One  may  also  see,  after  some  practice, 
intersected  fibres  on  both  longitudinal  and  transverse  sections.  Staining  does  not 
help  much  in  identifying  the  fibres,  as  fibres  and  bones  take  the  colour  almost 
equally.     Try  picrocarmine  and  preserve  in  dilute  (not  acidulated)  glycerine. 

08.  OssiFiCATiox,  Method  No.  58,  p.  338.  For  preparations  showing  bone 
development,  human  embryoes  of  four  to  five  months,  and  embryoes  of  animals, 
sheep,  sow,  or  ox,  from  10  to  14  cm.  long,  are  suitable.  The  latter  can  be  with- 
out difEculty  procured  from  slaughter  houses.  Procure  the  entire  uterus,  place 
a,ll  the  embryoes  (2  to  3  portions  in  1  litre)  for  four  weeks  in  Miiller's  fluid. 
Change  frequently.  Then  wash  for  one  hour  under  water  tap,  and  harden  them 
in  200  to  400  c.cm.  of  alcohol  of  increasing  strengths.  After  the  embryoes  have 
lain  one  week  or  longer  in  90  per  cent,  alcohol,  cut  off  the  head,  and  the  extremities 
close  to  the  trunk,  and  place  them  for  decalcification  in  200  c.cm.  of  distilled 
water,  to  which  2  to  4  c.cm.  of  pure  nitric  acid  have  been  added.  After  two  to 
five  days,  during  which  the  decalcifying  fluid  has  been  changed  about  three 
times,  the  extremities  are  taken  out  (the  head  is  not  yet  completely  decalcified, 
and  must  remain  a  few  days  longer  in  2  per  cent,  nitric  acid),  washed  for  one  to 
two  hours  under  water  tap,  and  once  more  hardened  in  alcohol  of  increasing 
strengths.  After  they  have  been  about  five  days  in  90  per  cent,  alcohol,  cut  the 
extremities  into  portions  1  cm.  long,  and  place  these,  if  they  should  be  still  too 
soft,  for  one  to  two  days  in  30  c.cm.  of  absolute  alcohol.  For  preparations  show- 
ing the  early  stages  of  bone  development,  make  longitudinal  sections  directed 
through  the  phalanges  and  metacarpal  bones.  Good  sections  should  pass  through 
the  axes  of  the  extremities  ;  marginal  sections  are  not  so  good.  For  the  more  ad- 
vanced stages,  make  special  transverse  sections  through  the  humeri;s  and  the 
femur.  Sections  through  the  diaphyses  show  perichondral,  and  sections  through 
the  epiphyses  show  enchondral,  bone  formation.  The  most  beautiful  O'iteohlaxI a 
<ire  found  in  transverse  sections  of  the  lower  jaw.  This  bone  is  also  adapted  for 
preparations  illustrating  development  of  tooth.  For  still  later  stages,  small  por- 
tions of  the  skeleton  of  newly  born  animals  must  be  employed,  the  phalanges 
still  exhibit  early  processes.  Such  bones  require  longer  time  for  decalcification 
(eight  days).  For  the  formation  of  bone  in  connective  tissue  membrane,  cut 
surface  sections  through  the  parietal  and  frontal  human  bones.  The  sections  are 
placed  for  ten  minutes  in  4  c.cm.  hsematoxylin  ;  transferred  for  ten  minutes  into 
10  c.cm.  of  distilled  water  ;  next  stained  for  10  minutes  in  4  c.cm.  picrocarmine; 
then  brought  for  a  quarter  of  an  hour  into  20  c.cm.  of  distilled  water,  and  lastly 
placed  for  preservation  in  absolute  alcohol,  lavender  oil,  and  dammar.  If  the 
staining  process  has  succeeded,  cartilage  will  appear  blue  and  bone  red.  Some- 
times the  cartilage  may  not  have  acquired  the  vivid  blue  tint.  *In  that  event, 
place  the  sections  in  5  c.cm.  of  distilled  water,  to  which  have  been  added  5  drops 
■of  filtered  solution  of  haematoxylin.  The  cartilage  will  become  blue  if  left  in  this 
solution  for  six  to  fourteen  hours.  Picrocarmine  staining  is  sometimes  not  very 
uniform  in  the  case  of  bone. 

59.  Ossification.     See  Method  No.  58. 

60.  Ossification.     See  Method  No.  58. 

61.  Ossification.     See  Method  No.  58. 

62.  Ossification.     See  Method  No.  58. 

63.  Ossification.     See  Method  No.  58. 

64.  Ossification.     See  Method  No.  58. 

.65.  Bundles  of  Transversely  Striated  ^Iuscle,  Method  No.   65,  p.  SoG. 


500  APPENDIX  L 

Make  with  a  sharp  razor  in  a  parallel-fibred  muscle  (e.;/.  an  adductor  of  the  rabbit) 
a  deej)  incision  directed  transversely  to  the  course  of  the  fibres,  and,  at  2  to  8 
cm.  downwards  from  this,  a  second  incision.  Connect  both  by  longitudinal 
sections,  and  prepare  without  tearing  the  portion  so  circumscribed.  Fix  in  100 
c.cm.  1  per  cent,  solution  of  chromic  acid.  After  the  lapse  of  fourteen  days,  wash 
for  two  or  three  hours  under  water  tap,  and  then  harden  in  50  c.cm.  of  alcohol  of 
increasing  strengths.  Transverse  sections  are  to  be  examined  unstained  in  dilute 
glycerine.  We  perceive  muscle  fibres  of  different  degrees  of  thickness.  Although 
the  muscle  fibres  are  cylindrical,  and  consequently  round  when  in  transverse 
section,  they  here  appear  irregularly  polygonal  on  account  of  reciprocal  pressure. 
The  colour  of  the  transverse  sections  is  very  various,  some  being  entirely  dark, 
others  quite  clear.  The  perimysium  of  individual  muscle  fibres  is  better  seen 
under  high  powers. 

66.  Muscle  and  Tendon,  Method  No.  6G,  p.  357.  Remove  from  a  newly 
killed  frog  the  skin  of  the  lower  part  of  the  thigh,  cut  off'  with  a  pair  of  scissors 
the  bone  above  the  knee  joint  (the  origin  of  the  gastrocnemius),  and  fix  the  lower 
part  of  the  thigh  and  the  foot  in  50  c.cm.  of  Kleinenberg's  sulpho-picric  acid. 
After  twenty -four  hours,  place  it  in  50  c.cm.  of  70  per  cent,  alcohol,  with  a  view  to 
gradual  hardening.  After  six  days,  cut  off  the  gasti-ocnemius  along  with  a  por- 
tion of  the  tendo  Achillis,  place  it  for  staining  in  borax  carmine,  and  then 
harden  repeatedly  with  90  per  cent,  alcohol.  In  ciitting  (sagittal  or  longitudinal 
sections),  place  the  razor  first  of  all  on  the  tendinous  surface  on  the  posterior  sur- 
face of  the  muscle.  Mount  in  dammar.  The  transverse  striation  on  the  muscle 
fibres  often  disappears. 

67.  Muscular  Fibke  of  Intestine,  Method  No.  67,  p.  358.  Eemove  the 
stomach  and  duodenum  of  a  cat  about  one  hour  after  death,  open  both  length- 
ways, remove  the  contents  by  means  of  gentle  movement  in  salt  solution,  and 
immerse  the  pyloric  portion  and  the  upper  half  of  the  duodenum  (a  portion  5  to  (> 
cm.  long)  for  three  to  six  days,  in  100  to  150  c.cm.  of  0'5  per  cent,  solution  of 
chromic  acid.  Make  longitudinal  sections,  stain  with  ha?matoxylin,  preserve  in. 
glycerine  or  dammar.  (As  to  further  details  in  treating  sections  of  portions  of 
intestinal  canal,  see  Appendix,  Vol.  II.) 

68.  Motor  Nerve  Terminations,  Method  No.  68,  i5.  358.  (a)  End  PlateK, 
Cut  out  a  thin  portion,  1  cm.  long,  of  the  muscles  of  a  lizard  or  the  short  muscles 
(intercostal  or  ocular  muscles)  of  small  quadrupeds.  Prepare  a  mixture  of  chloride 
of  gold  and  formic  acid ,  boil  it  and  let  it  cool.  Place  the  bit  of  muscle  in  it  for 
one  hour  in  the  dark.  Transfer  the  small  portions  at  the  end  of  that  tim&  into 
10  c.cm.  of  distilled  water,  ahd  after  a  few  minutes  into  a  fresh  portion  of  water 
to  which  a  few  flrops  cf  formic  acid  have  been  added,  then  expose  to  daylight  (not 
sunlight)  for  twenty-four  to  forty-eight  hours.  The  portions  of  muscle  will  now 
have  a  dark  violet  tint.  Then  transfer  them  for  hardening  into  30  c.cm.  of  alcohol 
of  increasing  strengths.  After  the  dai'k  violet  portions  of  muscle  have  lain  three 
to  six  days  in  alcohol,  teaze  the  bundles,  2  mm.  thick,  of  muscle  fibres  in  a  drop  of 
dilute  glycerine,  to  which  a  small  dr-op  of  formic  acid  has  been  added.  On 
account  of  the  brittleness  of  the  muscle  fibres  this  process  may  not  be  successful. 
A  light  pressure  on  the  cover-glass  is  often  of  advantage.  Low  powers  show 
nmscle  fibres  from  a  delicate  rose-red  hue  up  to  a  deep  purple  tint,  others  again 
of  red- violet  up  to  light  blue-violet ;  in  the  latter  we  may  notice  the  end  plates 
most  distinctly.  In  order  to  find  these  out,  follow  the  deep  black  nerve  fibres 
already  discernible  with  low  powers.     (6)  Nuchi  of  the  Motor  Plate.     Place  the 


METHODS  OF  MAKING  HISTOLOGICAL  PREPARATIONS.  501 

anterior  halves  of  the  muscles  of  the  eye  of  a  freshly  killed  rabbit  in  97  c.cm.  of 
distilled  water  +  3  c.  cm.  of  acetic  acid.  After  six  hours  transfer  the  muscles  into 
distilled  water,  cut  off  a  flat  small  piece  with  the  scissors  and  spread  it  out  on 
a  slide.  We  may  now  perceive  with  the  naked  eye  the  raniificatioias  of  the  white 
looking  nerve ;  with  low  power  (50  d. )  we  notice  the  anastamoses  of  the  nerve 
fibres.  The  blood-vessels  are  also  easily  discernible  by  their  transverse  nuclei 
(belonging  to  the  smooth  muscle  fibres  in  their  walls).  The  discovery  of  the  end- 
plates  is  not  easy  on  account  of  the  great  number  of  sharply  outlined  nuclei,  which 
belong  to  the  muscles,  the  intermusciilar  connective  tissue,  etc.  Follow  a  nerve 
fibre  and  one  may  notice  that  its  meduUated  sheath  suddenly  ceases  and  is 
apparently  lost  in  a  group  of  nuclei.  These  are  the  nuclei  of  the  motor  end-plate. 
m.  Ex\d-Plate,  Method  No.  69,  p.  358.     See  Method  No.  68. 


APPENDIX  II. 

CHEMISTRY  OF  MUSCLE. 

The  account  of  the  chemical  composition  of  muscle  given  at  p.  360  is  founded 
•chiefly  on  the  researches  of  Kiihne  on  the  plasma  obtained  from  the  muscles' of 
frogs.  Dr.  W,  D.  Halliburton,  in  an  elaborate  research,  has  investigated  the 
chemical  composition  of  the  muscles  of  warm-blooded  animals  ^  (rabbit,  horse),  and 
he  has  largely  extended  our  knowledge  of  the  subject.  He  succeeded  in  obtaining 
plasma  from  the  muscles  of  the  rabbit  by  washing  out  the  blood  from  the  vessels  by  a 
stream  of  cold  salt  solution  ( "6  per  cent,  salt  solution  at  a"  C. ),  then  placing  pieces  of 
the  muscles  in  a  freezing  mixture  of  ice  and  salt  having  a  temperature  of  -  12°  C, 
and  then  subjecting  frozen  slices  to  pressure.  A  yellowish,  somewhat  viscid  fluid, 
of  a  faintly  alkaline  reaction,  was  thus  obtained,  which  "set  into  a  solid  jelly  in  the 
course  of  from  one  to  two  hours  ;  at  a  temperature  of  40°  C.  coagulation  takes  con- 
.siderably  less  time,  viz. ,  twenty  to  thirty  minutes  :  simultaneously  an  acid  reaction 
is  developed."  Solutions  of  neutral  salts  prevent  coagulation  of  the  plasma. 
Dilution  of  "  salted  muscle  plasma  causes  coagulation.  Saline  extracts  of  rigid 
muscle  differ  from  salted  muscle  plasma  in  being  acid,  but  resemble  it  very  closely 
in  the  way  in  which  myosin  can  be  made  to  separate  from  it ;  myosin,  in  fact, 
undergoes  a  recoagulation."  The  separation  of  the  plasma  into  clot  and  "  salted  " 
muscle  serum  "does  not  take  place  at  0°  C.  ;  it  occurs  most  readily  at  the  tem- 
perature of  the  body,  and  is  hastened  by  the  addition  of  a  ferment  prepared  from 
muscle  in  the  same  way  as  Schmidt's  ferment  is  prepared  from  blood."  - 

According  to  Dr.  Halliburton,  the  proteids  of  muscle  plasma  are — 

1.  Paramyosinogeti,  coagulated  by  heat  at  47^  C. 

2.  Myosinogen,  coagulated  at  56°  C. 

3.  Myoglobulin,  differing  from  serum  globulin  in  its  coagulation  temperature 

(63°  C). 

4.  Albumin,  apparently  identical  with  serum  albumin  a,  coagulating  at  73°  C. 
^W.  D.  Halliburton,  M.D.,  B.Sc,  Assist.  Professor  of  Physiology,  University 

■College,  London:  "On  Muscle  Plasma,"  Journal  of  Physiology,  vol.  viii.  No.  3. 
"  Halliburton,  "  On  Muscle  Plasma,"  Proceedings  of  Royal  Society,  vol.  xlii. 


502 


APPENDIX  J  J. 


5.  Mjo-albuu)osc,  having  the  inoperties  of  deuteio-albuiiiose,  aiul  identical 
with,  or  closely  related  to,  the  myosin  ferment. 
The  two  first  bodies  form  myosin  clot  and  the  other  three  remain  in  the  muscle 
serum.  The  three  first  bodies  are  globulins,  "  completelj-  precipitated  by  satura- 
tion -with  magnesium  suljihate  or  sodium  chloride,  or  by  dialyzing  out  the  salts 
from  their  solutions."  Dr.  Halliburton  has  also  made  the  remarkable  observation 
that  "  when  muscle  turns  acid  (by  the  formation  of  lactic  acid),  as  it  does  during 
ritjor  mortis,  the  pepsin  which  it  contains  is  enabled  to  act,  and  at  a  suitable 
temperature  (35°  to  40"  C. )  albumoses  and  peptones  are  formed  by  a  process  of  self- 
digestion.  It  is  possible  that  the  passing  off  of  nV/or  mortis,  which  is  apparently 
due  to  the  reconversion  of  myosin  into  myosinogen,  may  be  the  first  stage  in  the 
self-digestion  of  muscle." 

Dr.  Halliburton  has  constructed  the  following  table  showing  how  these  pro- 
teids  may  be  separated  from  muscle  plasma,  which  he  has  given  me  his  kind 
permission  to  copy — 

Salted  Muscle  Plas3l\. 

Dilute  to  six  times  its  volume,  and  expose  this  to  a  temperature  of  85  C.  for 
one  or  two  honis,     It  separates  into  clot  and  salted  muscle  serum.     Filter. 


Clot :  consists  of  Myosin.  AVash  with 
Avater,  redissolve  in  5  per  cent,  magne- 
sium sulphate  solution.  Heat  to  47^  C. 
A  precipitate  is  produced.     Filter. 


SaJtcd  miisch'  serum  :  contains  myoglo- 
bulin,  albumin,  and  myo-albumose. 
.Saturate  with  magnesium  sulphate  or 
sodium  chloride.  A  precipitate  is  pro- 
duced.    Filter. 


Precipitate  :  con-  Filtrate  :  contains 
sists  of  Pakamyo-  M  y  o  s  t  X  o  g  e  X , 
sixoGEN.  which   is   precipi- 

tated at  56'^  C. 


Precipitate:  con- 
sists of  Myoglo- 
bflin. 


Filtrate  :  contains- 
albumin  and  myo- 
albumose.  Heat  to 
73"  C.  A  preci- 
pitate is  produced. 
Filter. 


Precipit-  Filtrat<- : 
ate :  con-  contains 
sists       of    My'o-Al- 

ALHrillN.       BUMCSE. 

As  regards  the  muscle-ferment,  Dr.  Halliburton's  conclusions  are  as  follows  : — 

"1.  By  keeping  muscle  under  alcohol  for  some  months,  most  of  the  proteids 
are  coagulated.  "Water  will,  however,  extract  from  the  alcoholic  precipitate  a 
proteid  which  has  the  characters  of  an  albumose. 

"2.  This  albumose  has  the  properties  of  a  ferment  in  caiising  the  coagulation' 
of  muscle  plasma,  or  it  may  be  that  the  ferment  is  in  very  close  combination  with, 
the  albumose. 

"  3.  This  myosin  ferment,  as  it  may  be  termed,  does  not  hasten  the  coagulation 
of  blood  plasma  ;  nor  does  fibrin  fennent  hasten  the  coagulation  of  muscle  plasma  ; 
the  two  are  therefore  not  identical. 

"  4.  The  juice  expressed  from  muscle,  however,  hastens  very  markedly  the- 
coagulation  of  salted  muscle  plasma.     This  is  not  due  to  its  containing  fibrin 


CHEMISTRY  OF  MUSCLE.  503 

ferment,  but  it  is  due  to  the  proteid  substance  myosinogen,  which  enters  into  the 
condition  of  heat  coagulum  at  56^  C.  Fibrin  ferment  is  absent,  or  only  present  in 
exceedingly  small  quantities. 

"5.  The  activity  of  fibrin  ferment  is  destroyed  at  75°  to  80°  C.  ;  the  activity  of 
myosin  ferment  is  not  desti'oyed  till  the  temperature  of  100°  C.  is  reached."^ 


APPENDIX  III. 

LATENT   PERIOD   OF   MUSCLE. 

Professors  Gerald  F.  Yeo  (King's  College,  London)  and  Theodore  Cash  (Aber- 
deen), after  an  elaborate  research  on  the  muscles  both  of  cold-blooded  and  of  wami- 
blooded  animals,  in  which  thej'  made  use  of  the  pendulum  myograph,  have 
arrived  at  the  following  conclusions — - 

"L  Increase  in  the  sti-enfjfh  of  the  ■■stmmlus  is  accompanied  by  (a)  a  steady  and 
gradual  shortening  of  the  latent  period  ;  (/3)  a  sudden  prolongation  of  the  actual 
contraction  when  a  certain  degree  of  stimulation  is  reached  ;  (7)  an  elevation  of 
the  altitude  of  the  curve  with  the  early  and  the  final  parts  of  the  increase ;  (5) 
and  a  removal  of  the  sunmiit  to  a  later  part  of  the  curve  as  soon  as  the  elongation 
of  the  curve  is  established. 

"  II.  Increase  in  the  iceighf  used  as  a  burden  for  the  muscle  is  accompanied  by 
(a)  elongation  of  the  latent  period  ;  (/3)  commonly  a  slight  shortening  of  the  dura- 
tion of  the  contraction  ;  (7)  depression  of  the  height  of  the  curve  ;  and  (5)  no 
marked  change  in  the  position  of  the  summit  except  in  extreme  cases. 

"III.  The  application  of  heat  causes  (a)  very  marked  and  continuous  shortening 
of  the  latent  period ;  (/3)  a  gradual  and  distinct  increase  in  the  height  of  the 
curve ;  and  (7)  a  more  rapid  arrival  at  the  summit,  followed  by  a  sudden  fall  of 
the  lever,  which  usually  passes  considerably  below  the  abscissa.  (Extreme 
warmth  has,  however,  an  opposite  effect;  when  above  90°  F. ,  the  altitude  gets 
lower  and  the  muscle  remains  contracted. ) 

"  IV.  Cooling  causes  (a)  the  latent  period  rapidly  to  increase  ;  (/3)  a  great 
increase  in  the  duration  of  the  contraction ;  (7)  at  first  a  slight  elevation  in  the 
altitude  (extreme  cold,  however,  lowers  it)  ;  (5)  the  initial  part  of  the  curve  is 
flattened,  and  the  summit  is  delayed  until  a  later  period. 

"V.  Gentle  activity  seems  to  increase  the  rate  and  power  of  contraction.  Very 
weak  interrupted  currents  have  an  effect  like  that  produced  by  gentle  beat.  If 
extreme  fatigue  be  induced,  (a)  the  latent  period  becomes  much  longer  ;  (j8)  the 
duration  of  the  contraction  is  increased  ;  (7)  the  height  of  the  curve  is  consider- 
ably lessened  ;  (5)  and  its  summit  is  moved  away  from  the  beginning  of  the  con- 
traction towards  the  end  of  the  curve." 

'  Journal  of  Physiology,  vol.  viii.  No.  3,  p.  182. 

-  Yeo  and  Cash — On  the  relation  between  the  active  phases  of  contraction  and  the 
latent  period  of  skeletal  muscle.     Journal  of  Phy-nology,  vol.  iv.  No.  2. 


505 


INDEX 


Abbe's  condensers,  figures  of,  256. 

Absorption,  co-efficient  of,  of  gases,  353 ;  of  fat 
by  epithelium,  3i!0  ;  of  fluids  by  epithelium, 
319  ;  of  gases  by  epithelium,  319. 

Accessory  appliances  to  microscopic  research, 
259,  260  ;  for  study  of  muscle,  376-381. 

Acetic  acid  series,  57,  161. 

Acetylene,  47. 

Acid,  acetic,  161,  163  ;  butsTric,  163  ;  capric,  163  ; 
caproic,  163  ;  caprylic,  163  ;  cholalic,  107,  108 ; 
cryptophanic,  106;  formic,  161 ;  glycocholic,  106, 
107;  glycollic,  16i ;  hippuric,  104,'l05, 106;  ino- 
.sinic,  106;  lactic,  165;  leucic,  166;  oleic,  16S  ; 
oxalic,  16(i,  167  ;  oxalic  series,  166  ;  oxycaproic, 
166;  palmitic,  163;  propionic,  163 ;  stearic,  103; 
succinic,  167;  sulphocyanic,  07;  taurocholic, 
107;  uric,  97,  98,  9;J,  100,  101,  102. 

Acids,  allylic  alcoholic  series,  167, 168;  bile  acids, 
tests  for,  lOS;  glycollic  series  of,  106,  107  ;  non- 
nitrogenous  organic,  57,  161 ;  organic  nitro- 
genous, 97,  162;  organic,  properties  of,  46,  48, 
49. 

Aconitine,  89. 

Actiniohajmatin,  144. 

Adamkievvicz,  reaction  of,  64. 

Adenoid  tissue,  structure  of,  328;  how  to  ex- 
amine, 496. 

Adipose  tissue  cells,  304,  305. 

Albumin,  acid,  75. 

Albumin,  alkali,  75;  decomposition  of,  16;  egg, 
73;  serum,  72,73;  chemical  composition  of,  81. 

Albumins,  true,  72. 

Albumin,  vegetable,  73. 

Albumins,  55,  72;  derived,  75. 

Albuminoids,  55 ;  crystallizable,  55,  76. 

Albuminous  derivatives,  55,  76;  preparation  of, 
76,  79, 

Aldehydes,  formulas  of,  46. 

Aldehyde,  formation  of,  48,  49. 

Alkaloids,  89. 

Allantoin,  54,  104. 

AUanturic  acid,  88. 

Alcohols,  57,  146 ;  formulae  of,  46 ;  composition 
of,  47;  diatomic,  4s. 

Alcohol,  ethyl,  47;  ethylic,  146 ;  propyl,  47 ;  oxid- 
ation of,  47,  48 ;  table  of,  162 ;  monatomic,  48  ; 
triatomic,  48. 

Aldehydes,  formation  of,  49. 

Amides,  49,  55,  84,  89,  90. 


Amines,  50,  55. 

Ammonium  salts,  in  secretions,  40. 
Amphioxus  embryo,  figures  of  sections  of,  245. 
Amyloid  matter,  77. 
Amyloses,  57,  159. 

Anisotropic  substance  of  muscle  fibre,  307. 
Anemometer,  d'Ons-en-Bray's,  383. 
Animists,  32. 
Amyloid  matter,  55. 
Aphidein,  144,  145. 
Aplysiopurpurin,  145. 
Archenteron,  formation  of,  245. 
Area  pellucida,  changes  in  the,  247,  248 ;  forma- 
tion of,  246. 
Aristotle,  definition  of  life,  31,  32. 
Aromatic  compounds,  47. 
Asparagine,  89. 
Assinailation,  nature  of,  294. 
Atomic  constitution  of  molecules,  50. 
Atomic  theory,  8. 
Atropine,  89. 

Ascaris  megalocephala,  division  of  egg  of,  233; 

polar  bodies  of,  229. 
Axis  cylinder,  313,  315 ;  how  to  examine,  493. 


B 


Bacillus  anthracis,  191,  192 ;  subtilis,  192  ;  ulna, 
192. 

Baeyeb,  on  formation  of  uric  acid,  97  ;  on  indol, 
110  ;  on  protagon,  82. 

Balance,  figure  of,  6. 

Balfocr,  on  heredity,  237 ;  on  the  muscle  ele- 
ments, 356. 

Baumank,  on  phenol,  149. 

Beadnis,  reference  to,  39,  40  ;  on  water  in  tissues, 
etc.,  36  ;  on  biliverdin,  131  ;  on  iron  in  secre- 
tions, etc.,  42;  on  nonstriated  muscle,  436; 
table  of  gases  in  body  fluids,  169;  on  sulphates 
in  tissues,  etc.,  43  ;  on  origin  of  urea,  86,  87. 

Bechajip,  on  alcohol,  146. 

Beclard,  definition  of  life,  31  ;  on  production  of 
heat  in  muscle,  422. 

Becqukrel's  theory  of  muscle  currents,  454,  455. 

Beneden,  Van,  on  polar  bodies,  228,  229 ;  on  seg- 
mentation in  rabbit  ovum,  245,  246. 

Be.veke,  on  glycerine,  148. 

Benzol,  16 ;  constitution  of,  51. 


506 


IXDEX. 


Bernarc's,  Claude,  method  of  iireparing  glj'co- 
gen,  159  ;  on  irritability  of  muscle,  400,  401. 

Bkrnstein,  on  action  stream,  458  ;  on  muscle  con- 
traction, 453;  on  negative  variation,  452. 

Berzeliu.s,  on  fermentation,  177. 

Bezold,  Vox,  on  muscle  contraction,   453 ;    on 

negative  viiriation,  45:;. 
Biberine,  89. 

BiCHAT,  definition  of  life,  31. 
Bichromate  voltaic  element,  37.. 

BiEDERMANx's  fluid  in  muscular  contraction,  420, 
4-Jl. 

Bile,  acids  of,  56,  106,  107,  los,  lOli ;   tests    for, 

108  ;  pigments  of,  56,  V.W. 
Bilicyauin,  133. 
Bilifuscin,  13l'. 
BilOiumin,  133. 
Biliprasin,  132. 
Bilirubin,  130,  131. 
Biliverdin,  131. 

Billroth,  on  production  of  heat  in  m\isclc,  423. 
Biology,  general  principles  of,  13. 
Biijolar  nerve  cells,  313. 

BiscHOFF,  on  quantity  of  water  in  the  body,  35. 
Black  pigments,  142. 
Blaxkexiiorx,  on  protagon,  82. 

Blastoderm,  244 ;  formation  of,  246 ;  of  hen's 
ovum,  figures  of  section  of,  246. 

Blastodermic  layei-s,  formation  of,  244-252  ;  ves- 
icle of  rabbit,  figures  of,  251. 

Blastomeres,  244. 

Blastopore,  formation  of,  245. 

Blood  corpuscles,  mode  of  examining,  480  ;  struc- 
ture of,  300 ;  crystals,  how  to  examme,  490 ; 
plaques,  how  to  demonstrate,  489 ;  pigments, 
56  ;  stains,  how  to  examine,  490. 

Blue  pigments  of  bile,  133. 

Boeruaave,  theory  of  life,  32. 

Bogomoloff's  test  for  bile  acids,  lOS. 

BoRoaxv,  on  chemical  actions  of  i)roteids,  60  ;  on 
proteids,  63. 

Bone,  332-342  ;  chemical  composition  of,  342,  343; 
development  of  336-341  ;  how  to  examine,  497 ; 
matrix,  324  ;  ossification,  337  :  structure  of,  332, 
337  ;  lamellaj,  how  to  examine,  498  ;  marrow, 
how  to  examine,  498. 

Borelli,  theory  of  life,  32. 

BoscoviTCH,  on  atomic  theory,  8. 

BoTTOER-'s  test  for  glucose,  153. 

Boussole,  442. 

Bowman,  sarcous  element  of,  309. 

Bristle  cells,  how  to  demonstrate,  491. 

Brittner,  on  animal  and  vegetable  proteids,  71. 

Brownian  movement  of  cells,  296. 

Browx-SIqi'ard,  on  muscular  irritability,  404  ;  on 
rigor  mortis,  432. 

Brucine,  89. 

BRrcKE,  on  muscle  substance,  309  ;  metliod  of 
preparing  glycogen,  160. 

Budding  in  cell  formation,  297. 

BuF'KON,  on  spermatozoa,  214,  215. 

BuxGE,  analysis  of  soda  and  potash  in  enibryo 
mammals,  40  ;  on  hippuric  acid,  106. 

BrxsEN's  voltaic  element,  369,  .^70. 

Burdach,  on  percentage  of  fat  in  body,  150. 


B  urdon-Sandkr.sox,    on  electric  organs  of  raia 

batis,  470,  471,  477  ;  on  polar  bodies,  227. 
Butyric  acid,  W.\. 


Cadaveric  rigidity,  plionoinena  of,  432,  433. 

Caffein,  89. 

Cagniard  de  la  Tour,  on  fermentation,  177. 

Camera  lucida,  figure  of,  259. 

Canaliculi  of  bone,  332. 

Canalis  neurentericus,  fcirmation  of,  245. 

Cane  sugar,  158. 

Capric  acid,  57,  163. 

Caproic  acid,  57,  163. 

Caprylic  acid,  57,  163. 

Carbohydrates,  151 ;  classification  of,  151. 

Carbon  compoimds,  properties  of,  54  ;  in  organic 
compounds,  45. 

Carbonates,  in  the  body,  42. 

Carbonic  acid  gas,  occurrence  of,  in  body,  170. 

Carbonic -oxide  haemoglobin,  124. 

Carburetted  hydrogen,  occuiTcnce  of  in  body,  170. 

Carnin,  104. 

Carotin,  139. 

Carpenter,  on  vital  energy,  20. 

Cartilage,  chemical  composition  of,  331  ;  develop- 
ment of,  331  :  how  to  examine  hvaline,  497  ; 
structure  of,  328,  329,  330,  331  ;  white  fibro,  330, 
331 ;  yellow  fibro,  330. 

Casein,  75. 

Cash,  Theodore,  on  latent  period  of  muscle,  503.. 

Cells,  of  adipose  tissue,  304,  305;  structure  of,  299, 
317;  characters,  etc.,  of,  292-298;  coloured 
blood,  299,  300,  301  ;  connective  tis.sue.  206, 
303,  304  ;  division  of,  212,  213,  214  ;  embryonic, 
207  ;  epithelial,  301,  302,  303  ;  evolution  of,  298;. 
figure  of,  903  ;  form  of,  293,  294  ;  general  theory 
of,  292,  293  ;  growth  of,  298  ;  irritability  of, 
295  ;  migrations  of,  295  ;  movement  of,  295  ; 
muscle,  305-313  ;  nerve,  313,  314 ;  nutrition  of,. 
294,  295 ;  reproduction  of,  296,  297  ;  size  of. 
294  ;  structure,  details  of,  207-212  ;  structure, 
different  views  of,  206,  207,  20S,  209. 

Celloidin,  use  of,  in  section  cutting,  287. 

Cellular  excretion,  nature  of,  295  ;  secretion- 
nature  of,  295. 

Cellulose,  occurrence  of,  16,  100,  161. 

Cerebrin,  55,  82,  83. 

Cerebrin-pseudo,  S3. 

Chauveau,  on  fermentation,  182. 

Chemical  composition  of  bone,  342,  343. 

Chemical  constitution  of  muscle  fibre,   300-363. 

Chemical  forniulw,  determination  of,  52. 

Chemical  instability,  16. 

Chemical  stimuli  in  muscular  contraction,  419,. 
420. 

Chemical  reactions  in  the  living  organism,  170. 

Chemicals,  influence  of,  in  fermentation,  194. 

Chemistry,  of  the  body,  34  ;  relation  to  physi- 
ology, 3. 

Chevreil,  on  nitrogen  in  body,  168. 

Chlorocruorin,  143. 

Chlorophane,  spectrum  of,  140. 

Chlorophyll,  occurrence  of,  23,  142,  143. 

Cholalic  acid,  56,  107,  108. 

Cholesterin,  146,  147. 


INDEX. 


507 


Choletelin,  131,  132. 

Cholin,  55,  82,  S3. 

Cholohsematin,  spectrum  analj-sis  of,  132. 

Choloidio  acid,  56. 

Chondi-igen,  55,  79. 

Chondrin,  79,  SO  ;  chemical  composition  of,  SI. 

Chondroglucose,  SO,  157. 

Chorda  dorsalis,  formation  of,  248. 

Chromatin  filaments, arrangement  of  inovum,232. 

Chromophanes,  140. 

Chronographs,  385-387. 

ChronogTaphy,  384-889. 

Chdbcu,  on  turacin,  144. 

Cicatricula,  formation  of,  240. 

Ciliary  motion,  how  to  examine,  491  ;  nature  of, 

321,  322  ;  theories  of,  322  ;  varieties  of,  321. 
Cinchonine,  89. 
Cladothrix  dichotoma,  189. 
Clf.rk  Maxwell,  on  matter  and  motion,  11,  21  ; 

on  the  atom,  242,  243. 
Cochineal,  144. 
Codeine,  89. 
Cohesion    of    connective   tissues,    343,    344 ;    of 

muscle,  397,  09S. 
CoLEM-iN,  on  temperature  in  fermentation,  193. 
Collagen,  55,  79. 
Colloid  matter,  55,  66,  76,  77. 
Commutator,  Pohl's,  378,  379. 
Compound  substances  present  in  the  body,  35. 
Concretions,  origin  of,  17. 
Conine,  S9. 

Connective  tissue  cartilage,  how  to  examine,  497. 
Connective  tissue,  ground  substance  of,  323  ;  how 

to  examine,  494,  495;  physical  properties  of, 

343-345  ;  structure  of,  324  ;  vital  properties  of, 

346,  347. 
CoNRADi,  on  cholesterin,  146. 
Consistence  of  connective  tissues,  343  ;  muscle, 

397. 
Constitution  of  muscle  serum,  361,  362. 
Contact  theory  of  muscle  cun-ents,  456-458. 
Contractile  tissues,  355. 
Contraction   of  muscle,  modes  of  exciting,  418- 

421  ;  period  of,  407  ;  phases  of  single,  406-412  ; 

phenomena  of,  405-414. 
Contraction  wave  of  muscle,  propagation  of,  412- 

414. 
Costal  cartilage,  how  to  examine,  497. 
Creatin,  56,  94  ;  crystals,  figure  of,  94. 
Creatinin,  56,  94,  95  ;  crystals,  figure  of,  95  ;  test 

for,  95. 
Crustaceorubin,  144. 
Cryptophanic  acid,  56,  100. 
Crystalloids,  66. 

Crystals,  method  of  increase  of,  17. 
Curare,  action  of  on  muscle,  401. 
Current  in  a  living  man,  459. 
Cuticular  formations,  304. 
Cystin,  56,  97. 

D 

DAXiiiLL's  voltaic  element,  369. 
Darwin,  on  pangenesis,  235. 


Davy,  Sir  Humphrt,  on  heat,  11. 

Death,  result  of,  30. 

Decalcification  in  micros«opic  research,  268,  269. 

Decomposition,  in  the  living  organism,  173. 

Democritus,  atomic  theory  of,  S. 

Density  of  connective  tissues,  343. 

DepreZj  signal  of,  389. 

Deuthyalosome,  the,  230. 

Dextrin,  100. 

Dialyzer,  figure  of,  65. 

Diffusion  through  organic  membranes,  348-353. 

Direct  recording  of  movement,  389-394. 

Disassimilation,  nature  of,  294,  295. 

Discs,  nature  of  muscle,  307. 

Discus  proligerus,  222. 

DisQUE,  on  urobilin,  135. 

Dissociation,  definition  of,  173. 

DiTTMAR,  on  chemical  constitution,  51 ;  on  fer- 
mentation, 177. 

Dobie's  line,  nature  of,  309. 

DoxDERS,  on  dissociation,  173;  on  elasticitj-  of 
muscle,  399. 

D'ONS-EX-B ray's  anemometer,  383. 

Du  Bois-Retmond,  discoveries  of,  440, 442  ;  obser- 
vations of,  on  muscle  currents,  448,  452  ; 
mode  of  electrical  action  of  torpedo,  4S2  ;  myo- 
graph, 390,391;  on  polarization  currents,  479,480; 
rheocord  of,  451  ;  theory  of  muscle  currents, 
455,  456  ;  on  currents  in  living  man,  459  ;  on 
electric  shocks  of  fishes,  471,  472  ;  on  electric 
.shocks  of  malapterurus,  474, 475,  476  ;  on  special 
electric  phenomena  of  fishes,  477,  478,  479,  480. 

DuGEs,  definition  of  life,  31. 

Dumas,  on  fecundation,  223. 

DuscH,  on  fermentation,  179. 

Dynamical  characters  of  animals,  25,  26,  27;  of 
living  things,  20  ;  of  plants,  24,  25. 

Dynamometers,  427. 


E 

Ebxer,  on  origin  of  spermatozoa,  216,  217. 

Echinochromo,   143. 

Egg,  cleavage  of,  figure  of,  234  ;  division  of,  in  sea 

urchin,  233,  234. 
Elastic  cartilage,  330 ;  how  to  examine,  497. 
Elastic  fibres,  326,  327 ;  how  to  prepare,  494,  495. 
Elastic  intercellular  substance,  324. 

Elasticity  of  connective  tissues,  344,  345,  346 ;  of 
muscle,  398,  399,  400. 

Elastin,  55,  SO;  chemical  composition  of,  SI. 

Elective  affinity,  definition  of,  295. 

Electric  apparatus  in  study  of  muscle,  363-381. 

Electric  batteries,  305,  366. 

Electric  fishes,  461,  462  ;  general  electrical  pro- 
perties of,  471-477;  phenomena  of,  461-480; 
special  electric  phenomena,  477-480. 

Electric  organs,  of  gymnotus,  465-468  ;  malap- 
terurus electricus,  408-470 ;  raia  batis,  470, 
471 ;  torpedo  Galvani,  462-405. 

Electric  plates,  364. 

Electric  poles,  364. 

Electric  signals  in  measuring  time,  387,  388 
389. 

Electric  stimuli  in  muscular  contraction,  418. 

Electrical  induction,  373,  374. 


o08 


JA'DEX. 


Electrical  iiie:isurements,  methods  of,  31)8 ; 
phenomena  of  nmscle,  436-451) ;  resistance, 
nature  of,  3(54,  365,  366,  367. 
Electricity,  discovery  of  animal,  437  ;  definitions 
of,  363-368 ;  effect  of  upon  protoplasm,  2!>0  ; 
general  statement  of,  363-368. 
Electro-capillary  theory  of  muscle  currents,  454,    '< 

455. 
Electrodes,  nature  of,  364  ;  non-polarizable,  380 ; 

polarizable  of  Du  IBois-Ueyruoud,  379,  3S0. 
Electrolytes,  nature  of,  364. 

Electrometer,  Lipiamanu's  capillarj',  443,  444,445. 
Elements  of  the  bodj',  35. 
Embedding  of  tissues,  in  wax,  279 ;  in  paraffin, 

2V9. 
Embryo  of  newt,  figures  of  sections  of,  -248. 
Embryology,  definition  of,  3. 
Emmerlino,  on  indol,  110. 
Enchondrial  ossification,  337,  33S,  339. 
Endogenous  cell  formation,  297. 
Endosmometer,  34S. 
Eiidosmotic  equivalent,  348. 
Energy,  conservation  of,  10, 11 ;  in  muscular  con- 
tractions,  28,   29  ;    kinetic,   lo  ;    plant  versus 
animal,  27  ;  potential,  10 ;  relation  of  its  study 
to  physiology,  9 ;  vital,  Carpenter  on,  20;  vital, 
Le  Conte  on.   21 ;  vital,  JIayer  on,  20  ;  vital, 
older  views  of,  20. 
Engelmaxx,  disc  of  in  muscle,  309  ;  on  fermen- 
tation, 181 ;  on  muscular  contraction,  406  ;  on 
:ionstriated  muscle,  435  ;  on  vital  energy,  24. 
Environment,  definition  of,  31. 
Epiblast,     formation    of,    245,    247 ;    structures 

derived  from,  251. 
Epiplasm,  225. 

Epithelial  cells,  301,  302,  303;  how  to  examine, 
490,  491  ;  mode  of  examining,  4S9 ;  secreting, 
figure  of,  297. 
Epithelial  layers,  varieties  of,  302,  303. 
Epithelium,  ciliated,  318-320 ;  columnar  or  pris- 
matic, 318 ;   influence  of,  in  absorption,   319, 
320;    influence  of,  in  elimination,   319,    320; 
lammar  or  stratified,  317  ;  physical  properties 
of,  318,  319;  physiological  properiies  of,  317; 
.simple  ciliated,  303 ;  simple  cylindrical,  303  ; 
simple,   flat  or  squamous,   317 ;   simple   pave- 
ment,   302,    303  ;    spheroidal,    318  ;    stratified 
ciliated,  303;  stratified  cylindrical,  303  ;stratified 
pavement,  303  ;  vital  properties  of,  319. 
Ether  freezing  in  section  cutting,  282. 
Ethers,  compound,  49,  50. 

Evolution,  of  living  beings,  20,  30  ;  of  cells,  298. 
Ethyleno-lactic  acid,  165. 
EWALD,  on  Torpedo  Galvani,  463. 
Excitability  of  muscle,  400. 
Excretion,  cellular,  nature  of,  295. 


F«cal  pigments,  136. 

Falk,  on  physiological  action  of  water,  36. 

Faraday,  relations  of  magnetism,  etc.,  11. 

Fascial,  structure  of,  327. 

Fat  cells,  304, 305 ;  how  to  examine,  491 ;  crystals, 

figure  of,  149  ;  in  fibrillar  tissue,  326  ;  origin 

of,  151. 
Fatigtie  in  production  of  heat  in  muscle,  423,  424. 
Fats,  constitution  of  animal,  149,   150;    in  the 

body,  57  ;  the  animal,  149. 


Fatty  compounds,  47  ;  nitrogenous  matters,  55. 
Fecundation,  figvn-e  of,  225 ;  true,  230-234. 
Frdkr,  on  origin  of  urea,  87. 
Fkhi-ISc's  test  for  glucose,  152,  153. 
Fkltz,  on  decomposition  of  urea,  40. 
Fenestrated    membranes,    how  to  demonstrate, 

495. 
Ferment,  blood,  185. 

Fermentation,  definition  of,  175 ;  influence  of 
chemicals  in,  194;  influence  of  light  in,  193; 
inflvjence  of  ozone  in,  194  ;  influence  of  i)ressuro 
in,  194 ;  influence  of  temperature  in,  191-193  ; 
influence  of  water  in,  193;  nature  of,  175,  17tJ; 
test  for  glucose,  153  ;  theories  of,  ISO,  182. 
Fei-ments,  action  of,  16 ;  amjdolytic,  1S5  ;  chemi- 
cal, actions  of,  186-188  ;  chemically  acting,  186- 
188;  classification  of,  183;  hydrolytic,  184; 
inversive,  185  ;  organized,  actions  of,  185,  186  ; 
organized,  nature  of,  188191 ;  proteolytic,  184, 
185 ;  soluble,  55,  76  ;  soluble,  action  of,  183,  184  ; 
steatolytic,  185;  the  organised,  185. 
Fertilization,  discoverers  of,  223,  224 ;  history  of, 

223,  224. 
Fibrillar  connective  tissue,  325,  326. 
Fibrils,  nature  of  muscle,  307. 
Fibrin,  55,  74. 
Fibrinogen,  74. 
Fibrinoplastin,  74. 

FiCK,  on  prodiiction  of  heat  in  muscle,  423. 
Filtration  through  organic  membranes,  347. 
Fixing  fluids,  for  microscopic  research,  266-268  ; 

general  rules  for,  266. 
Fletcher,  on  albumin,  59. 
FoL,  on  polar  bodies,  227. 
Food  of  animals,  26  ;  of  plants,  sources  of,  21. 
Force,  definition  of,  9  ;  measurement  of,  10. 
Form,  organic,  16. 
Formed  connective  tissue,  326. 
Formic  acid,  161. 
Formless  connective  tissue,  326. 
Formulse,  chemical,  determination  of,  53 ;  deter- 
mination of,  52. 
Foster,  on  spectrum  of  reduced  and  oxj-hsemo- 

globiii,  123. 
Fkericiis,  on  oxalic  acid,  167. 
Frey,  on  hippuric  acid,  104. 
Frog,  mode  of  examining  ova  of,  489 ;  muscles  in 

limb  of,  355  ;  spermatozoids  of,  488. 
Feitscii,   on  gymnotus   electricus,   46.5-468 ;   on 
malapterurus  electricus,  468,  470  ;  on  torpedo 
Galvani,  464,  465. 

G 

Gaiffe's  voltaic  element,  371. 

Galactose,  157. 

Galkn,  on  life,  32.  • 

Galvani,  on  electricity,  437-439. 

Galvanism,  437. 

Galvanometer,  method  of  experimenting  with, 
446-4.54;  Thomson's  reflecting,  442,  443;  Wiede- 
mann's, 442. 

Gametes,  225. 

Gamoee,  on  alkali  albumin,  75 ;  analysis  of 
uuclein,  78;  on  cerebrin,  83;  on  choiidrin,  80; 
on  collagen,  79;  on  elastin,  80;  on  fibrinogen, 
74 ;  on  hasmoglobin,  118  ;  on  keratin,  SO  ;  on 
lecithm,  S2  ;  on  legumin,  75  ;  un  mucin,  78  ;  on 


INDEX. 


509 


neurin,  83  ;  on  action  of  nitrites  on  blood,  126 ; 
on  paraijlobulin,  74;  on  peptones,  TO;  on  pro- 
tagon,  82  ;  on  the  spectrum  of  blood,  116,  117  ; 
on  spectrum  of  oxyhemoglobin,  122 ;  on  solu- 
bility of  proteids,  etc.,  64. 

Ganglionic  nerve  cells,  how  to  examine,  4fi3. 

Gareod's  test  for  uric  acid,  102. 

Gases  of  the  body,  168  ;  absorption  of,  by  fluids, 
353,  354 ;  absorption  of,  by  membranes,  353, 
354 ;  effect  of,  on  protoplasm,  291 ;  in  fluids 
of  body,  table  of,  16H. 

Gaskell,  on  muscular  fatigue,  481. 

Gastrula,  formation  of,  245. 

Gat  Lussac,  on  fermentation,  176,  ITS. 

Gelatin,  79  ;  chemical  composition  of,  SI ;  chem- 
ical reactions  of,  81. 

Gemmation,  nature  of,  297. 

Germ  epithelium,  221 ;  origin  from,  30. 

Gland  cells,  nerve  endings  in,  484  ;  secreting, 
figure  of,  298. 

Globulins,  55,  73. 

Glucoses,  57,  152. 

Glucose,  estimation  of,  153-156;  synonyms  of, 
152  ;  tests  for,  152,  153. 

Glycerine,  147,  148;  physiological  significance, 
14S. 

Glycocholic  acid,  106,  107. 

Glycocin,  90,  91. 

Glycocholate  of  sodium  crystals,  figure  of,  107. 

Glycocholic  acid,  56. 

Glycoffen,  159, 160  ;  preparation  of,  159, 160 ;  tests 
for,  160. 

Glycol  series  of  acids,  164. 

Glycocolle,  55,  90,  91. 

GlycoUic  acid  series,  57,  164. 

Glycin,  90,  91. 

Gmelin's  test  for  bilirubin,  130. 

Goitre,  77. 

GoODSiR,  on  nature  of  physiology,  3. 

Gordon,  on  polarization,  67,  68. 

GORTER,  De,  theory  of  life,  32. 

Gorup-Besanez,  on  magnesium  salts  in  tissues, 
41 ;  on  percentages  of  fat  in  tissues  and  fluids, 
150  ;  on  proteids,  1  ;  on  oxidation,  171. 

GoTcn,  on  electric  shocks  of  electric  fishes,  472, 
473  ;  on  electric  shocks  of  malapterunis,  475, 
477  ;  on  electric  organs  of  raia  batis,  470,  471 ; 
on  irreciprocity  in  torpedo,  483  ;  on  secondary 
discharges  of  torpedo,  483. 

Graafian  vesicles,  219,  £21  ;  figure  of,  223  ;  struc- 
ture of,  2:;2. 

Graham,  on  colloidal  state,  13  ;  on  dialysis,  65. 

Graphic  method,  3S1-397. 

Gravimetric  estimation  of  glucose,  156. 

Grenet's  voltaic  element,  372. 

Ground  substance  of  connective  tissue,  323. 

Grove's  voltaic  element,  370. 

Growth  of  cells,  298  ;  of  living  things,  17  ;  mode 
of,  16. 

GscHEiDLEN,  On  creatiuin,  95  ;  on  preparation  of 
hcemoglobin,  119. 

Guanin,  103. 

Gymnotus  electricus,  465-468. 

Gun  cotton,  composition  of,  16  ;  instability  of,  16. 


H 


Haas,  on  albumin,  71. 


Hakckel,  on  heredity,  235. 

Hsematin  acid,  spectrum  of,  127  ;  alkaline,  spec 

trum  of,  127. 
Hasmatin,  126,  127. 
Hsematoidin,  128,  129;    crystals,  figure  of,  129 

how  to  examine,  490. 
Hsematolin.  128. 
Haamatoporphyrin,  127,  128  ;  acid,  spectrum  of, 

128  ;  alkaline,  spectrum  of,  128. 
Hajmatoscope,  figure  of,  113. 

Hajmin,  129  ;    crystals,  figure  of,  129  ;  crystals, 

how  to  examine,  490. 
H?emochromogen,  125. 
Hasmocj'aniii,  occurrence  of,  143. 

Hajmoglobin,  117  ;  compounds  of,  124,  125  ;  con- 
ditions in  which  it  occurs,  119  ;  crvbtals,  how 
to  examine,  490  ;  occurrence  of,  123,  124  ;  per- 
centage composition  of,  118  ;  preparation  of. 
118,  119  ;  reduced,  119  ;  reduced,  spectrum  of, 
123  ;  synonyms  of,  118. 

Haller,  on  irritability  of  muscle,  400. 

Hallibcrtox's  researches  in  chemistry  of  muscle, 
501. 

Hallwachs,  on  hippuric  acid,  106. 

Haloid  derivatives,  49. 

Ham,  on  spermatozoa,  214,  215. 

Hamersten,  on  glycocholic  acid,  107. 

Hardening  in  microscopic  research,  268. 

Hartig,  on  deposition  of  carbonate  of  lime,  19. 

Haversian  canals  in  bone,  333  ;  how  to  examine, 
498  ;  systems  in  bone,  333. 

Heart,  how  to  examine  muscles  of,  493. 

Heat,  a  kind  of  energy,  12  ;  a  mode  of  motion, 
11;  effect  of ,  on  protoplasm,  290 ;  measurement 
of,  12  ;  production  of  by  muscle,  421-424 ;  re- 
lations of,  to  work,  12. 

Heideshain,  on  heat  production  in  muscle.  421. 
422. 

Hettzmaxx,  on  protoplasm,  289,  290. 

Heller,  on  indican  derivatives,  135. 

Helmholtz,  myograph  of,  390 ;  on  contraction  of 
muscle,  453 ;  on  energy,  11;  on  fermentation, 
179  ;  on  induction,  375,  376  ;  on  negative  varia- 
tion, 452. 

Helmoxt,  Van,  theory  of  life,  32. 

Hemicollin,  79. 

Hensen,  median  disc  of,  309. 

Hereditv,  definition  of,  30  ;  physiological  basis- 
of,  234-244. 

Hermann's  propositions  as  to  currents,  459 :. 
theory  of  muscle  currents,  456,  457,  458  ;  on 
currents  in  living  man,  459 ;  on  muscle  cur- 
rents, 457,  458. 

Hertwig,  on  polar  bodies,  227. 

Heterodromous  currents,  definition  of,  479. 

Hippocrates,  on  life,  32. 

Hippuric  acid,  56,  104,  105,  106 ;  crystals,  figure- 
of,  105  ;  origin  of,  105,  106  ;  tests  for,  10.5. 

Histohsematins,  137,  138. 

Histology,  history  of,  201-214  ;  reference  to,  2. 

Hoffmann's  test,  93  ;  on  fermentation,  179. 

Hofmeister,  on  collagen,  79. 

Holm,  on  hjematoidin,  129. 

Homodromous  currents,  definition  of,  479. 

Hoppe-Seyler,  analysis  of  nuclein,  78  ;  on  al- 
bumin, 71  ;  on  carbonic  oxide  bajmoglobin,  124-, 
on  chemical  ferments,  186  ;  on  choroiihyll,  23  ; 


510 


jyoEA-. 


on  cholalic  acid,  107,  108  ;  oti  composition  of 
proteids,  5S  ;  on  constitution  of  hiemochronio- 
gen,  Vi:> ;  on  fermcnfcitioii,  1S2,  is:i ;  on  gelatin, 
7;)  ;  on  liainiatoporph.vrin,  127  ;  on  methsenio- 
globin,  12(5 ;  on  naphtliylamine,  100  ;  on  oxida- 
tion, 171 ;  on  protagon,  82  ;  on  proteids,  (J-l ;  on 
the  spectrum  of  blood,  110  ;  on  totronerytbrin, 
144. 

noKMA.N>f,  on  endosmotic  equivalent,  34it. 

lIowsHir,  lacuna;  of,  341. 

Hyaline  cartilage,  328,  320 ;  matrix  of,  323,  324. 

Hydrobilirubin,  134. 

Hydrocarbon,  derivatives  of,  4(1,  47  ;  formuhc  of. 
4(3 ;  series  of,  40,  47. 

Hydrochloric  acid,  in  the  body,  42. 

Hydrogen,  occin-rence  of  in  body,  KiO,  170. 

Hydroxyl,  IG. 

Hygroplasm,  235. 

Hypoblast,    formation    of     24J-247  ;    structures 
derived  from,  252. 

Hypoxanthin,  103. 

I 

latro-chemists,  32. 

latro-mathematicians,  32. 

Idioplasm,  235. 

Imbibition,  molecular,  in  tissues,  352. 

Idio-muscular  contraction,  419. 

Inclination  currents  in  niuscle,  448. 

Indioan,  derivatives  of,  135;  characters  of,  135, 
130. 

Indigo  blue,  spectrum  of,  13(3. 

Indol,  56,  lOCf,  110. 

Induction  coils,  373-37(3 ;  electrical,  373,  374. 

Inductorium  of  Du  Bois-Reymond,  373,  374. 

Imbibition,  capillary,  in  tissues,  352. 

Injection  in  microscopic  research,  273. 

Inorganic  constituents  of  the  body,   34 ;    com- 
pounds of  the  body,  35. 

Inosite  crystals,  figure  of,  157  ;  characters  of,  157, 
158  ;  origin  of,  158. 

Inosinic  acid,  5(3,  lOii. 

Intercellular  substances,  322,  323,  324. 

Intestinal  muscle  fibre,  500. 

Intussusception,  17. 

Investigation  of    fresh  objects    in    microscopic 
reseai-ch,  270,  277,  278. 

Involuntary  muscle,  how  to  j^repare,  500. 

Iron  in  the  body,  42. 

Irritability    of    cells,   205 ;    of  muscle,   400-405 ; 
nature  of,  403  ;  variations  of,  403,  404. 

Isocholesterin,  147. 

Isolating  fluids  for  different  tissues,  265,  260. 

Isomerism,  definition  of,  48. 

Isotropic  substance  of  muscle  fibre,  307. 


.Jacobt,  on  fecundation,  223. 
.Tenkin,  on  electricity,  373. 
.Tolly,  on  endosmatic  equivalents,  349. 
Joule,  on  heat,  11 ;  dynamical  equivalent  of,  12  ; 
experiments  of,  12. 

K 
Karyokinesis,  212,  213^  297  ;  method  of  demon- 
strating, 487. 
Karyosteno.sis,  212,  213 ;  nature  of,  290,  297. 


Kkhui.k,  on  amyloid  matter,  77  ;  on  carbon  pro- 
perties, 45  ;  on  constitution  of  benzol,  51  ;  oji 
organic  chemistry,  44. 

Kephalins,  83. 

Keratin,  55,  80  ;  chemical  composition  of,  SI. 

Ketones,  formuhe  of,  4(i. 

Key,  l)u  Bois-Reymond's  friction,  376,  377. 

Kinoline,  80. 

Kleix,  on  temperature  in  fermentation,  192. 

Kniriem,  on  ori^'in  of  urea,  87. 

IvoLUEtrn;ii,  on  fecundation,  223. 

Kocii,  on  succinic  acid,  107. 

KoLLiKKR,  on  heredity,  238;  on  spcrmatin,  78; 
on  origin  of  spermatozoa,  215,  216. 

Kraus,  on  formation  of  starch,  23. 

Krause's  membrane,  300. 

Kroxf.ckek,  on  genesis  of  tetanus,  417;  on 
muscular  fatigue,  430. 

Krhkenbero,  on  biliverdin,  131 ;  on  lipochromea, 
139. 

KiJHNE,  on  chromophanes,  140;  on  hippuric  acid, 
106  ;  on  irritability  of  muscle,  400  ;  on  motor 
end  plates,  359  ;  on  indol,  110. 

KiiLZ,  on  inosite,  157. 

I; 

Lactic  acid,  105. 

Lactose,  158,  1.59. 

Lasvulose,  157. 

Lamarck,  definition  of  life,  31. 

Laxdois,  on  rapidity  of  contraction  of  muscle, 
412. 

Langlev,  on  vital  energy,  24. 

Lardacein,  77. 

Latent  stimulation,  period  of,  in  muscle  contrac- 
tion, 400,  407. 

Latschinoff,  on  cholesterin,  147. 

Laxkester,  on  peutacrinin,  144. 

Laurence,  definition  of  life,  31. 

Lavoisier,  on  fermentation,  176. 

Lecithin,  55,  83  ;  characters  of,  82,  83. 

Leclanche's  voltaic  element,  370,  371. 

Le  Coxte,  on  vital  energy,  21. 

Leedweniioek,  on  fermentation,  177. 

Legumin,  75. 

Length,  measurement  of,  5. 

Leucin,  16,  55;  characters  of,  91,  02;  crystals, 
figure  of,  92. 

Leucippds,  atomic  theory  of,  8. 

Leucocytes,  299  ;  in  frog's  blood,  figure  of,  295 ; 
mode  of  examining,  489. 

Leyden,  on  production  of  heat  in  muscle,  423. 

Lieberkuhn,  on  albumin,  62. 

Liebio,  on  fermentation,  177,  178. 

LiEBREiCH,  on  protagon,  82. 

Life,  old  theories  of,  32  ;  theories  of,  31  ;  pheno- 
mena of,  in  living  cell,  33. 

Ligament.s,  structure  of,  328. 

Light,  influence  of,  in  fermentation,  193  ;  polariz- 
ation of,  66,  (37  ;  a  source  of  vital  energy,  24. 

Liminal  intensity  of  stimulus,  424. 

Lipochromes,  139. 

Liquor  sanguinis,  74. 

Lime  salts,  quantity  in  the  body,  40  ;  physiology 
of,  41. 


INDEX. 


511 


Living  things,  essential  characters  of,  31. 

Liquor  folliculi,  222. 

Locke,  John,  on  heat,  11. 

LoEw,  on  chemical  actions  of  protoplasm,  GO  ;  on 
proteids,  03. 

Lucre's  test  for  hippuric  acid,  105. 

LuDWiG,  on  endosmosis,  349. 

Luteins,  13ft. 

Lymphoid  tissue,  how  to  examine,  -tOiJ. 
M 

M'Kendrick,  on  temperature  in  fermentation, 
193. 

MacMustn,  on  hiliverdin,  131 ;  on  choloh»matin 
132;  on  chlorocruorin,  143;  on  chlorophj'll 
143 ;  on  echinochrome,  143 ;  on  hsematopor 
phyrin,  127,  128;  on  histohaimatins,  137,  13S 
on  myohiematins,  13?,  139  ;  on  oxy haemoglobin 
120,  121,  123 ;  on  pentacriuin,  144 ;  on  physio 
logical  spectra,  117  ;  on  spectrum  of  hasmatin 
127;  on  spectrum  of  hsemochromogen,  125  ;  on 
spectrum  of  indigo  blue,  136 ;  on  spectrum  of 
methremoglobin,  126 ;  on  spectrum  of  urabiliu, 
135;  on  stercobilin,  136. 

Magellan's  meteorograph,  383. 

Magnesium  salts  in  the  body,  41. 

Malapterurus  electricus,  46S-470. 

Maltose,  159. 

Mannite,  157. 

Mann  itose,  157. 

Marchand,  on  hippuric  acid,  105. 

Maret,  myograph  of,  392,  393 ;  on  elasticity  of 
muscle,  399 ;  on  genesis  of  tetanus,  417 ;  on 
wave  of  muscular  contraction,  412,  413 ;  tam- 
bours of,  394-397. 

Marie-Davt's  voltaic  element,  371. 

Marrow,  elements  of  334,  335  ;  of  bone,  333,  334  ; 
how  to  examine,  498. 

Marrow  sheath,  how  to  examine,  493. 

Marshall  Ward,  on  organized  ferments,  1S9. 

Mass,  measurement  of,  5. 

Matteucci,  discoveries  of,  440 ;  induced  contrac- 
tion of,  452,  453. 

Matter,  and  Energy,  permanence  of,  4  ;  circula- 
tion of,  16;  colloidal  condition  of,  13;  inde- 
structibility of,  4 ;  its  condition  in  living  things, 
9  ;  its  importance  in  vital  actions,  9 ;  quantita- 
tive estimation  of,  5. 

ilatrix  of  bone,  324  ;  of  hyaline  cai'tilage,  323, 
324. 

Mayer,  on  heat,  12  ;  on  vital  energy,  20. 

Matow,  theory  of  life,  32. 

Mechanical  stimuli  in  muscular  contraction,  419. 

Medicus,  on  constitution  of  uric  acid,  98. 

Medullated  nerve  fibres,  315. 

Medullary,  folds,  formation  of,  248 ;  plates,  for- 
mation of,  248  ;  ridge,  figures  of  formation  of, 
247. 

Mrissner,  on  creatinin,  95;  on  hippuric  acid, 
105,  106;  on  succinic  acid,  167. 

Melanin,  142. 

Melsens,  on  temperature  in  fermentation,  192. 

Membrana  granulosa,  222. 

Mbrejkowski,  on  tetronerythrin,  144. 

Merkel,  on  origin  of  spermatozoa,  216. 

Mesoblast,  development  of  in  amphioxus,  250  ; 
figures  of  deveL  ipment  of  249 ;  formation  of, 
248 ;  origin  of,  248,  249 ;  structures  derived 
from,  251,  252. 


Metabolic  processes  in  animals,  26. 

Metabolism,  17;  constructive,  22;  definition  of, 
294  ;  destructive,  22. 

Metaplastic  type  of  ossification,  340. 

Metastasis,  definition  of,  294. 

Meteorograph,  Magellan's,  383. 

Methsemoglobin,  125,  126. 

Methane,  45 ;  substitution  derivatives  of,  45. 

Metric  system,  5. 

Metronome,  in  study  of  muscle,  377. 

MicellcO,  236. 

Microscope,  the,  252-256 ;  description  of,  253-257  ; 
figures  of,  254,  255 ;  mode  of  using,  257,  258, 
259. 

Microscopic  research,  decalcification  in,  268,  269  ; 
methods  of,  257-278  ;  preparation  of  sections  in, 
269,  270;  staining  in,  270,  271,  272,  273;  acces- 
sory appliances  to,  259,  260;  dissection  of 
animals  for,  264  ;  fixing  in,  260,  267,  268  ;  hard- 
ening in,  268  ;  injection  in,  273  ;  investigation 
of  fresh  objects  in,  270,  277,  278 ;  isolation  in, 
205,  206  ;  mounting  of  preparations  in,  273,  274, 
275,  276  ;  nature  of  material  for,  263,  204 ;  pre- 
servation of  preparations  in,  273,  274,  275,  276, 
278;  reagents  required  in,  260,  261,  262,  263. 

Mierospectroscope,  figures  of,  114,  115. 

Micrococcus  luteus,  192. 

Microtomes,  278-287  ;  figure  of,  283  ;  rocking,  285 ; 
Rutherford's,  279  ;  Rivet's,  284 ;  Roy's,  282  ;  ice 
freezing,  280,  281. 

MiEscHER,  analysis  of  nucleln,  78. 

Migrations  of  cells,  295. 

Millon's  reaction,  64. 

Mineral  matters  present  in  the  body,  37. 

Mineral  matters,  table  of,  in  animal  solids,  37. 

Mineral  matters,  table  of,  in  animal  fluids,  37. 

Mitscherlich,  on  fermentation,  179. 

MoHL,  Von,  on  protoi^lasm,  14. 

Montgomery,  on  formation  of  cells,  19. 

Molecular  change,  14  ;  instability,  16 ;  pheno- 
mena, occurrence  of,  in  living  things,  8. 

MoLESCfiOTT,  on  percentage  of  fat  in  the  body,  150. 

Moore's  test  for  glucose,  152. 

MoROCHOwiTZ,  on  chondrin,  8u. 

Morphine,  89. 

Morphology,  reference  to,  3. 

MosELEY,  on  aplysiopurpurin,  145  ;  on  crus- 
taceorubin,  144. 

Motion,  ciliary,  nature  of,  821,  322. 

Motor  end-plates  in  muscle,  358,  359  ;  analogy 
with  electrical  organ,  484. 

Mounting  of  preparations  in  microscopic  research, 
273,  274,  27.5,  276. 

Movement  of  cells,  295  ;  transmission  of,  in  study 
of  muscle,  394,  397. 

Mucin,  55,  77,  78  ;  chemical  composition  of,  81  ; 
chemical  reactions  of,  81. 

Mucous  connective  tissue,  325  ;  how  to  demon- 
strate, 495. 

Mulder,  on  composition  of  proteids,  58. 

Mulder-Neubauer,  test  for  glucose,  153. 

Multipolar  nerve  cells,  313. 

MuNK,  on  creatinin,  95  ;  on  origin  of  urea,  87. 

Murexide  test,  for  uric  acid,  101. 

Muscle,  atrophy  of,  433,  434,  435. 

Muscle  and  tendon,  how  to  study  position  of,  500; 
blood  of,  357  ;  cells,  305-313  ;  chemistry  of,  501 ; 


512 


INDEX. 


coliesion  of,  397,  3PS  ;  coniiectioiiof  with  tendon, 

357  ;  consistence  of.  3ii7  ;  contraction,  wiive 
propagation,  412-il4  ;  contraction,  remainder 
of,  412  ;  current-',  determination  of  amount  of, 
449-451  ;  currents,  direction  of,  448  ;  duration 
of  contraction  of,  412  ;  current  negative  varia- 
tion of,  452  ;  currents,  tlieories  of,  454-458  ; 
elasticity  of,  398,  399,  400  ;  electric  apparatus 
in  study  of,  3(i3-3Sl  ;  electrical  phenomena  of, 
430-459  ;  ferment,  501,  502  ;  fibre,  chemical  con- 
stitution of,  300-303;  examination  of  by  polarized 
light,  308 ;  formation  of,  357 ;  gi-owth  of,  433, 434, 
435  ;  how  to  demonstrate  nerve  endings  in,  500 ; 
how  to  demonstrate  lamified  fibres,  492  ;  how  to 
prepai'e  for  histological  purposes,  492  ;  inclina- 
tion currents  in,  448  ;  involuntary  form  of,  357, 

358  ;  involuntary,  how  to  examine,  491  ;  irrita- 
bility of,  4110-405  ;  latent  period  of,  503 ;  lymph 
vessels  of,  357;  measurement  of  work  done  by, 
425,  420;  metabolism  in,  430-432  ;  mode  of  pre- 
paring for  study  of  structure  of,  500  ;  motor 
end-plate  of,  358,  359  ;  non-striated  form  of,  357, 
35S  ;  nutritive  changes  in,  430-432  ;  period  of 
contraction  of,  407 ;  period  of  relaxation  of,  407 ; 
phenomena  of  contraction  of,  405-414;  physical 
properties  of,  397-400;  plasma,  300, 301 ;  plasma, 
Halliburton's  method  of  analyzing,  502  ;  pro- 
duction of  heat  by,  421-424  ;  rapidity  of  contrac- 
tion of,  412  ;  recording  of  single  contraction  of, 
408,  409;  relations  of,  to  nerves,  350-SOO  ;  serum, 
constitution  of,  301,  302  ;  soiind,  427,  428  ;  static 
force  of,  42(),  427  ;  striated,  how  to  examine, 
492  ;  structure  of,  350-3ii0  ;  summarj'  of  pheno- 
mena of  living,  400,  401  ;  telegi'aph,  401  ;  ter- 
mination of  nerve  in,  358  ;  tracings  of  contrac- 
tions of,  411  ;  work  done  by,  424-427. 

JIuscular  contraction,  amount  of,  405,  412,  425  ; 
dynamical,  29  ;  modes  of  exciting.  418-421  ; 
observation  of,  405,  400  ;  fatigue,  phenomena 
of,  428-430  ;  fibre,  properties  of  non-striated, 
435,  436  ;  fibres,  figures  of,  309,  310,  311,  312  ; 
smooth,  305  ;  transversely  striated,  305-313. 

Jlyeo-protein,  190. 

Myelins,  S3. 

Myeloplaxes,  nature  of,  334. 

Myo-albumose,  502. 

Myo-epithelial  cells,  35C. 

Myoglobulin,  501. 

Myograph,  the  pendulum,  408,  409. 

Myographs,  390,  391,  392,  393  ;  figure  of,  28. 

Myohajmatin,  138,  139. 

Myosin,  74,  301. 

Mvosinogen,  501. 

N 

Naegeli,  on  hereditj',  235  ;  micellar  theory  of,  13 ; 
on  schizomj'cetes,  188. 

Naphthylaraine,  50,  109. 

Narceine,  89. 

Narcotine,  89. 

N.-^ssE,  on  composition  of  proteids,  58. 

Nef.f's  interrupter,  373,  374. 

Negative  variation  in  muscle  current,  400,  452. 

Xen'ckt,  on  indol,  110. 

Neox)lastic  tyiae  of  ossification,  340. 

Xerve  cells,  313,  'oU  ;  how  to  examine,  493. 

Xerve  endings  in  muscle,  how  to  prepare,  500. 

Xerve  fibres,  314-317  ;  figure  of,  315,  310  ;  how  to 
examine,  493  ;  medullated,  definition  of,  313  ; 
how  to  prepare  for  histological  purposes,  493  ; 
terminations  in  muscle,  358  ;  muscle  prepara- 
tion, 27,  28,  401  ;  nou-medullated,  how  to  pre- 
pare for  histological  purposes,  494  ;  action  of 
silver  nitrate  on,  494. 


Neural  canal,  formation  of,  245,  248. 

Neurilemma,  nature  of,  31G. 

Xcurin,  82,  83. 

Xewtox,  atomic  theory  of,  8. 

Nicotine,  89. 

Nitric-oxide  luemoglobin,  124,  125. 

Nitrogen,  presence  of  in  the  body,  168. 

Nitrogenous  acids,  50,  97  ;  bodies,  formation  of, 
23  ;  bodies  without  oxygen,  56  ;  fatty  sub- 
stances, 81  ;  substances,  55  ;  substances,  with- 
out oxygen,  109. 

Nitro-glyceriue,  composition  of,  10  ;  instability 
of,  10. 

NoBlLi,  galvanometer  of,  439,  440. 

NoF-UoRFKEL,  thcrmo-electric  batteiy,  372. 

Xon-medullated  nerve  fibres,  317. 

Xon-nitrogenous  oi-ganic  acids,  101. 

Xon-nitrogenous  substances,  57,  140. 

Non-polarizable  electrodes,  380. 

Non-striated  muscle,  how  to  prepare,  500. 

Notochord,  formation  of,  248. 

Nuclear  division,  diagram  of,  228. 

Nuclei,  method  of  demonstrating,  487. 

Nuclein,  55,  78. 

Nutrition  of  bone.  340  ;  of  cartilage,  340  ;  of  con- 
nective tissue,  340. 

O 

Odlinc;,  on  relations  of  uric  acid,  100. 

Oersted,  discoveries  of,  439. 

Ohm's  law  in  electricity,  365. 

Olefiant  gas  and  derivatives,  47. 

Oleic  acid,  168. 

Oleic  acid  series,  57. 

Olein,  149. 

Ontogeny,  definition  of,  3. 

OrPLER,  on  creatinln,  95. 

Ord,  'William  Muller,  on  the  influence  of 
colloids  on  crystalline  form,  17  ;  on  fonnatiou 
of  bone,  etc.,  19. 

Organ  current  of  electrical  fishes,  478,  479. 

Organic  compounds  of  the  body,  35,  55  ;  com- 
pounds, classification  of,  55  ;  composition  of, 
44  ;  constitution  of,  50  ;  constituents  of  the 
body,  43  ;  material,  formation  of,  in  ijlants,  22. 

Organisms,  life  cycles  of,  30. 

Organs,  definition  of,  292. 

Ossification,  336-341 ;  mode  of  preparing  tissues 
for  study  of,  499. 

Osmosis,  causes  of,  .Sol,  352;  in  relation  to 
tissues,  347-353. 

Osteoblasts,  nature  of,  339. 

Osteoclasts,  nature  of,  341. 

Ova.  discoveries  of,  219  ;  figures  of,  before  and 
after  fecundation,  231  ;  origin  of,  221,  222 ; 
female  elements,  219 ;  mode  of  examining 
fresh,  488. 

Ovaries,  structure  of,  220,  221 ;  examination  of, 
488  ;  figures  of  transverse  section,  220,  221. 

Ovum,  17 ;  development  of,  222 ;  figure  of,  220 ; 

structure  of,  219. 
Oxalic  acid,  100,  107  ;  origin  of,  in  the  bod}-,  107. 
Oxalic  acid  series,  57,  100. 
Oxaluric  acid,  55,  104,  88. 
Oxidation,  in  the  living  organism,  170,  171,  172. 


INDEX. 


513 


Oxyhsemoglobin,  120, 121, 122  ;  spectruri  analysis 

of,  120,  121,  122,  123. 
Oxyhsemoglobin  crystals,  figure  of,  119. 
Oxygen,  presence  of,  in  the  body,  168. 
Ozone,  influence  of,  in  fermentation,  194. 

P 
P.acini,  on  gymnotus  electricus,  46.5,  466,  467 ;  on 

Torpedo  Galvani,  462. 
Palmitic  acid,  163. 
Palmitin,  149. 
Papaverine,  89. 
Paracelsus,  theory  of  life,  32. 
ParaflSn,  embedding  of  tissues,  279 ;  infiltration  iu 

section  cutting,  282,  283,  284,  285,  286,  287. 
Paraffins,  general  formulae  of,  46  ;  properties  of, 

46. 
Paraglobulin,  74. 
Paralbumin,  55,  76. 
Paramyosinogen,  501. 
Paranucleolus,  225. 

Pasteur,  on  fermentation,  176,  ISO,  181. 
Pathology,  relation  to  physiology,  3. 
Pendulum  myograph,  408,  409. 
Pentacrinin,  occurrence  of,  144. 
Peptones,  55,  75,  76. 
Perichondrial  ossification,  337,  339,  340. 
Perichondrium,  structure  of,  331. 
Periosteum,  structure  of,  335,  336. 
Pettenkofer's  test  for  bile  acids,  108. 
Pfluger,   on   composition  of    proteids,   59 ;    on 

heredity,  236  ;  on  oxidation,  171. 
Phenol,  16  ;  occurrence  of,  149. 
Phosphates  in  the  body,  42. 
Phosphoglyceric  acid,  55,  82. 
Phylogeny,  definition  of,  3. 

Physical  properties  of  connective  tissues,  343, 
344,  345  ;  properties  of  muscle,  397-400  ;  theory 
of  muscle  currents,  455,  456. 
Physics,  relation  to  x)hysiology,  3. 
Physiological  processes  in  plants,  22. 
Physiology,  definition  of,  1 ;  means  of  investigat- 
ing, 4  ;  object  of,  4  ;  source  of  its  facts,  2. 
PiCARD,  estimation  of  iron  in  spleen,  42. 
Picric  acid,  composition  of,  16 ;  test  for  glucose, 

153. 
PicoT,  on  physiological  action  of  water,  36. 
PiCTET,  on  temperature  in  fermentation,  192. 
Pigments,  56,  111 ;  of  bile,  130;  of  blood,  56;  of 
the  fajces,  136  ;  of  the  tissues,  137  ;  of  urine, 
134 ;   physiological   significance    of,  145,  146  ; 
spectroscopic  detection  of,  111,  112. 
PioTRowsKi's  reaction,  64. 
Piria's  test,  93. 
Plasm  cells,  496. 
Ploesz,  on  glycerine,  148. 
Pohl's  commutator,  378,  379. 
Polar  body  extruding,  figure  of,  227 ;  extrusion 
of,  225-230  ;  extrusion,  discoveries  of,  226  ;  for- 
mation of,  225-230. 
Polarimeters,  68,  70. 

Polarizable  electrodes  of  Du  Bois-Reymond,  379 
380. 

Polarization,  66  ;  currents  in  torpedo,  479,  480. 

Polymerism,  definition  of,  48. 


Polymerization,  23. 

Porret's  experiment,  397. 

Potassium  chloride,  quantity  in  the  body,  38. 

Potassium  salts  in  the  blood,  39. 

Potential,  electrical,  363. 

Preparation  of  organs  in  research,  263-278  ;  of 
tissues  in  research,  263-278. 

Preservation  of  preparations  in  microscopic  re- 
search, 273,  274,  275,  276,  278. 

Pressure,  influence  of,  in  fermentation,  194. 

Prevost,  on  fecundation,  223. 

Preyer,  on  carbonic-oxide  hsemoglobin,  124;  on 
hemoglobin,  118;  on  hsematoidin,  129;  on 
estimation  of  oxyhsemoglobin,  122  ;  on  oxy- 
hEemoglobin,  120,  122. 

Primary  bones,  development  of,  337-340. 

Primitive  groove,  origin  of,  248  ;  streak,  origin 
of,  248. 

Products  of  oxidized  bile  pigment,  133. 

Pronucleus,  female,  231 ;  male,  231. 

Properties  of  non-striated  muscle,  435,  436. 

Propionic  acid,  163. 

Protagon,  82  ;  formation  of  processes  of,  19  ;  pro- 
perties of,  19. 

Proteids,  55 ;  animal  and  vegetable,  table  of,  71 ; 
living,  action  of,  63 ;  chemical  action  of,  61 ; 
chemical,  57,  64;  decomposition  of,  59;  phy- 
sical characters  of,  64 ;  physiological  characters 
of,  71 ;  quantities  of,  in  tissues  and  fluids,  71 ; 
special,  72  ;  synthesis  of,  61. 

Proteins,  55,  75. 

Prothyalosome,  229. 

Protoplasm,  14,  288-292  ;  effects  of  external  agents 
upon,  290,  291,  292  ;  source  of  vital  energy  of. 
24. 
Proximate  principles,  35  ;  characteristics  of,  in 

living  things,  15  ;  definition  of,  15. 
Pseudo-cerebrin,  S3. 
Pyrrol,  56,  111. 


Quinine, 


R 


Rabl,  on  karyokinesis,  228. 

Radicles,  organic,  table  of,  162. 

Raia  batis,  electrical  organ  of,  470,  471. 

Eainey,  experiments  of,  17;  on  formation  of 
shells,  bone,  etc.,  17  ;  on  deposition  of  car- 
bonate of  lime  in  presence  of  a  viscid  substance, 
IS  ;  on  formation  of  shells,  bone,  etc.,  IS. 

Rajewski,  on  alcohol,  146. 

Ranvier's  cells  in  tendon,  327 ;  nodes  of,  in 
nerve,  316  ;  on  Torpedo  Galvani,  464. 

Ray  Lankester,  on  chlorocruorin,  143;  on  chloro- 
phyll, 142,  143. 

Reactions,  chemical,  in  the  living  organism,  170. 

Reagents  required  in  microscopic  research,  261, 
262,  263. 

Recording  cylinder  in  measuring  time,  384,  385. 

Reduction,  chemical,  in  the  living  organism,  172, 
173. 

Reid,  on  muscular  irritability,  403. 

Relaxation  of  muscle,  period  of,  407. 

Remak,  band  of,  315. 

Renson,  on  origin  of  spermatozoa,  217. 

Reproduction  of  cells,  296,  297. 


2  K 


ol-t 


INDEX. 


Residual  contractions  of  muscle,  407;  contraction, 
as  a  function  of  muscle,  4'25. 

Reticular  tissue,  structure  of,  32S. 

Retina,  how  to  demonstrate  pigment  cells  of, 
491. 

Reymosd,  see  Du  Bois-Reymond. 

Rheochord  of  Du  Bois-Reymond,  4ol,  45.;. 

Rheotome,  409. 

Rhodophane,  141. 

Rhodopsin,  spectrum  of,  141. 

Richardson,  on  physiological  action  of  water,  3(i. 

Rigor  mortis,  phenomena  of,  432,  433. 

RiTTER,  on  blue  pigment  of  bile,  133  ;  on  decom- 
position of  urea,  40. 

Roberts,  Sir  William,  estimation  of  glucose,  15  J. 

Rosenthal,  on  muscular  irritability,  402. 

RuMFORD,  on  he.at,  11. 

Rutherford,  on  electric  stimuU,  418;  on  growth 
of  muscle,  434  ;  microtomes  of,  279,  280,  281. 


Saccharimeter,  estimation  of  glucose  by,  153,  154, 

155 ;  figure  of,  (iS  ;  Soleil's,  (59. 
Saccharomycetes  cerevisiae,  185. 
Saccharoses,  158. 

Sachs,  on  electric  shocks  of  gymnotus,  473,  474. 
St.  George,  on  origin  of  sjiermatozoa,  217. 

Salkowski,  on  cholesterin,  147;  on  oriarin  of 
urea,  86,  87  ;  on  origin  of  uric  acid,  103  ;  on 
urine,  40. 

Salts,  metallic,  of  organic  acids,  49  ;  of  organic 
acids  in  body,  56. 

Sarcin,  103. 

Sarcolactic  acid,  165. 

Sarcolemma,  nature  of,  306. 

Sarcosin,  56,  97. 

Sarcous  elements  of  muscle,  307. 

Savi,  on  Torpedo  Galvani,  462. 

Sea  urchin,  division  in  egg  of,  233,  234. 

Secondary  bones,  development  of,  341. 

Secreting  epithelial  cells,  figure  of,  297  ;  gland 
cells,  figure  of,  298. 

Secretion,  cellular,  nature  of,  295 ;  in  cells,  pheno- 
mena of,  297,  298. 

Section  cutting,  celloidin  in,  287  ;  ether,  freezing 
in,  282 ;  paraffin,  infiltration  in,  2S2,  283,  284, 
285,  286,  287. 

.•Sections,  preparation  of,  269,  270. 

Segmentation  and  development  of  fowl's  egg, 
246,  252  ;  cavity,  f onnation  of,  244. 

Semiglutin,  79. 

Seminal  stains  on  linen,  mode  of  examining,  488. 

Sensibility  of  bone,  346 ;  of  cartilage,  346 ;  of 
connective  tissue,  346. 

Serial  section  cutting,  278-287. 

Sertoli,  on  origin  of  spermatozoa,  216,  217. 

SCHAFER,  on  cellulose,  160,  161. 

Schafer,  E.  a.,  on  muscular  fibre,  310. 

Scherer's  test  for  inosite,  158. 

ScHiFF,  on  mechanical  stimuli,  419. 

Schizomycetes,  cultivation  of,  194-200  ;  develop- 
ment, effects  of  external  influences  in,  191, 192, 
193,  194 ;  figure  of,  188 ;  multiplication  of,  190. 

Schmidt,  on  fermentation,  176. 


Schmiedeberg,  on  hippurio  acid,  106 ;  on  origin 

of  urea,  87. 
ScHONBKiN",  on  oxidation,  171. 
Schorlemmer,  on    carbon    compounds,  54;    on 

organic  compounds,  44. 
ScHRtEDER,  on  fermentation,  179. 
ScHULZE,  on  cholesterin,  147. 
Scuoltzes,  on  origin  of  urea,  86. 
ScHUNCK,  on  indican  derivatives,  135. 

Schutzenbkroer,  analysis  of  yeast  by,  177  ;  on 
naphthylamine,  109  ;  on  proteids,  58. 

Schwann',  on  fermentation,  177, 178,  179  ;  white 
substance  of,  in  nerve,  315. 

Sharpey,  fibres  of,  336 ;  fibres,  how  to  demon- 
strate, 498. 

Shells,  formation  of,  17. 

Shepard,  on  hippuric  acid,  105,  106. 

Signal  of  Deprez,  389. 

Silver  nitrate,  action  on  nerves  of,  494. 

Simony,  on  bilif  uscin,  132. 

Sinapine,  89. 

Skatol,  56,  111. 

Smee's  voltaic  element,  371. 

Sodium  chloride,  quantity  of  in  the  body,  38 ; 

salts  of  in  the  blood,  39. 
Soleil's  saccharimeter,  69. 
Somatopleure,  origin  of,  249. 
SoRBY,  on  aphidein,  144,  145. 
Spallaszani,  on  fecundation,  223  ;  on  oxidation, 

171. 
Spectropolarimeter,  figure  of,  154. 
Spectroscope,    direct    vision,    arrangement     of 

prisms  in,  114  ;  arrangement  for  detection  of 

pigments  by,  figure  of,  112. 
Spencer,  Herbert,  reference  to,  21 ;  definition  of 

life  by,  32. 
Spermatoblasts,  examination  of,  488. 
Spermatin,  55,  78. 

Spermatogenesis,  figures  of,  216,  217. 
Spermatozoa,  217,  218,  219;  discoverers  of,  214, 

215;  nature  of,  214-219;   development  of,  215, 

216,  217;  figures  of,  218,  219;   influence  of  on 

ovum,  223,  224  ;  living,  examination  of,  488. 

Splanchnopleure,  origin  of,  249,  250. 
Spinal  cells  in  connective  tissue,  495. 
Staedeler,  on  bilihumin,  133  ;  on  biliprasin,  132 ; 

hajmatoidin,  129  ;  on  phenol,  149. 
Stahl,  theory  of  life  by,  32  ;  on  fermentation, 

179. 
Staining,  diffusive,  271 ;  fluids,  270,  271,  272,  273 ; 

in  mass,   271,   272 ;    in   microscopic  research, 

270, 271, 272, 273 ;  of  chromatin,  271 ;  of  nucleus, 

270,  271. 
Starch,  159 ;  formation  of,  23  ;  tests  for,  159. 
Stearic  acid,  163. 
Stearin,  149. 
Stercobilin,  136,  137  ;  spectrum,  analysis  of,  136, 

137. 
Stereoplasm,  235. 
Stimulus,  contraction  as  a  function  of,  424,  425  ; 

liminal  intensity  of,  424. 
Stirling,  W.,  on  genesis  of  tetanus,  417. 
Stokes,  on  the  spectrum  of  blood,  116,  117. 
Stokvis,  on  product  of  oxidized  bile  pigment, 

133,  134. 


INDEX. 


515 


storage  cell,  electrical,  373. 

Strasburger,  on  heredity,  23T,  238,  239  ;  on  im- 
bibition, 13  ;  on  polar  bodies,  225. 

Strassburg's  test  for  bile  acids,  108. 

Structure,  physical  of  living  things,  13. 

Strychnine,  89. 

Substantia  compacta  of  bone,  333  ;  spongiosa  of 
bone,  332. 

Succinic  acid,  107  ;  origin  of,  167. 

Sucroses,  57. 

Sulphates  in  the  body,  43. 

Sulphocyanic  acid,  56,  97. 

Sulphuretted  hydrogen,  170. 

Syntonin,  75. 

Synthesis,  in  the  living  organism,  17-1.  175. 


Tait,  on  atomic  theory,  S;  on  energy,  11  ;  on  re- 
cent advances  in  xjliysical  science,  10. 

Tambours,  Marey's,  394-397. 

Taurin,  56,  96  ;  crystals,  figure  of,  96. 

Taurocholate  of  sodium,  107. 

Taurocholic  acid,  56,  107. 

Telephone  in  animal  electricity,  445,  446. 

Temperature,  influence  of,  in  fermentation,  191, 
192,  193. 

Tendon,  how  to  examine,  496  ;  structure  of,  326, 
327. 

Tension,  in  production  of  heat  in  muscle,  422. 

Testis,  figure  of,  section  of,  215 ;  histological 
examination  of,  4S7,  488. 

Tetanus,  curve  of,  415  ;  genesis  of,  414-418 ; 
muscular  nature  of,  414. 

Tetronerythrin,  144. 

Thebaine,  89. 

Theca  f  olliculi,  222. 

Theine,  89. 

Theobromine,  89. 

Thermal  stimuli  in  muscular  contraction,  419. 

Thermo-electric  battery,  372. 

Thomson,  Sir  William,  galvanometer  of,  442  ; 
vortex  atom,  hypothesis  of,  9. 

Thudichum,  on  luteins,  139;  on  phosphorized 
bodies,  83  ;  on  urine  pigments,  134 ;  on 
uromelanin,  136  ;  on  urochrom,  136 ;  on  crypto- 
phanio  acid,  106. 

Time,  contraction  as  a  function  of,  425 ;  measure- 
ment of,  in  study  of  muscle,  384,  389 ;  measure- 
ment of,  5. 

Tissues,  complex,  definition  of,  292 ;  origin  of, 
214-234 ;  the  physiology  of,  201 ;  pigments  of, 
137  ;  simple,  definition  of,  292. 

Tone-inductorium  in  tetanus,  417. 

-Tonicity,  muscular,  400. 

Torpedo  Galvani,  -162-465;  mode  of  electrical 
action  of,  481 ;  secondary  discharges  from,  483. 

Transmission  of  movement  in  muscle  study,  394, 
397. 

Treviranus,  definition  of  life  by,  31. 

Tributyrin,  151. 

Tricaprin,  151. 

Tricaproin,  151. 

Tricaprylin,  151. 

Trimethylamine,  56,  109. 

Trimargarin,  151. 


Triolein,  151. 

Tripalmitin,  150. 

Tristearin,  150,  151. 

Trivalerin,  151. 

Trommer's  test  for  glucose,  152. 

TubuU  seminiferi,  histological  examination  of, 

487  ;  figure  of,  215,  216. 
Tunica  granidosa,  222. 
Turacin,  144. 

Twitch,  muscular,  nature  of,  414. 
TrNDALL,  on  temperature  in  fermentation,  193. 
TjTian  purple,  occurrence  of,  145. 
Tyrosin,  16,  55,  93  ;  crystals,  figure  of,  93 ;  tests 


for,  93. 


U 


Urate  (acid)  of  ammonia,  101 ;    of  lime,  101 ;  of 

lithium,  101 ;    of  potassium,  101 ;   of  sodium, 

101. 
Urates,  101. 
Urea,  16,  55,  85  ;    constitution  of,  84  ;   crystals, 

figure  of,  84  ;  fermentation  of,  85  ;   nitrate  of, 

crystals   of,   figure  of,  85  ;   occurrence  of,  84 ; 

origin  of,  86,  87  ;  oxalate  of,  figure  of  crystals, 

85  ;  quantity  eliminated  of,  84. 
Uric  acid,  97,  98,  99,  100,  101, 102  ;  derivatives  of, 

56  ;    occurrence  of,   100  ;    origin  of,  102,  103  ; 

salts  of,  101  ;  substances  related  to,  103  ;  tests 

for,  101,  102. 
Urine,  pigments  of,  56,  134. 
Urobilin,  134, 
Urochrome,  136. 
Urohsematin,  136. 
Uromelanin,  136. 
Urohasmatoporphyrin,  136. 


Valektls,  on  lime  salts  in  tissues,  41. 

\ks  Beseben,  on  fecundation,  228-230. 

Van  Helmont,  on  fermentation,  176. 

Van  Mansveldt,  on  elasticity  of  muscle,  399. 

Vapours,  effect  of,  on  protoplasm,  291,  292. 

Variability,  definition  of,  31. 

Vater,  corpuscles  of,  336. 

VA0QUELIN,  on  spermatin,  78. 

Vln'es,  physiology  of  plants,   23 ;    on   molecular 

force,  14  ;  on  polar  bodies,  226. 
Vital  action,  16. 
Vitality,  definition  of,  33. 

Vital  properties  of  connective  tissues,  346,  347. 
VitelUn,  73,  74. 
Vitelline  membrane,  246. 
VoiT,  on  creatinin,  95  ;  on  origin  of  urea,  87. 
VoLEMANN,  on  elasticity  of  muscle,  399. 
VoLTA,  discoveries  of  437,-438,  439. 
Voltaic  element,  364,  369-373  ;  pUe,  discovery  of, 

439. 
Volume,  measurement  of,  7. 
Volumetric  estimation  of  glucose,  155,  156. 
Von  Helmboltz,  see  Helmholtz. 
Von  Wittich,  on  cell  movement,  296. 

W 
Wagner,  on  colloid  matter,  77. 
Waller,  on  muscular  fatigue,  430. 


51 G 


INDEX. 


Waltek,  on  origin  of  nrc:i,  ST. 

Water,  influence  of,  in  fermentation,  193 ;  i>hysio- 

logical  action  of,  3() ;  proportion  of,  in  the  body, 

tissues,  etc.,  35,  36. 
Watts,  on  polarized  light,  (i'.i. 
Wax  embedding  of  tissues,  27'.'. 
Weber,  paradox  of,  399  ;  on  cohesion  of  muscle, 

397  ;  on  elasticity  of  muscle,  39S,  390. 
Weight,  measurement  of,  .5. 
Weismank,  on  heredity,  239,  240,  241. 
Wertheim,  on  elasticity  of  tissues,  345. 
White  fibro-cartilage,  330 ;  how  to  examine,  497. 
WiLLi.\iis,  microtome  of,  281. 
Witthaus,    on  acid  urate  of  lithium,    101;    on 

cholesterin,  147  ;    on  glycerine,  148  ;   on  oleic 

acid,  HiS  ;  on  sarcin,  103  ;  on  taurocholic  acid, 

107. 
WoliLEK,  on  oxalic  acid,  lii7. 
Work,  definition  of,  10 ;  done  by  muscle,  424-427  ; 

done  by  muscle,  measurement  of,  425,  426 ;  done 

in    production   of  heat  in   muscle,   422,   423 ; 

measurement  of,  10. 


WouM-MuLLER,  analysis  of  nuclein  by,  78. 
WuNDERLiCH,  On  production  of  heat  in  muscle,  424. 
WuNDT,  on  elasticity  of  muscle,  399. 

X 

Xanthin,  103,  104. 
Xanthophane,  spectrum  of,  140. 
Xantho-proteic  reaction,  64,  72. 

y 

Yeiist,  analy^^is  of,  177. 

Yellow  fibro-cartilage,  how  to  examine,  497. 
Yeo,  G.  F.,  on  latent  period  of  muscle,  503. 
Young,  on  the  modulus  of  elasticity,  345. 
YirsG,  on  temperature  in  fermentation,  192. 


Zaleski,  on  creatiniu,  95 
Zoogloea,  190. 


END. 


GLASGOW  :    PRINTED  BV  ROBERT  MACLEHOSE,  UNIVERSITY  PRESS. 


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